VEGETATIVE REPRODUCTION. 26l 



from spores until the mossworts are reached, in which the 

 alternation of phase is well marked. In their simplest form 

 such buds consist of a single cell, though more commonly 

 they are two- to several-celled. Some or all of their cells are 

 in the embryonic stage (^] 256). Like spores, they are sup- 

 plied with reserve food. 



362. Simple forms. — The form of brood buds is various. 

 When not differentiated into distinct organs, they are club- 

 shaped, lenticular, or spherical. In some thalloid liverworts 

 (Marchantia and Lunularid) they are produced on the surface 

 of the thallus, surrounded wholly or on one side by an out- 

 growth from the surface forming a cup or a crescentic ledge 

 (figs. 59, 290, 291). In some mosses brood buds arise from 



Fig. 290. — Thallus of Marchantia, seen from above, showing the cups containing brood 

 buds. See fig. 291. Natural size. — Alter Kerner. 



the apex of the stem, either in cup-like clusters of leaves or 

 exposed (A,A f , fig. 292); in others they are smaller and 

 simpler and are developed upon the leaves (B, B\ fig. 292). 

 In all the mossworts they belong to the gametophyte. 



363. Shoots. — In femwortS and seed plants the brood buds 

 belong to the sporophyte. In the latter they are espe< iallj 

 abundant, and often reach considerable size ami complexity 

 before being separated from the parent, usually consisting of 

 a short axis with a growing point and at least rudimentary 



