Lichen - Denver Botanic Gardens

FRED FUNGUS AND ALICE ALGAE’S
MARRIAGE IS (only) ON THE ROCKS
Like if you agree
Dave Falconieri, Deborah Darnell
and Beth Scott
June 1, 2016
Non-Vascular Plants & Fungi
Plants that have no specialized internal tissue for the conveyance of materials from
one part of the plant to another.
Algae
A large group of pigmented plants that use photosynthesis to produce carbohydrates
for nutrition. Can vary from single celled to many meters long (such as giant kelp).
Fungi
A large group of organisms that must absorb nutrients from the environment just like
animals. The parent plants are typically very inconspicuous, consisting of either a loose
web or a compact mass of fine threads (hyphae) called the mycelium. The conspicuous
part of the plant (e.g. toadstools) are the reproductive portions of the plant.
Algae + Fungi = Lichens
A symbiotic relationship between a fungus and an alga where one plant provides
structure and nutrients from the environment and the other provides carbohydrates
from photosynthesis.
Lichen Structure
Growth and Reproduction
• Growth is very slow
• Asexual reproduction
• Sexual reproduction
Growth Forms on Rocks
• CRUSTOSE – is closely
attached to the substrate;
lacks free lobes and a lower
cortex. 75% of lichens are
crustose.
• Example: Map Lichen
(Rhizocarpon geographicum)
• FOLIOSE or Leaf Lichen– has
thin, leaf-like lobes, is loosely
attached to the substrate; has
both upper and lower cortex.
• Example: Colorado Rockfrog
(Xanthoparmelia colorensis)
Growth Forms not on Rocks
• FRUTICOSE or Shrub Lichen –
has an erect, simple or
branched, cylindrical thallus
attached at a single point. On
trees & bark.
• Example: Old Man’s Beard
(Usnea hirta)
• SQUAMULOSE – has scalelike lobes, usually closely
attached, but free or
upturned at the edge.
On soil.
• Example:
(Psora tuckermanii)
Fact or Myth?
The orange color of lichens on Mt. Goliath
comes from pika urination
• No reference to color changes of
lichens in literature other than dry vs.
wet
• Pigment comes from an algae high in
Carotenoids
• Usnic Acid – in lichens with a nasty
taste – protection from sun, grazing
animals
• Sunburst lichens: common in areas
high in nitrogen, consistent with
small mammal/bird droppings
Xanthoria elegans
Elegant Sunburst
Uses of Lichens
17,000 Lichens found in all climate zones
• Not a major food source for
animals
• Pharmacological
• Usnic acid unique to
lichens – diet aid, antimicrobial
• Dyes and Pigments
• Litmus
• Hummingbird nests with
spider webs
References
• Baron, George, Understanding Lichens, 1999.
• Bland, John, Forests of Lilliput, 1971.
• Corbridge, James N. and William Weber, A Rocky
Mountain Lichen Primer, 1998.
• Scagel, et al, An Evolutionary Survey of the Plant Kingdom,
1965.
• St. Clair, Larry L., A Color Guidebook to Common Rocky
Mountain Lichens, 1999.