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 ]

☞ 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 algæ. 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 Hyphæ, 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 ]

a. Belonging to, or covered with, lichens. Tennyson. [ 1913 Webster ]

a. Of, pertaining to, or obtained from, lichens. [ 1913 Webster ]

Lichenic acid. (a) An organic acid, C14H24O3, obtained from Iceland moss. (b) An old name of fumaric acid. [ 1913 Webster ]

a. Having the form of a lichen. [ 1913 Webster ]

n. (Chem.) A substance isomeric with starch, extracted from several species of moss and lichen, esp. from Iceland moss. [ 1913 Webster ]

{ } a. [ Cf. F. lichénographique. ] Of or pertaining to lichenography. [ 1913 Webster ]

n. One who describes lichens; one versed in lichenography. [ 1913 Webster ]

n. [ Lichen + -graphy: cf. F. lichénographie. ] A description of lichens; the science which illustrates the natural history of lichens. [ 1913 Webster ]

n. One versed in lichenology. [ 1913 Webster ]

n. [ Lichen + -logy. ] The science which treats of lichens. [ 1913 Webster ]