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Having the surface rough and crumbling; as, many lichens are tartareous.

f the vegetable kingdom, which includes those flowerless plants, such as fungi, algæ, and lichens, that consist of a thallus only, composed of cellular tissue, or of a congeries of cells, or even of separate cells, and never show a distinction into root, stem, and leaf.

A phylum of plants of very diverse habit and structure, including the algæ, fungi, and lichens. The simpler forms, as many blue-green algæ, yeasts, etc., are unicellular and reproduce vegetatively or by means of asexual spores; in the higher forms the plant body is a thallus, which may be filamentous or may consist of…

. -- Tree louse (Zoöl.), any aphid; a plant louse. -- Tree moss. (Bot.) (a) Any moss or lichen growing on trees. (b) Any species of moss in the form of a miniature tree. -- Tree mouse (Zoöl.), any one of several species of African mice of the subfamily Dendromyinæ. They have long claws and habitually live in trees.…

A pendulous branching lichen (Usnea barbata); -- so called from its resemblance to hair.

An apothecium in certain lichens, having a spherical surface marked with spiral or concentric ridges and furrows.

A genus of lichens, most of the species of which have long, gray, pendulous, and finely branched fronds. Usnea barbata is the common bearded lichen which grows on branches of trees in northern forests.

ating, a complex acid obtained, as a yellow crystalline substance, from certain genera of lichens (Usnea, Parmelia, etc.).

upon air and water, and Fungi, which contain no chlorophyll, and live on organic matter. (Lichens are now believed to be fungi parasitic on included algæ.}

Pertaining to, derived from, or designating, an acid obtained from a lichen (Cetraria vulpina) as a yellow or red crystalline substance which on decomposition yields pulvinic acid.