- rock moss
- Lichen Li"chen (l[imac]"k[e^]n; 277), n. [L., fr. Gr.
leichh`n.]
1. (Bot.) One of a class of cellular, flowerless plants,
(technically called {Lichenes}), having no distinction of
leaf and stem, usually of scaly, expanded, frond-like
forms, but sometimes erect or pendulous and variously
branched. They derive their nourishment from the air, and
generate by means of spores. The species are very widely
distributed, and form irregular spots or patches, usually
of a greenish or yellowish color, upon rocks, trees, and
various bodies, to which they adhere with great tenacity.
They are often improperly called {rock moss} or {tree
moss}.
[1913 Webster]
Note: A favorite modern theory of lichens (called after its inventor the Schwendener hypothesis), is that they are not autonomous plants, but that they consist of ascigerous fungi, parasitic on alg[ae]. Each lichen is composed of white filaments and green, or greenish, rounded cells, and it is argued that the two are of different nature, the one living at the expense of the other. See {Hyph[ae]}, and {Gonidia}. [1913 Webster]
2. (Med.) A name given to several varieties of skin disease, esp. to one characterized by the eruption of small, conical or flat, reddish pimples, which, if unchecked, tend to spread and produce great and even fatal exhaustion. [1913 Webster]
The Collaborative International Dictionary of English. 2000.
