VEGETATIVE REPRODUCTION. 



211 



III. Brood buds, etc. 



297. Simple forms.— In their simplest form brood buds 

 consist of a single cell, though more commonly they are two- 

 to several-celled. Like spores, they are supplied with re- 

 serve food. The shape of brood buds is various. When not 

 furnished with distinct organs, they are club-shaped, lentic- 

 ular, or spherical. In some thalloid liverworts (^Marchantia 

 and Lunularia) they are produced on the surface of the thal- 

 lus, surrounded wholly or on one side by an outgrowth from 

 the surface forming a cup or a crescentic ledge (figs. 39, 

 177). In some mosses broody 

 buds arise from the apex of the 

 Stem, either in cup-like clusters 

 of leaves or exposed (A, A', fig. 

 178) ; in others they are smaller 



Fig. 177. Fig. 178. 



Fig. T77.— Thallus of Marchantia, seen from above, showing the cups containing brood 

 buds. Natural size —After Kerner. 



Fig. 178. — Brood buds of mosses. A, upper part of the stem of Azt/acut/tm'um ««- 

 drogynum, with a cluster of brood buds at apex (magnified about 8 diam.), one of 

 which is enlarged 120 diam. in A' . B, tip of leaf of Syrrhofiodon sender (magnified 

 about 10 diam.) showing brood buds ; B' some more enlarged (about 40 diam.).— After 

 Kemer. 



and simpler and are developed upon the leaves {B, B' , fig. 



178). In all the mossworts they belong to the gametophyte. 



298. Shoots. — In fernworts and seed plants the brood 



buds are especially abundant, and often reach considerable 



