Orchidaceae Cypripedium parviflorum var. exiliens Sheviak

Cypripedium parviflorum var. exiliens Sheviak
Orchidaceae
Synonyms: Cypripedium parviflorum var. makasin auct. non (Farwell) Sheviak
Global Distribution:
Alaska and northwestern Canada south through the
Canadian Rocky Mountains; disjunct in South Dakota.87
Alaska Distribution:
Arctic Tundra, Intermontane Boreal.
Ecoregions Occupied: Brooks Range, Yukon-Old Crow Basin, North Ogilvie
Mountains.
Conservation Status:
S2S3 G5TNR.
Description87
Petals pale, dull, green-tan,
(23) 27 to 45 (52) mm long
Lips golden yellow, (16)
20 to 24 (26) mm long
Bracts 2 (rarely more), tubular,
sheathing, occasionally sparsely
pubescent at least on the lower half
4 cm
Leaves arched and spreading
from the lower stem
Leaves 3 to 5, lanceolateelliptic, ascending
Illustration by Matthew L. Carlson
87
Cypripedium parviflorum var. exiliens
General:
Perennial herb from slender rhizomes and coarse, fibrous
roots; plants small, slender.
Leaves:
Lanceolate-elliptic, ribbed, ascending, arched and spreading
from the lower stem with sheathing base.
Flowers:
Bracts 2 (rarely more), sheathing, tubular; uppermost bract
glabrous to sparsely pubescent if not leaf-like, pubescent in
the lower-half if leaf-like; flowers 1 (rarely 2), intensely
sweet-scented when young, becoming rose-scented at
maturity; lip (16) 20 to 24 (26) mm long, golden yellow;
sepals and petals pale, dull, green-tan, finely marked with
clusters of red-brown spots; petals (23) 27 to 45 (52) mm
long.
Fruits:
Capsules erect, ellipsoid, ribbed.
© Bruce Bennett 2011
Ecology
Elevation:
Known from 260 to 920 m in Alaska.
Landform:
Slopes, rock outcrops, river bluffs.
Soil Type:
Scree, rock, rocky soil, loam; often associated with
calcareous substrates but also documented from one
location on acidic substrate; seeds of Cypripedium
88
Cypripedium parviflorum var. exiliens
species lack carbohydrate reserves and require
mycorrhizae to successfully germinate and produce
above-ground growth.88
Moisture regime:
Usually dry, occasionally moist.
Slope:
Flat to steeply sloped.
Aspect:
Not limited to any aspects, but often appearing on
southern aspects.
Vegetation type:
Open spruce forest, aspen woodland.
Associated species:
Arctous alpina, Dryas octopetala,
Rhododendron tomentosum ssp. decumbens.
Longevity:
Cypripedium species are long-lived perennials that
develop very slowly and may require several years to
develop above-ground growth.88
Phenology:
Flowering early June, possibly sooner, through mid-July;
fruiting mid-July through August.
Population estimate:
Nine known occurrences in Alaska; a population in an
open spruce forest on calcareous substrate consisted of
100 individuals.
Reproductive biology: Cypripedium parviflorum var. exiliens may be of hybrid
origin;87 C. parviflorum and C. montanum can hybridize
to form C. × columbianum where the ranges of the two
species overlap when growing in mixed or adjacent
stands;87 Cypripedium species are pollinated by bees.88
Herbivory:
Cypripedium species are grazed by deer in parts of North
America88 and may be grazed by other herbivores in
Alaska.
Similar Species87
Cypripedium parviflorum var. exiliens is the only variety of C. parviflorum in
northern Alaska and northwestern Canada. C. parviflorum var. pubescens (S1)
occurs in Southeast Alaska. Previously, material from northern Alaska and
northwestern Canada has often been referred to C. parviflorum var. makasin.89
The morphology of these three varieties is compared in the table below; however,
their ranges do not overlap in Alaska.
Species
Bracts
Lip
Cypripedium
parviflorum var.
exiliens
Glabrous to sparsely
pubescent or pubescent
in the lower half when
young
Generally
smaller: (16) 20
to 24 (26) mm
long
Densely and
conspicuously silverypubescent when young
Sparsely and
inconspicuously
pubescent to glabrous
when young
Generally larger:
up to 54 mm
long
Cypripedium
parviflorum var.
pubescens
Cypripedium
parviflorum var.
makasin
Generally larger:
(18) 22 to 28
(31) mm long
Petals
Generally smaller:
(23) 27 to 45
(53) mm long,
green-tan with redbrown spots
Generally larger,
green-tan with redbrown spots
Generally larger:
(30) 35 to 55
(62) mm, entirely
dark brown
89
Cypripedium parviflorum var. exiliens
4 cm
ALA 137865
ALA 92413
© Bruce Bennett 2011
90