LIFE HISTORY OF A LIVERWORT 



217 



to tide over periods of drought. Tubers in liverworts were 

 first discovered and recognized in a species of Anthoceros. 

 At least two species {Fossomhronia tuherifera and An- 

 thoceros tuberosus) received their specific names from their 



Fig. 162. — Anthoceros phymatodes. Portion of thallus showing develop- 

 ing tubers. X about 15. (After M. A. Howe.) 



characteristic of forming tubers. In some species the 

 tubers appear as swellings or outgrowths on the under- 

 side of the thallus; in others (Figs. 162 and 163) as en- 

 largements of the tips of thallus-lobes. The leafy liver- 

 wort, Bryopteris filicina (Fig. 164), illustrates vegetative 

 multiplication by stolons. 



Fig. 163. — Anthoceros phymatodes. Mature tuber, sprouting. X about 

 21. (After M. A. Howe.) 



198. The Sporophyte. — After fertilization the oosperm 

 develops a young embryo, and from the lower or basal 

 half the foot develops, with projections reaching down 

 into the tissue of the gametophyte (Fig. 165). After the 



