CUCURBITACE.E 339 



and NOTONIA, or imbricated in several rows, the outer 

 shorter than the inner as in the Sunflower. They 

 may be green like leaves, or scarious and coloured 

 as in *ANAPHALIS and * GNAPHALIUM the Cud- weed, 

 or have scarious brown tips, and in some, e.g. the 

 Thistle, they are spiny. All these characters are used 

 to distinguish the genera from each other and to class 

 them into separate tribes, and should therefore be 

 noticed when examining a plant. 



The family COMPOSITE is the largest order of 

 flowering plants and members of it are found in all 

 parts of the world. It is also in many respects the 

 most perfect and most fully developed of all, for the 

 arrangement of the flowers in heads often with brightly 

 coloured rays of ligulate florets, and the mechanism 

 by which the pollen is offered to passing insects, are 

 very simple but very effective aids to cross fertiliza- 

 tion (see p. 235), while the pappus or the hooked 

 bristles which so many achenes of the COMPOSITE 

 have, are undoubtedly the cause of rapidity with which 

 some species spread. 



Most are herbs, but there are some trees and shrubs, 

 and on our hills are some species of SENECIO which 

 straggle over other shrubs. 



CUCURBITACE^E 



Examples :- 



CUCUMIS MELO, L. The Melon. 



A coarsely hairy herb, with ribbed hollow stems 

 climbing (if it is allowed to climb) by tendrils. 



Leaves alternate, exstipulate, petioled, orbicular or 

 reniform, five-lobed. 



