462 



BOTANY 



types (e.g. the corymbs of Achillaea formed by an aggregation of 

 capitula). 



An inflorescence is also usually provided with more or less 



V 



Fig. 396.— Diagrams of cymose inflorescences. A, Dichasium ; B, bostryx, or helicoid cyme ; 

 G, cincinnus, or scorpioid cyme. 



reduced bracteal leaves or hypsophylls ; those from the axil of which 

 a flower or flowering shoot springs are called subtending LEAVES or 

 bracts, while the leaves borne on the stalks of the flowers are desig- 

 nated BRACTEOLES Or PROPHYLLA. 



Sub-Class I 

 Monoeotyledones 



Flowers constructed for the most part after the trimerous, penta- 



cyclic type ; seeds usually abund- 

 antly provided with nutritive 

 tissue ; embryo with one coty- 

 ledon. Herbs and woody plants 

 with closed and usually scattered 

 vascular bundles (Fig. 397), nearly 

 always without cambium ; when 

 a cambium is present, it lies out- 

 side the vascular bundles. Leaves 

 commonly with parallel nerva- 

 tion. 



The embryo, in the majority of 

 Monocotyledons, is small in com- 

 parison with the albumen (endo- 

 sperm, rarely perisperm). It con- 

 sists, as a rule, of a short hypo- 

 cotyl, with a still shorter root and 

 a relatively large cotyledon, which 



on germination remains wholly or in part enclosed within the seed, 



and exhausts the albumen of its food material. 



Fig. 397.— Transverse section of the stem of 

 Zm Mais, cv, Vascular bundle. (For further 

 description see p. 109 and Fig. 124.) 



