Documenting Local Biodiversity: Ptilidium pulcherrimum, the most beautiful liverwort

Ptilidium pulcherrimum with sporophytes.
Ptilidium pulcherrimum with sporophytes.

Winters are long where I live so I spend a lot of my indoor time reading about plants, fungi, lichens, and small wildlife like spiders and crustaceans. Eventually spring arrives and I get to test my new knowledge.

Last spring, on trees and fallen logs along the edge of the tamarack swamp, I found some interesting non-vascular plants. These are liverworts or hepatophytes, moss-like plants but not closely related to mosses. One liverwort that caught my attention is Ptilidium pulcherrimum, one of the leafy liverworts in the order Jungermanniales. Leafy liverworts have three sets of leaves (other liverworts are merely flattened stems). The first two sets are arranged laterally in one plane along the stem, the third set is on the ventral side of the stem. Upon first inspection this plants leafy-ness is not obvious as everything about the plant is small. When I first found it the Ptilidium was in its sporophyte phase and looked like a mass of small black-capped mushrooms popping up through stubby mosses. After viewing it through the camera lens I realized it was not a fungus but a liverwort.

Ptilidium pulcherrimum with sporophytes.
Ptilidium pulcherrimum with sporophytes.

Description
P. pulcherrimum forms a thin tufted mats of pinnately branching stems covered in small, deeply divided overlapping leaves (1.8 to 2.4 mm wide). Plant color is usually green or sometimes tawny brown when exposed to bright sunlight. The roundish, black spore cases are held on thin almost translucent green stalks. These later split open along four seams and the spreading sections look a bit like flower petals.

Habitat and Plant Communities
P. pulcherrimum is common in the coniferous forest region of Minnesota and can be found on a variety of substrates including moist basaltic rocks, on the bases of trees in conifer swamps, and on moist decaying logs and stumps usually with other high humidity preferring liverworts, mosses, and lichens.

Miscellaneous
The species epithet “pulcherrimum” for this tiny plant is from a Latin word meaning “most beautiful”. This seems a more appropriate name than the so-called common name “naugahyde liverwort”. The word “liverwort” is in reference to the resemblance of some species to liver lobes hence the name which means “liver herb or plant”. The word “hepatophyte” also means “liver plant”. In Britain, P. pulcherrimim is known as the “tree fringewort”.

Next post: Conocephalum, the great snakeskin liverwort.

References
BBS Field Guide online pages

Long, D., 2010. Ptilidium pulcherrimum, Tree Fringewort in Mosses and Liverworts of Britain and Ireland – a field guide. Atherton, I., Bosanquet, S., and Lawley, M., editors. 2010. British Bryological Society 2010. Latimer Trend and Co. Ltd, Plymouth, England.

Schuster, Rudolf M. 1953. Boreal Hepaticae, A Manual of Liverworts of Minnesota and Adjacent Regions. The American Midland Naturalist (Vol. 49, No. 2, March 1953).

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