lis 



PLANT STUDIES 



Fig. 130. A fniit of witch 

 hazel discliai-giiig its 

 seeds.— After Beal. 



light or sandy soil (see Fig. 120). 

 When the work of the season is over, 

 and the absorbing rootlets have 

 shriveled, the plant is easily blown 

 from its anchorage by a gust of wind, 

 and is trundled along tlie surface like 

 a liglit wicker ball, the ripe seed ves- 

 sels dropping their seeds l)y tlie way. 

 In case of an obstruction, such as a 

 fence, great masses of these tumble- 

 weeds may often be seen lodged 

 against tlie windward side. 



79. Discharge of spores. — In many 

 plants the distribution of spores and 

 seeds is not provided for Ijy any of 



the metliods just mentioned, but the vessels containing 



them are so constructed that they are discliarged with 



more or less violence and are some- 



wliat scattered. 



Many spore cases, especially those 



of the lower plants, burst irregularly, 



and witli suthcient violence to throw 



out spores. In the liverworts pecu- 

 liar cells, called elaters or "jumpers," 



are formed among the spores, and 



when tlie w;dl cf the spore case is 



ruptui'ed the elaters are liberated, 



and by their iictive motion assist in 



discharging the spores. 



In most of the true mosses the 



sjiore case opens by pushing off a 



lid at the apex, which exposes a 



delicate fringe of teeth covering the 



mouth of the urn-like case. These 



teeth bend in and out of the open 



spore case as they become moist or 



Fig. 1^3. A pnd of wild bean 

 bursting, the two valves 

 violently twisting and dis- 

 charging the seeds. — After 

 Beal. 



