Survey of Plant Kingdom 131 



produced. Asexual reproduction may occur by fragmentation of the 

 plant or by special bodies known as gemmae (jem'i) (L. gemma, bud), 

 depending upon the species. 



(1) Class Hepaticae (Liverworts). — Many of the liverworts grow 

 fiat on the substratum and have dorsoventral bodies, with the dorsal 

 (upper) surface of their gametophyte different from the ventral (lower) 

 surface. Certain liverworts have flat, lobed, thallose bodies which have 

 a fancied resemblance to the lobes of a liver of higher animals; for 

 example, Marchantia (Fig. 43). Other species, called the leafy liver- 

 worts, have bodies with "leaf like" structures (not true leaves), thus 



/^rchegoniophc re 



0\jam 



ArcheaorYiuvn ^..^rgg^^^ 



~Kh\7p\ds 



gemma 



J. 



Ar)thend\ophorQ ^ ^ ^p^ 

 (Aiale) 



Fig. 43. — Common liverwort {Marchantia sp.) of the phylum Bryophyta, class 

 Hepaticae. A, Female plant or thallus; B, gemma produced in a cupule; the 

 gemma will develop into a thallus similar to the one on which it was formed; C, 

 longitudinal section of an archegonial receptacle (female) ; D, archegonial recep- 

 tacle in a longitudinal section much enlarged; E, male plant or thallus; F, longi- 

 tudinal section of an antheridial receptacle (male) ; G, antheridial receptacle in 

 logitudinal section much enlarged ; H, archegonial receptacle in longitudinal sec- 

 tion still further enlarged and with a sporophyte (spore-forming plant) attached 

 to the base of the archegonium; the sporangium is filled with spores; I, spore 

 germinating into a new thallus with its rhizoids. The thalli will develop into adult 

 liverwort plants. 



resembling certain true mosses, except that these leafy liverworts are 

 prostrate on the substratum; for example, Porella (Fig. 44). There are 

 approximately 8,500 species. Liverworts are considered in greater detail 

 in a later chapter. 



Examples: Thalloid liverworts (Marchantia) (Fig. 43) and leafy 

 liverworts (^Por^//<2J (Fig. 44). 



