n 



AGGREGATE FLOWERS. 87 



genus Kuhriia. The florets in compound flowers, with an 

 exception or two, have each five stamens. They are also 

 monopetalous, and superior, each one standing on a single 

 naked seed. 



The central portion of a compound flower is called its 

 disk, while the portion which surrounds this, is called its 

 radius or ray. In the Daisy, the disk is yellow, the ray be- 

 ing white. It is a curious fact, that though these parts are 

 often differently colored, still there are only certain colors 

 under which they ever appear. Thus the disk is most fre- 

 quently yellow, while the rays may be yellow also, or white, 

 red, or blue. But no instance has ever been known in which 

 the flower had yellow rays, with a white, red, or blue disk. 



AGGREGATE FLOWERS. 



Flowers are called aggregate, when several florets are sit 

 uated on the same receptacle, each floret having its anthers 

 distinct and separate, and not united into a cylinder, as in the 

 compound florets. Dr. Smith observes that flowers of this 

 kind are seldom yellow, but are most commonly either blue, 

 purple or white. The Teasel (Dipsacus,) and the Cat's eye, 

 (Scabiosa,) are examples. 



We have now described and illustrated all parts of a Plant, 

 from the Root to the Seed, and have defined such botanical 

 terms as are most necessary for the young botanists to un- 

 derstand, and be able to apply, when he goes into the field, to 

 collect and distinguish flowers. 



We have not in the usual manner, given a list of terms be- 

 longing to each subject, before such terms had been illustra- 

 ted and explained, because the student can gain a propel 

 knowledge of scientific words, only by understanding how 

 they are applied. It is therefore worse than useless for him 

 to burthen his memory with a list of terms in advance, since 

 he would thus be in danger of confounding them. But as 

 terms of science belonging to the same subject, often have 

 a mutual relation to each other, the pupil, after having learned 

 their uses individually, will be enabled much better to under- 

 stand and remember the application of each, by having them 

 thrown together. 



What is the central portion of a compound flower called 1 What ia 

 said of the colors of the disk and ray ? What are aggregate flowers 1 



