. A textbook of botany for colleges and universities ... Botany. BRYOPHYTES lOI. (2) JUNGERMANWIALES General character. â â This is by far the largest group of liverworts, its members living in all conditions of moisture from very wet to very dry. They are especially abundant in tropical forests, being very common on the bark of trees {epiphytic) and on leaves (epiphyllous), while some grow on the ground. Two great groups are recognized : (i) thallose forms, whose gametophyte body is a thallus resem- bling that of the Marchantiales in general outline (see fig. 777); (2) foliose forms, with lea
. A textbook of botany for colleges and universities ... Botany. BRYOPHYTES lOI. (2) JUNGERMANWIALES General character. â â This is by far the largest group of liverworts, its members living in all conditions of moisture from very wet to very dry. They are especially abundant in tropical forests, being very common on the bark of trees {epiphytic) and on leaves (epiphyllous), while some grow on the ground. Two great groups are recognized : (i) thallose forms, whose gametophyte body is a thallus resem- bling that of the Marchantiales in general outline (see fig. 777); (2) foliose forms, with leafy bodies (fig. 235). However, there is Fig. ^ . 1 ,. bearing a sporophyte with complete gradation from thallus bodies, iââg ^^^^^ (indicating also through those whose thallus is more and position of archegonium); more deeply lobed, to those in which the *^ ''l^* <^°'= °° *,<= °'^" , ,. portion of the thallus in- lobes have become distmct leaves. dicate antheridia. The most essential distinction between the two groups is based upon the position of the archegonia, which of course involves the position of the sporophytes. In the thallose forms the archegonia are on the dorsal surface of the thallus (figs. 231, 232); and on this account they are called the Anacrogynae, mean- ing archegonia not at the apex. In most foliose forms the apical cell becomes an archegonium initial; and on this account they are called Acrogynae, meaning archegonia at the apex (fig. 235). The acrogynous Jungerman- niales are known commonly as the leafy liverworts, or some- times as scale mosses. In contrast with the Marchantiales, the Jungermanniales show very little differentiation of the tissues of the gametophyte; but they show very great differentiation in the form of the gametophyte. (a) Anacrogynae Gametophyte.âThe gametophyte of the simplest Anacrogynae, such as Aneiira and PeJUa, are the simplest gametophytes known among. Please note that these images
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