Orchid seed diversity - Nees Institut for biodiversity of plants

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Orchid seed diversity
Orchid seed diversity
A scanning electron microscopy survey
A scanning electron microscopy survey
Wilhelm Barthlott
Bernadette Große-Veldmann
Nadja Korotkova
The orchid family (Orchidaceae), with some 22 000 species, is
one of the two largest families of plants. In spite of the vast available literature on orchids, rather little is known about their seeds,
which are generally considered as wind dispersed, small and reduced “dust seeds”.
For this first monograph of orchid seeds, the authors have analysed some 1400 collections of orchid seeds over the last four decades by scanning electron microscopy (SEM) and other methods.
The material studied represents about 1100 species from 350 genera (out of about 880 recognized orchid genera).
This monograph provides a unique and indispensable resource
for all those studying orchid systematics, those seeking to identify
orchid seeds, as well as those with more general interests in the
Orchidaceae.
What is included?
Wilhelm Barthlott
Bernadette Große-Veldmann
Nadja Korotkova
Epidendroideae – Cymbidieae
135
A
B
C
D
E
F
G
H
• 620 scanning electron micrographs of orchid seeds
• detailed seed descriptions for 350 genera, as well as for 14
tribes and the five orchid subfamilies
• an introduction summarizing earlier studies on orchid seeds
and current knowledge of orchid phylogeny
• a consistent terminology for characters of the orchid seed
coat
• the definition of 17 orchid seed types
• a discussion on the systematic and diagnostic value and evolution of orchid seed characters
Fig. 55. Epidendroideae – Cymbidieae – Cymbidiinae, Cyrtopodiinae – A, B: Dipodium paludosum, length:
800 µm – C, D: Graphorkis lurida, length: 300 µm – E, F: Porphyroglottis maxwelliae, length: 500 µm – G, H:
Cyrtopodium parviflorum, length: 700 µm.
• seed characters and seed types visualized on 26 phylogenetic trees
Shape of testa cells
• references
• an appendix listing the sources of the orchid seed material
studied
• an index to genera and higher taxa
elongated, rectangular
elongated, rounded at the end
Gomesa
Leochilus
Notylia
Ornithocephalus
Pachyphyllum
Warrea
Zygopetalum
Houlletia
Maxillaria
Dressleria
Catasetum
Galeandra
Graphorkis
Dipodium
Cymbidium
Calypso
Corallorhiza
Govenia
Meiracyllium
Encyclia
Epidendreae
Chysis
Coelia
Bletia
Earina
Agrostophyllinae
Dendrobium
Cadetia
Epigeneium
Bulbophyllum
Malaxis
Liparis
Bromheadia
Vanda
Aerides
Phalaenopsis
Angraecum
Dendrobiinae
Malaxideae
Cymbidieae
Vandeae
Campylocentrum
Polystachya
Neobenthamia
Sirhookera
Eria
Mediocalcar
Collabium
Plocoglottis
Spathoglottis
Calanthe
Agrostophyllinae
Podochileae
Collabieae
Phaius
Arundina
Dendrochilum
Thunia
Glomera
Coelogyne
Bletilla
Tropidia
Corymborkis
For information on ordering, please visit: www.bgbm.org/englera
Calypsoeae
Epidendrum
Cattleya
Arpophyllum
Isochilus
Ponera
Barthlott W., Große-Veldmann B. & Korotkova N. 2014: Orchid
seed diversity: A scanning electron microscopy survey. – Berlin:
Botanic Garden and Botanical Museum Berlin-Dahlem. – Englera
32. – ISBN 978-3-921800-92-8. – Softcover, 17.6 × 25 cm (B5),
245 pages, 620 micrographs, 26 phylogenetic trees and 7 other
figures. – Price: EUR 25.
Cymbidieae
Anguloa
Cyrtopodium
Elleanthus
Sobralia
Palmorchis
Neottia
Limodorum
Aphyllorchis
Epipactis
Gastrodia
Monophyllorchis
Wullschlaegelia
Xerorchis
Nervilia
Arethuseae
Tropidieae
Sobralieae
Neottieae
Gastrodieae
Triphoreae
Calypsoeae
Xerorchideae
Nervilieae
Epidendroideae
Orchid seed diversity
A scanning electron microscopy survey
Wilhelm Barthlott1
Bernadette Große-Veldmann1
Nadja Korotkova1,2
1 Nees-Institut für Biodiversität der Pflanzen, Rheinische Friedrich-Wilhelms-Universität Bonn
2 Institut für Biologie/Botanik, Systematische Botanik und Pflanzengeographie,
Freie Universität Berlin und Botanischer Garten und Botanisches Museum Berlin-Dahlem
Published by the
Botanic Garden and Botanical Museum Berlin-Dahlem
as
Englera 32
Serial publication of the Botanic Garden and Botanical Museum Berlin-Dahlem
December 2014
Englera is a monographic series, published at irregular intervals by the Botanic Garden and Botanical
Museum Berlin-Dahlem (BGBM), Freie Universität Berlin. In scope it is an international series, publishing peer-reviewed original material from the entire fields of plant, algal and fungal taxonomy and
systematics, also covering related fields such as floristics, plant geography and history of botany, provided
that it is monographic in approach and of considerable volume.
Editor: Nicholas J. Turland
Production Editor: Michael Rodewald
Printing and bookbinding: LASERLINE Digitales Druckzentrum Bucec & Co. Berlin KG
Englera homepage: http://www.bgbm.org/englera
Submission of manuscripts: Authors should contact by e-mail Nicholas J. Turland, Editor of
Englera, Botanischer Garten und Botanisches Museum Berlin-Dahlem, Freie Universität Berlin,
Königin-Luise-Str. 6 – 8, 14195 Berlin, Germany; e-mail: [email protected]
Subscription and exchange: BGBM Press, Att. of Susanne Schmutzler, Botanischer Garten
und Botanisches Museum Berlin-Dahlem, Freie Universität Berlin, Köni­­gin-Luise-Str. 6 – 8, 14195
Berlin, Germany; e-mail: [email protected]
© Botanischer Garten und Botanisches Museum Berlin-Dahlem, 2014
All rights (including translations into other languages) reserved. No part of this issue may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publishers.
ISSN 0170-4818
ISBN 978-3-921800-92-8
Addresses of the authors:
Prof. Dr. Wilhelm Barthlott, Nees-Institut für Biodiversität der Pflanzen, Rheinische Friedrich-Wilhelms-Universität Bonn, Venusbergweg 22, 53115 Bonn, Germany; e-mail: [email protected]
Bernadette Große-Veldmann, Nees-Institut für Biodiversität der Pflanzen, Rheinische FriedrichWilhelms-Universität Bonn, Meckenheimer Allee 170, 53115 Bonn, Germany; e-mail: [email protected]
Dr. Nadja Korotkova, Institut für Biologie/Botanik, Systematische Botanik und Pflanzengeographie,
Freie Universität Berlin & Botanischer Garten und Botanisches Museum Berlin-Dahlem, Köni­­ginLuise-Str. 6 – 8, 14195 Berlin, Germany; e-mail: [email protected]
Cover design: From Beer J. G. 1863: Beiträge zur Morphologie und Biologie der Familie der
Orchideen (Tab. III & IV). – Wien: Druck und Verlag von Carl Gerold’s Sohn.
Contents
5
Contents
Summary and key words . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Preface and acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Introduction
Current knowledge of orchid phylogeny . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Seeds of orchids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Earlier seed morphology studies in Orchidaceae . . . . . . . . . . . . . . . . . . . . . . . .
Aims of this study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12
13
14
18
Descriptors and terminology
Seed characters
Seed shape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Seed size (length of seed) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Seed colour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Number of testa cells (along longitudinal axis of seed) . . . . . . . . . . . . . . . . . . . .
Shape of individual testa cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Testa cell pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Anticlinal wall curvature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transverse anticlinal walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Intercellular gaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Surface structure of periclinal walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cuticular layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Modifications of testa cell corners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Seed types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19
20
20
20
20
20
21
21
22
23
23
23
24
Material and methods
Seed material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Taxonomic coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scanning electron microscopy (SEM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Orchidaceae systematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Character coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tracing of characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
27
27
27
27
27
28
Seed descriptions
Apostasioideae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vanilloideae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pogonieae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vanilleae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cypripedioideae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Orchidoideae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chloraeeae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Codonorchideae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cranichideae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cranichidinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Galeottiellinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29
29
29
30
32
32
33
33
33
34
34
6
Contents
Goodyerinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Manniellinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pterostylidinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Spiranthinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diseae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brownleeinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coryciinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Huttonaeinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Satyriinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diurideae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Acianthinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Caladeniinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cryptostylidinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diuridinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drakaeinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Megastylidinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Prasophyllinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rhizanthellinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thelymitrinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Orchideae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Epidendroideae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Arethuseae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Arethusinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coelogyninae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Calypsoeae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Collabieae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cymbidieae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Catasetinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coeliopsidinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cymbidiinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cyrtopodiinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Eriopsidinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Eulophiinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maxillariinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oncidiinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stanhopeinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vargasiellinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Zygopetalinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Epidendreae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bletiinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chysinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coeliinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Laeliinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pleurothallidinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ponerinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gastrodieae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Malaxideae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Neottieae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Nervilieae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
34
36
36
36
38
38
39
39
40
40
40
40
41
41
41
42
42
43
43
43
43
48
49
49
49
51
52
53
53
54
54
55
55
55
56
57
62
63
63
65
66
66
66
66
70
71
72
72
73
74
Contents
7
Epipogiinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Nerviliinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Podochileae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Eriinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thelasinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sobralieae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Triphoreae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diceratostelinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Triphorinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tropidieae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Xerorchideae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vandeae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Aeridinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Aerangidinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Angraecinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Polystachyinae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Epidendroideae unplaced genera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
74
74
75
75
76
76
77
77
77
77
77
77
78
80
81
82
82
Discussion
The systematic and diagnostic value and evolution of orchid seed characters . . . . . . . . . .
Are orchid seeds systematically relevant? – Earlier evidence from comparative studies . . . .
Are orchid seeds systematically relevant? – Earlier evidence from cladistic studies . . . . . .
Summary of the character reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Concluding remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
87
91
92
93
94
SEM micrographs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Selected seed characters visualized on phylogenetic trees
Seed shape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Seed size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Seed colour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Number of testa cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Shape of testa cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Testa cell pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Anticlinal wall curvature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transverse anticlinal walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Intercellular gaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ridges on periclinal walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Verrucosities on periclinal walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Perforations on periclinal walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cuticular layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wax caps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Testa cell extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Seed types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
186
188
190
192
194
196
198
199
200
202
204
206
207
209
210
211
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
Appendix: Sources of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
8
Summary
Summary
The Orchidaceae with some 22 000 species is
one of the two largest plant families. Despite
of the vast literature on orchids, rather little is
known about their seeds, which are generally
considered as wind dispersed, small and reduced
“dust seeds”.
Based on some 1400 collections of orchid
seeds analysed by SEM and other methods over
the last four decades, about 7000 micrographs
of some 1100 species from 352 (out of c. 880)
genera were evaluated for this first monograph
on orchid seeds.
Orchid seeds exhibit an astonishing diversity.
This is not only reflected in their sizes (between
0.1 mm in Oberonia and 6 mm in Epidendrum)
and shapes, but especially in the complexity of
their lightweight seed-coat architecture and hierarchical surface sculpturing. A consistent terminology for characters of the orchid seed coat
is proposed.
Taxa at subtribal to tribal levels are often well
characterized by seed-coat characters. Fifteen
selected characters were mapped on well-sup-
ported molecular phylogenetic trees and were
found to be largely consistent with the major
clades. Combinations of characters classified
into 17 seed types often delimit tribes (e.g. Cym­
bidieae, Epidendreae, Vandeae). Highly specialized features like polyembryony (up to 12 embryos per seed in Thecostele) or highly adaptive
(with respect to dispersal biology) seed-coat
features (e.g. in Galeola, or the sophisticated
seed-attachment mechanism of Chiloschista) are
restricted to only a few genera.
This monograph provides a first atlas (624 micrographs) and data to identify the major groups
of orchid seeds and a terminology for taxonomic
purposes. The first character reconstruction of
seed characters based on modern molecular phylogenetic hypotheses allows an application for
further systematic studies of the family.
Key words – Orchidaceae, orchids, seeds, testa,
surface, micromorphology, SEM, taxonomy,
phylogeny, dispersal biology
Preface and acknowledgements
9
Preface and acknowledgements
Orchids, one of the two largest families of flowering plants, have fascinated botanists and plant
enthusiasts over centuries. The literature fills
shelves in libraries and is almost unmanageable.
There are countless pictures of the fascinating
splendour of orchid flowers. Only few people
have studied the morphology of the seeds of the
about 22 000 orchid species: the usual notion in
textbooks says orchid seeds are tiny, reduced and
uniform – not very inspiring for a botanist.
The monograph presented here has a very long
history – more than 40 years after our research began a comprehensive description of the surprising
diversity of orchid seed coats is finally presented.
Therefore, a brief review of this history as well as
the persons involved is worthy of mention.
In 1971 one of the first scanning electron microscopes (a Cambridge Stereoscan 500) was
established from DFG (Deutsche Forschungsgemeinschaft) funds at the Institute of Systematic
Botany and Plant Geography at the University
of Heidelberg. I myself was able to work with
the SEM for my dissertation on the taxonomy
of epiphytic Cactaceae that also relied on characters I could observe in the SEM. For us Heidelberg postdocs (Nesta Ehler, Rainer Schill
and myself), these were the pioneering days of
scanning electron microscopy. Already in 1977,
we could present a first monograph on the SEM
analysis of the surfaces of 2200 plant species,
also discussing functional aspects, the most important of which later became widely known as
the lotus effect.
Heidelberg was also an international centre of
orchid research in the seventies. The Institute of
Systematic Botany and Plant Geography and the
Botanical Garden were linked through Werner
Rauh who was the director of both these institutions. He built up an extraordinary collection of
plants on his many expeditions to tropical countries. Besides the succulent and bromeliad collection, the orchids alone occupied three large
greenhouses. This was perhaps the world’s biggest living collection of orchids at that time. This
collection was curated by Karlheinz Senghas, an
internationally renowned orchid taxonomist and
editor of the new edition of Rudolf Schlechter’s
“Die Orchideen”, the most comprehensive orchid monograph at that time.
I collected the first orchid seeds in the greenhouses in 1972 and was fascinated by the unexpected diversity that opened up under the
electron microscope. With the curator Karlheinz
Senghas and my two postdoctoral friends we
published the very first SEM study of orchid
seeds in 1974. Then I discovered the small monograph on orchid seeds by Joseph Georg Beer
(1863) in our library. Though hardly taken notice
of, it is a unique pioneering work in this field.
Josef Georg Beer (1803 – 1873) was a famous
Viennese fashion designer and worked until
1843 in his father’s company, and then devoted
himself to private extensive bromeliad and orchid collection. He was Secretary General of the
Austrian Imperial and Royal Horticultural Society and among other things organized the horticultural part of the world exhibition in Vienna in
1867 on behalf of the Austrian government. His
work on orchid seeds published in 1863 included remarkable astonishing coloured lithographic
plates, self-designed by Beer, giving an impression of the variety of shapes, colours, as well as
transparency and lightness of orchid seeds that
a SEM image cannot convey. One of his unsurpassed plates is reproduced here (Fig. 7); it and
one other from the same work have been used
for the cover design.
The investigations were intensified after 1974.
Karlheinz Senghas pollinated the orchids in the
living collection systematically for seed production and identified the material. The Swiss
pharmacist Othmar J. Wildhaber in Zurich had
collected seeds of almost all European orchids
over decades and introduced us to his material.
Gunnar Seidenfaden provided material from
Thailand. Friedhelm Butzin regularly sent samples from the rich stock of the Botanic Garden
and Botanical Museum Berlin-Dahlem, and Peter Taylor sent material from the herbarium of
the Royal Botanic Gardens, Kew. Berlin and
Kew have contributed a significant portion of the
material examined.
10
In Robert L. Dressler (Florida and Panama),
we found an enthusiastic scientist to support the
work in various ways, and he visited us several
times in Heidelberg. One had the impression that
everyone was happy that someone finally dealt
with the so long-neglected seeds of orchids. I
was invited to give a talk at the 8th World Orchid
Conference in Frankfurt in 1976.
The old Cambridge Stereoscan micrographs
from that time are still unsurpassed in quality:
the images of Calypso bulbosa or Satyrium odo­
rum and many others presented here date from
the year 1973. Structural analysis followed in
which we could clarify the nature of the stabilizers of the balloon-shaped seed coats as helical
wall thickening by using an oxygen ion etching
method. Shortly after, a publication on the functional morphology of dust-seeds followed.
Our collection of orchid seeds had now grown
to over 500 taxa, and the SEM micrographs – in
pre-digital times on photo paper – filled many
file folders. I was still a postdoc, with the aim to
qualify as professor. And I realized that I could
not handle the seed morphology of the huge
orchid family alone. And a lucky circumstance
helped: a study friend, Bernhard Ziegler, today
a retired biology teacher at the English Institute in Heidelberg, mentioned that he would
like to graduate in addition to his professional
activity. He started his dissertation in 1978 and
could complete it already in 1981 thanks to the
extensive preliminary work and already available data. A particularly spectacular finding we
soon published was the extendable helical wall
thickenings of Chiloschista (Fig. 5). A smaller
overview article followed and we had planned
the big orchid seed monograph for 1982. But
we never finished the manuscript – Bernhard’s
time was fully engaged by his profession as a
teacher, and I myself was appointed professor at
the Freie Universität Berlin in 1981.
The works were continued from 1985 at the
University of Bonn where I was now director
at the Botanical Institute and of the Botanical
Gardens and had ideal working conditions.
High-resolution electron microscopy was available on-site and we also carried out an energy
dispersive X-ray microanalysis (EDX) of seeds.
Through Karlheinz Senghas, I continuously re-
Preface and acknowledgements
ceived new material from the growing Heidelberg collection, and additionally from collectors
and herbaria around the world. In addition, the
general work on scanning electron microscopy
of cuticular plant surfaces was continued – today around 150 000 micrographs of surfaces of
about 20 000 species have accumulated in our
archives.
To illustrate this alone for the Orchidaceae:
this work is based on the analysis of about 1100
species from 350 genera. For this purpose, a total
of about 1400 collections was examined in the
SEM; on average five micrographs were taken
per collection. In particularly complex cases –
such as in Chiloschista lunifera – up to 100 pictures were taken per taxon. A total of about 7000
micrographs were evaluated for this monograph.
It was clear that a publication of such data
nowadays would require a phylogenetic context – that was also available because the orchids
are very well studied with molecular systematic approaches and their relationships are well
understood. The processing of the data started
from about 2009 by Nadja Korotkova, who was
familiar with the methods for character reconstruction in a phylogenetic context from her dissertation on the molecular systematics of Cac­
taceae – Rhipsalideae. Soon after, Nadja and I
found a highly motivated and dedicated student:
Bernadette Große-Veldmann. She became interested in the orchid seeds and we decided she
could continue the character reconstruction as
her B.Sc. thesis, which we supervised. Bernadette’s commitment for this project was incredible and the fast progress is undoubtedly owed
to her.
Finally, I would like to convey my appreciation
to all of the many people who have contributed
toward the success of this project. In addition to
all the colleagues mentioned before, I would like
to thank Friedrich G. Brieger (São Paulo), Guido
J. F. Pabst (Rio de Janeiro), Clarence K. Horich
(Costa Rica), Mark Clements (Australia) and
Friedhelm Butzin (curator of orchids in the Herbarium Berlin-Dahlem). But this list is far from
being complete – a glance at the list of the material sources makes clear how many herbaria and
collectors have contributed. Our sincere thanks
are given to them all. We want to thank all the
Preface and acknowledgements
many technical assistants and student assistants
who assisted in scanning electron microscopy
and image editing over the years.
Robert L. Dressler and Peter K. Endress reviewed an earlier draft of this monograph and
provided useful comments. Bernd Haeseling and
Alexandra Runge prepared the photographic images and plates with great technical skill. We finally acknowledge the financial support from the
Academy of Sciences and Literature in Mainz in
the framework of the long-term project “Biodiversity in Change”.
The basis of this monograph is the work
in Heidelberg. The commitment of Werner
Rauh (1913 – 2000) and Karlheinz Senghas
(1928 – 2004) has made this work possible. This
monograph is dedicated to them.
Bonn, June 2014
Wilhelm Barthlott
11
12
Introduction
Introduction
Current knowledge of orchid phylogeny
Orchidaceae is one of the two largest angiosperm
families. At present some 22 000 species and 880
genera are accepted. More than 23 000 species
and 1600 genera are known in the Asteraceae,
making it the largest flowering plant family.
Still, even larger species numbers have been estimated for both families (information taken from
the Angiosperm Phylogeny Website (Stevens
2001). Some authors regard Orchidaceae as being the largest plant family and it is undoubtedly
the largest family of monocotyledons.
The Orchidaceae were always regarded as a
natural group but were considered so unique that
they used to be treated as their own order, Or­
chidales, in former classification systems, e.g.
by Takhtajan (1997) Nowadays they are with
high confidence included into the monocot order
Asparagales (APG 2003, 2009). The taxonomic
rank of certain groups within Orchidaceae has
been discussed controversially in the past and
groups such as cypripedioids, apostasioids, and
Fig. 1. – A: Green ripe fruit of Cochleanthes aromat­
ica (Epidendroideae). The mature dust-seeds can be
seen as whitish powder along the slit-like openings. –
B: dry fruit of Oncidium sp. (Epidendroideae).
vanilloids have been regarded as separate families besides Orchidaceae s.str. (see Pridgeon
& al. 2003b for an overview of former classification systems). These problems and uncertainties in orchid classification result from the
Orchidaceae being an extremely diverse and
species-rich family. Genera and other taxonomic
units were often established mainly based on
floral characters, construction of the column and
pollinia morphology. These characters however
are prone to homoplasy and especially the similarities in flower morphology are often a result
of co-evolution with pollinators.
New insights into the evolution of flowering
plants have been gained in the last 20 years since
the application of DNA sequence data became
widely used in phylogenetic studies. Knowledge
of relationships within the Orchidaceae has been
much expanded by a large amount of molecular
data (e.g. Cameron & al. 1999; Freudenstein &
Rasmussen 1999; Cameron 2004; Freudenstein
& al. 2004; Cameron & Molina 2006). All these
studies have found five well-supported major
lineages within Orchidaceae and a new formal
classification based on these clades was proposed by Chase & al. (2003); see also Chase
(2005). To date, Orchidaceae are subdivided into
the five subfamilies Apostasioideae, Vanilloide­
ae, Cypripedioideae, Orchidoideae and Epiden­
droideae.
The positions and circumscriptions of many
tribes and subtribes have also been clarified by
molecular data. An overview of phylogenetic
studies within Orchidaceae is given by Cameron
(2007). In contrast to former classification systems, there is now a large amount of data that
provides a robust phylogenetic hypothesis making a consensus on the classification and phylogeny of Orchidaceae conceivable. This knowledge on Orchidaceae phylogeny can now serve
as a framework to study the evolution of morphological features or ecological adaptations.
Morphological characters that could back up the
findings of molecular studies are still desirable.
Introduction
In contrast to various aspects of flower morphology, micromorphological characters such as seed
coats or pollen are usually barely influenced by
environmental conditions.
Seeds of orchids
Orchids produce capsules (Fig. 1) and typically form minute wind-dispersed seeds of only
0.1 – 6 mm in size. They are characterized by a
thin balloon-like seed coat and (in the majority of cases) the absence of endosperm (Fig. 2).
The seed coat usually consists of uniform cells;
seed coats that consist of different cell types occur only in genera with very specialized seeds
(see below). The embryo is much reduced and
consists usually of only a few cells, though some
species may contain more than one embryo per
seed. Polyembryony with up to 12 embryos per
seed (!) occurs in the seeds of Thecostele (Fig.
3).
The structure of the orchid seed coat is rather
conservative and supposed to be little prone to
selective pressure since there is one predominant
seed dispersal mechanism in the whole family. Orchids typically have tiny wind-dispersed
seeds, often called “dust-seeds”. Most orchids
are wind-dispersed, but there are exceptions and
the dispersal mechanisms of orchids are more
diverse than assumed earlier. A link of morphology and dispersal properties was already suggested by Arditti & al. (1980), and Healey & al.
(1980) noted that “there is a functional correlation between orchid seed morphology, their wettability, and aerodynamics. These in turn affect
the dispersion of the seeds”.
A unique dispersal mechanism occurs in the
Vanilloideae–Vanilleae: wind-dispersal by large
sclerified winged seeds (Fig. 4). This type of
anemochory is very different from the wind-dispersal of the tiny “dust-seeds” of the rest of the
family. Cameron & Chase (1998) assume different dispersal mechanisms for the Vanilleae,
including water dispersal for Epistephium and
zoochory not in only Vanilla, but also Galeola.
In addition to wind-dispersal, water-dispersal
(hydrochory) could play a role in some species
(Dressler 1981), e.g. in Epipactis gigantea (Epi­
13
dendroideae–Neottieae), a species often found
growing next to streams. Hydrochory as the main
dispersal mechanism has also been suggested
for some species of Disa (Orchidoideae–Dis­
eae). The seeds of some Disa are very different
compared to its related genera. They are unusually large and also contain endosperm, which
is unusual in orchids. This strikingly different
morphology has also been noted by Kurzweil
(1993). To explain this, Kurzweil discussed the
habitats and dispersal modes of Disa uniflora,
which occurs along the edges of perennial Western Cape streams where seeds must germinate
quickly to prevent them being washed away by
rain. Kurzweil therefore assumed that the Disa
seed is adapted for that habitat: the endosperm
allows a quick growth of the seedling.
Some genera have large fruits with aromatic
pulp and sclerified black seeds, both suggesting
adaptations to zoochory. This is found mainly in
the Vanilloideae (e.g. Vanilla, Erythrorchis and
Pseudovanilla). Sclerified seeds are also found
in Apostasia Blume and Neuwiedia Blume
(Apostasioideae), in Seleni­pedium (Cypripe­
Fig. 2. Orchid seeds usually have no endosperm; the
seed coat embraces like a balloon the air-filled space
between embryo and testa (Limodorum abortivum). –
A: fluorescence microscopic image of L. abortivum
– B: SEM image of L. abortivum: due to the high accelerating voltage of 30 keV (method after Wolter &
Barthlott 1991) the embryo becomes clearly visible.
14
Fig. 3. Thecostele alata is a unique case of obligate
polyembryony with three to twelve (!) embryos per
seed, which may be a record in plants. Only very rarely do seeds with one embryo develop.
dioideae), Rhizanthella (Orchidoideae) and Pal­
morchis (Epidendroideae). As far as is known,
sclerified seeds are not homologous in all these
genera (Freudenstein & Rasmussen 1999). All
these genera also produce fleshy fruits, which
do not open. In combination with this fruit type,
the sclerified seeds are most likely a convergent
adaptation to zoochory to protect the embryo in
the digestive tract.
Many orchids are epiphytes and therefore adaptations of seeds to epiphytism have been suggested. In Japanese Liparis (Epidendroideae),
the seed volumes and air spaces were found to
be significantly different between epiphytes and
terrestrial species (Tsutsumi & al. 2007). Differences were found in embryo volumes, seed volumes, and air spaces, as well as in the lengths
and widths of the embryos. Tsutsumi & al.
(2007) therefore concluded that embryo size is
correlated with the evolution of epiphytism and
that larger embryos may be an advantage for the
epiphytic life form, though they did not exactly
clarify which kind of advantage this would be.
A very elaborate seed attachment mechanism
is known from a tropical Asian epiphytic orchid
Chiloschista lunifera. This species has specialized seed-coat cells with helical wall thickenings, which extend upon contact with water and
produce long threads (Fig. 5). This mechanism
enables the seed to attach itself to moist tree bark
(Barthlott & Ziegler 1980). Some Epidendroide­
ae form testa extensions in the form of capitate
Introduction
ends or elaborate hooks (Fig. 6). These extensions have so far been found only in those On­
cidiinae species that are twig epiphytes and they
suggest to serve for attachment to the tree bark
(Chase & Pippen 1988).
The seeds of Sobralia dichotoma are unique
within the Orchidaceae and are the only known
example of an orchid seed truly adapted for water uptake (Prutsch & al. 2000). The seed coat
of S. dichotoma consists of three different cell
types and Prutsch & al. suggested that this is an
adaptation to protect the embryo from desiccation. The water uptake is possible through the
development of tracheoidal idioblasts – special
cells with secondary wall thickenings that resemble the tracheids of the vascular tissue system but are not true vascular elements (Prutsch
& al. 2000).
Earlier seed morphology studies in
Orchida­ceae
Orchid seeds have been known to science since
the middle of the 16th century from the works
and drawings of Conrad Gessner in his Historia
plantarum. But almost all publication focused
on the intriguing, complicated and aesthetically
fascinating flowers and their functions. Charles
Darwin spent years researching these flowers –
but in his admirable orchid book (Darwin 1862)
he mentioned the tiny seeds only marginally in
the last chapter. The earliest truly comprehensive publication on orchid seeds was the work
of Beer (1863), including beautiful and accurate
colour paintings, reproduced here (Fig. 7). Other
studies did not follow until more than a century
later, Arditti & Ghani (2000) reviewed the early
knowledge on orchid seed studies in detail. The
first study where the systematic value of orchid
seed characters was pointed out was presented
by Clifford & Smith (1969). Their study was
based on comparisons of 49 species mainly from
the tribes Epidendreae and Neottieae and found
“reasonable correlations” between suprageneric
groups and seed characters. Seeds of European
orchids were studied by Wildhaber (1970, 1972,
1974) based on light microscopy. Initial SEM
studies of orchid seeds showed that they were
much more diverse than previously assumed
Introduction
based on light microscopic surveys (Senghas
& al. 1974). This was followed by structural
analyses in which the fine balloon-shaped seed
coats could be clarified as helical wall thickening by oxygen ion etching. An overview of the
functional morphology of the dust-like seeds
appeared shortly after (Rauh & al. 1975). Barthlott (1976a) then undertook the first detailed
SEM study and pointed out the systematic and
taxonomic value of seed characters for orchid
systematics.
The only study covering the whole family is
an unpublished dissertation of B. Ziegler (1981),
which was supervised by W. Barthlott. Ziegler
had summarized characters to define 20 seed
types and discussed the correlation of single
seed characters as well as the seed types with
the Orchidaceae system of Dressler (1981). Ziegler found that seed characters were of high systematic and taxonomic significance and could
be used to support or define groups within the
family. Unfortunately, only some minor results
of this work were published (Barthlott & Ziegler 1980, 1981) but the results nevertheless became rather widely known (see below).
Many studies of orchid seed coat morphology
have been published representing selected taxonomic groups only or material from one geographic region. Arditti & al. (1979, 1980) and
Healey & al. (1980) presented morphometric
studies and SEM images of Cypripedium and
several Orchidoideae genera native to California and briefly discussed whether seed characters characterize genera. Chase & Pippen (1988)
analysed the seed morphology of the Oncidii­
nae and related subtribes and Chase & Pippen
(1990) analysed the seeds of Catasetinae. These
studies were even the first detailed examination
of orchid seed morphology at the subtribal and
generic level, besides the unpublished dissertation by Ziegler (1981). The conclusions of both
these studies were that seed characters are well
suited for defining generic relationships and circumscribing subtribes in Orchidaceae.
Wolter & Barthlott (1991) tried yet another
approach by using energy-dispersive X-ray
spectroscopy (EDX) to study orchid seeds.
They analysed seeds of 98 predominantly European terrestrial species with the aim of providing additional characters for comparative sys-
15
Fig. 4. Large winged seed (1300 µm) of Epistephium
parviflorum (Vanilloideae).
tematics. Wolter & Barthlott (1991) found that
the composition of elements in orchid seeds is
not influenced by soil and is therefore useful as
a character for comparative systematics.
Kurzweil & al. (1991) studied the phylogenetic relationships within the Pterygodium–Co­
rycium species group and made a first cladistic
analysis including seed characters. Here, they
found that the seed morphology was not informative but that only few groups showed synapomorphic seed characters. Kurzweil (1993) and
Linder & Kurzweil (1994) examined the seed
morphology of South African Orchidoideae,
mainly the tribes Orchideae and Diseae, and
discussed the taxonomic value of the seed characters in that group. Kurzweil (1993) concluded
that generally the characters he observed are not
useful as taxonomic characters, as they appear
to be not uniquely derived but to have evolved
independently in several genera. Nevertheless
he suggested that seed characters could support
relationships between some species.
Cameron & Chase (1998) studied seeds of vanilloid orchids (former tribe Vanilleae, currently
subfamily Vanilloideae). As stated by the authors, seed characters may be highly significant
for the systematics of this group as distinctive
seed types were observed in vanilloids: typical
orchid “dust-seeds”, sclerotic seeds in Vanilla,
and seeds with wing-like testa extensions in
Galeola, Erythrorchis and related genera.
Seed data play an important role in the most
influential Orchidaceae system, namely in the
works of Dressler (1993). Dressler had obtained
16
the actual seed data and SEMs he presented in
close collaboration with W. Barthlott and B.
Zieg­ler. Dressler adapted the concept of seedtypes as Ziegler (1981) had defined them; thus
this concept became widely known.
There are several seed studies using only material from one geographical origin or a country,
for example Spain (Ortúñez & al. 2006), Turkey
(Aybeke 2007; Akçin & al. 2009), the Western
Ghats, India (Krishna Swamy & al. 2004), the
Himalaya (Verma & al. 2012) or Japan (Tsutsumi & al. 2007).
Also statistical analyses of morphometric data
have been used for orchid seeds. Molvray &
Kores (1995) analysed seed characters of the
Diurideae and spiranthoid orchids. Their work
is mainly an attempt to re-define some of Ziegler’s seed types. Using a similar approach,
Chemisquy & al. (2009) analysed the seeds
of Chloraeeae using traditional and geometric
morphometrics with the aim of identifying diagnostic characters using a statistical approach
instead of a merely descriptive one. The overall
results, however, were largely inconclusive and
the authors could not find discrete characters to
support generic circumscriptions.
Introduction
Fig. 6. Corners of testa cells extended to hooks (Mi­
crocoelia obovata, Epidendroideae).
The authors of the most recent studies on orchid seeds aimed at finding seed characters to
support new generic circumscriptions based on
the results of molecular phylogenetic studies in
Orchideae (Gamarra & al. 2007, 2008, 2010,
2012). They found that seed ornamentation
patterns support the monophyly of Neotinea
(Gamarra & al. 2007), the splitting of Limnor­
chis from Platanthera (Gamarra & al. 2008),
and the expanded Anacamptis (Gamarra & al.
2012). Gamarra & al. (2010) summarized their
earlier findings in an additional overview article
Fig. 5. The unique seeds of Chiloschista lunifera (Epidendroideae). This species has extendable helical wall
thickenings that serve as an attachment mechanism. – A: drawing reproduced from Barthlott & Ziegler (1980) –
B: SEM-image; see also Fig. 88 G, H for further SEM images.
20
Descriptors and terminology
Seed size (length of seed)
Seeds of orchids range from 100 µm (Oberonia
similis) to 6000 µm (Epidendrum secundum).
The size used here refers to the length of the
seed and can be classified into five categories.
Medium-sized represents the average.
very small
100 – 200 µm
small
200 – 500 µm
medium-sized
500 – 900 µm
large
900 – 2000 µm
very large
2000 – 6000 µm
Seed colour
Fresh orchid seeds appear in many different colours. Most often it is whitish, brownish or dark
brown, but can also be beige, yellow, reddish,
orange, greenish, yellowish brown, or black
(Fig. 9). The colour is determined by the testa
and especially by the embryo, which can be an
intense yellow, orange or red-orange colour, or
greenish in seeds that contain chlorophyll.
Number of testa cells (along longitudinal axis
of seed)
The number of cells that form the testa in an individual seed coat varies highly between genera
but is almost constant within a genus. In some
genera, seeds are composed of only few (about
five) cells or fewer along the longitudinal axis of
the seed; in the most extreme case of only two
cells (Fig. 10 A). Since the number of testa cells
is coupled to cell division (Molvray & Chase
Fig. 9. Colour variation in orchid seeds – From top:
Vanilla, Angraecum, Calanthe, Dendrobium (twice),
Trichopilia. – Tube diameter: 6.5 mm.
Fig. 10. Variation in the number of cells per seed – A:
few cells in Cyrtorchis arcuata – B: many cells in So­
bralia dichotoma (Epidendroideae).
2003), this pattern probably results from a slow
or stopped cell division in the integuments after
fertilization. In other genera, where cell division
continues, the seed coats are composed of numerous small cells (Fig. 10 B).
Shape of individual testa cells
Most commonly the testa cells are tetragonal,
hexagonal or polygonal; sometimes the cell
shape is irregular. We distinguish three kinds of
testa cell shape: (1) all cells are more or less isodiametric (regardless of their actual shape); (2)
the cells are elongate in the longitudinal axis of
the seed (prosenchymatic) and rectangular; and
(3) the cells are elongate but rounded at the ends
(Fig. 11 A).
Only the testa cells located in the middle part
of the seed are used for description. This is because the shape of cells at the poles usually differs from those in the middle.
Testa cell pattern
Within a single seed coat, all cells are either
equal in size (regardless of their shape) or the
medial cells are highly elongate in comparison
to the cells at the poles (Fig. 11 B). Both these
patterns result from cell division in the outer integument.
Descriptors and terminology
Anticlinal wall curvature
The anticlinal cell walls are usually straight but
may also be curved or undulate. Undulations can
be S-like or V-like (Fig. 11 C). The thickness of
the anticlinal cell walls can vary; sometimes the
apices have thicker walls.
21
Transverse anticlinal walls
The transverse anticlines can also show modifications. Many Epidendroideae have elevated,
arch-like transverse anticlines (Fig. 11 D). Zieg­
ler (1981) suggested that seeds with such elevated anticlines fall more slowly thus can better
attach to the substrate.
Fig. 11. Overview of various seed characters – A: testa cells elongated and rounded at ends (Zygopetalum
mackayi, Epidendroideae) – B: seed with elongated medial cells (Anacamptis pyramidalis, Orchidoideae) – C:
undulated anticlinal walls (Disa uniflora, Orchidoideae) – D: transverse anticlinal walls elevated (Arundina
graminifolia, Epidendroideae) – E: intercellular gaps at cell corners (Vry­dagzynea sp., Orchidoideae) – F: intercellular gaps along anticlinal walls (Cyclopogon sp., Orchidoideae).
78
Aeridinae Pfitzer
Acampe Lindl.
Seed shape: scobiform, grain-shaped, A. mom­
bassensis slightly twisted; seed colour: yellowbrown; fewer than 5 testa cells along the longaxis; shape of testa cells: elongate, irregular,
rounded at the end; anticlinal walls: straight; cell
corners: often extended, with trichomes; periclinal walls: not visible.
Fig. 88 A, B.
Adenoncos Blume
Seed shape: scobiform, tapered apical end; seed
size: very small, length: 130 µm; seed colour:
yellowish; fewer than 5 testa cells along the
long-axis; shape of testa cells: strongly elongate
and irregular; anticlinal walls: straight; cell corners: smooth; periclinal walls: not visible, verrucosities; other features: seed surface is covered
with fine verrucose sculptures.
Fig. 88 C, D.
Aerides Lour.
Seed shape: scobiform; seed size: very small,
length: 250 µm; seed colour: brownish; fewer
than 5 testa cells along the long-axis; shape of
testa cells: elongate, irregular, rounded at the
end; all cells about the same size; anticlinal
walls: straight; transverse anticlinal walls: elevated, arch-like; cell corners: extended: small
trichomes on the basal and apical poles; periclinal walls: sometimes ridges of deeper testa cell
layers visible.
Fig. 88 E, F.
Arachnis Blume
No data and material available.
Chiloschista Lindl.
Seed shape: scobiform; seed size: small, length:
400 – 650 µm; seed colour: yellowish; fewer than
5 testa cells along the long-axis; shape of testa
cells: strongly elongate and irregular, rounded at
the end, secondary helical wall thickenings, well
visible at the basal part of the seed, barely visible at the apical part; anticlinal walls: straight,
marginal ridges with fine striated longitudinal
structures; cell corners: extended, micropapillae;
periclinal walls: not visible.
Epidendroideae – Vandeae
A very elaborate seed attachment mechanism is known from Chiloschista lunifera J.
J. Sm. This species has specialized seed-coat
cells with helical wall thickenings, which extend upon contact with water and produce long
threads. This mechanism enables the seed to
attach itself to moist tree bark (Barthlott &
Ziegler 1980).
Fig 5 A, B; 88 G, H.
Gastrochilus D. Don
Seed shape: longish scobiform; seed colour:
ochre; fewer than 5 testa cells along the longaxis; shape of testa cells: elongate, irregular,
rounded at the end; anticlinal walls: straight,
marginal ridges strong and twisted; cell corners:
smooth; periclinal walls: not visible, at the outer periclinal walls twisted marginal ridges of a
deeper testa cell layer are visible.
Fig. 89 E.
Holcoglossum Schltr.
Seed shape: scobiform, grain-shaped; seed
size: small, length: 300 µm; seed colour: strong
brown; fewer than 5 testa cells along the longaxis; shape of testa cells: elongate, irregular,
rounded at the end; anticlinal walls: straight;
transverse anticlinal walls: plain and dense marginal ridges; cell corners: smooth; periclinal
walls: not visible.
Fig. 89 A, B.
Kingidium P. F. Hunt
Seed shape: longish scobiform; seed size: small,
length: 400 µm; seed colour: light brown; fewer
than 5 testa cells along the long-axis; shape of
testa cells: elongate, irregular; transverse anticlinal walls: elevated, arch-like; cell corners:
extended, trichomes developed only apical and
basal; periclinal walls: not visible.
Fig. 89 C, D.
Luisia Gaudich.
No data and material available.
Papilionanthe Schltr.
Seed shape: scobiform; shape of testa cells:
elongate, irregular, rounded at the end; anticlinal
walls: straight; cell corners: smooth; periclinal
walls: verrucosities; other features: verrucose
98
Vanilloideae – Vanilleae
A
B
C
D
E
F
G
H
Fig. 18. Vanilloideae – Vanilleae – A, B: Galeola nudifolia, length: 1500 µm – C, D: Galeola septentrionalis,
length: 1500 µm – E, F: Lecanorchis multiflora, length: 2400 µm – G, H: Vanilla planifolia, length: 500 µm. – H:
longitudinal section through a mature seed showing the thick sclerified testa.
132
Epidendroideae – Cymbidieae
A
B
C
D
E
F
G
H
Fig. 52. Epidendroideae – Cymbidieae – Catasetinae – A, B: Galeandra devoniana, length: 500 µm – C, D: Gro­
bya amherstiae, length: 800 µm – E, F: Mormodes sp. (BG Heidelberg: 12314), length: 900 µm – G, H: Peristeria
guttata, length: 800 µm.
146
Epidendroideae – Cymbidieae
A
B
C
D
E
F
G
H
Fig. 66. Epidendroideae – Cymbidieae – Zygopetalinae – A, B: Aganisia pulchella, length: 400 µm – C, D: Ben­
zingia estradae, length: 250 µm – E, F: Cochleanthes aromatica, length: 250 µm – G, H: Cryptarrhena lunata,
length: 250 µm.
Phylogenetic trees: Shape of testa cells
Shape of testa cells
elongated, rectangular
elongated, rounded at the end
195
Gomesa
Leochilus
Notylia
Ornithocephalus
Pachyphyllum
Warrea
Zygopetalum
Houlletia
Maxillaria
Anguloa
Cymbidieae
Cyrtopodium
Dressleria
Catasetum
Galeandra
Graphorkis
Dipodium
Cymbidium
Calypso
Corallorhiza
Govenia
Calypsoeae
Epidendrum
Cattleya
Meiracyllium
Encyclia
Arpophyllum
Isochilus
Ponera
Chysis
Coelia
Bletia
Epidendreae
Earina
Agrostophyllinae
Dendrobium
Cadetia
Epigeneium
Dendrobiinae
Bulbophyllum
Malaxis
Liparis
Bromheadia
Vanda
Aerides
Phalaenopsis
Angraecum
Malaxideae
Cymbidieae
Vandeae
Campylocentrum
Polystachya
Neobenthamia
Sirhookera
Eria
Mediocalcar
Collabium
Plocoglottis
Spathoglottis
Calanthe
Agrostophyllinae
Podochileae
Collabieae
Phaius
Arundina
Dendrochilum
Thunia
Glomera
Coelogyne
Bletilla
Tropidia
Corymborkis
Elleanthus
Sobralia
Palmorchis
Neottia
Limodorum
Aphyllorchis
Epipactis
Gastrodia
Monophyllorchis
Wullschlaegelia
Xerorchis
Nervilia
Fig. 110 B. Character reconstruction for shape of testa cells: Epidendroideae.
Arethuseae
Tropidieae
Sobralieae
Neottieae
Gastrodieae
Triphoreae
Calypsoeae
Xerorchideae
Nervilieae
Epidendroideae
Phylogenetic trees: Seed types
Seed types
Bletia-type
Dendrobium-type
Eulophia-type
Epidendrum-type
Epidendrum-type: E. secundum variant
Pleurothallis-type
Gastrodia-type
Limodorum-type
Goodyera-type
Cymbidium-type
Maxillaria-type
Vanda-type: Maxillaria transition variant
Vanda-type: Gomesa variant
Vanda-type
Stanhopea-type
211
Gomesa
Leochilus
Notylia
Ornithocephalus
Pachyphyllum
Warrea
Zygopetalum
Houlletia
Maxillaria
Cymbidieae
Anguloa
Cyrtopodium
Dressleria
Catasetum
Galeandra
Graphorkis
Dipodium
Cymbidium
Calypso
Corallorhiza
Govenia
Epidendrum
Cattleya
Meiracyllium
Encyclia
Arpophyllum
Isochilus
Ponera
Chysis
Coelia
Bletia
Earina
Dendrobium
Cadetia
Epigeneium
Bulbophyllum
Malaxis
Liparis
Bromheadia
Vanda
Aerides
Phalaenopsis
Angraecum
Campylocentrum
Polystachya
Neobenthamia
Sirhookera
Eria
Mediocalcar
Collabium
Plocoglottis
Spathoglottis
Calanthe
Phaius
Arundina
Dendrochilum
Thunia
Glomera
Coelogyne
Bletilla
Tropidia
Corymborkis
Elleanthus
Sobralia
Palmorchis
Neottia
Limodorum
Aphyllorchis
Epipactis
Gastrodia
Monophyllorchis
Wullschlaegelia
Xerorchis
Nervilia
Calypsoeae
Epidendreae
Agrostophyllinae
Dendrobiinae
Malaxideae
Epidendroideae
Cymbidieae
Vandeae
Agrostophyllinae
Podochileae
Collabieae
Arethuseae
Tropidieae
Sobralieae
Neottieae
Gastrodieae
Triphoreae
Calypsoeae
Xerorchideae
Nervilieae
Fig. 121. A combination of several characters defines the 17 seed types named after representative genera.
Twelve of the seed types and their variants present in the Epidendroideae are plotted on the tree and indicate the
usefulness of the seed types to circumscribe clades.