VEGETATIVE TEPTOD UC'TWiY. 26 1 



from spores until the mossworts are readied, in wliicli llic 

 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 embr^•onic stage (^[ 256J. Like spores, they are sup- 

 plied with reser\'e food. 



362. Simple forms. — The form of brood buds is \arious. 

 "\^'hen not dilTerentiated into distinct organs, they are club- 

 shaped, lenticular, or spherical. In some thalloid li\er\vorts 

 {jMarchantia and Lunuldriii) 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 



P"iG. 290, — Thallus of INTarchantia, seen from above, showing the caps containing brood 

 buds. See tig. 291. Natural size. — After Kerner. 



the ape.\ of the stem, either in cup-like clusters of lea\es or 

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

 simpler and are de^"eloped upjon the leaves (j9, B' , fig. 292). 

 In all the mossworts they belong to the gametophvte. 



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

 belong to the spiorophyte. In the latter they are especially 

 abundant, and often reach considerable size and complexity 

 before being separated from the parent, nsualh- consisting of 

 a short axis with a growing point and at least rudimentary 



