Descriptive Catalog of the North American Hepaticae, North of Mexico.

The Hepaticae include quite diverse forms of vegetation, judging from the outward habit of the plants composing the group, yet all are more or less intimately related in their essential, that is. their reproductive characters. The lower forms consist of a mere expansion of tissue with no differentiation of stem and leaves. These thalloid forms are quite frequently confused with certain forms of lichens, but can be easily distinguished by the fact that while the lichen is usually rather dry and crustaceous or leathery, the hepatic is more loosely cellular or spongy in texture, and presents a moist or somewhat juicy appearance under pressure. Some of the aquatic forms have also been mistaken for algae. The higher forms of Hepaticae are more moss-like in general appearance, consisting of a stem and leaves usually closely creeping over some substance, which may be the ground itself, rotten wood, living trees, or rocks. These higher forms are sometimes confused with the true mosses (Musci), but can usually be distinguished by having the leaves two-ranked, while the mosses proper have them in several or many ranks. The more technical differences will be made apparent at a later paragraph.Ope