HO IV TO KNOW THE WILD FLOWERS 



These heads vary greatly in size and appearance. At times 

 they are large and solitary, as in the dandelion. Again they are 

 small and clustered, as in the yarrow. 



In some genera they are composed of flowers which are all 

 similar in form and color, as in the dandelion, where all the 

 corollas are strap-shaped and yellow ; or, as in the common 

 thistle, where they are all tubular-shaped and pinkish-purple. 



In others they are made up of both kinds of flowers, as in 

 the daisy, where only the yellow central or disk-flowers are 

 tubular-shaped, while the white outer or ray-flowers are strap- 

 shaped. The flower-heads of the well-known asters and golden 

 rods are composed of both ray and disk-flowers also; but while 

 the ray-flowers of the aster, like those of the daisy, wear a dif- 

 ferent color from the yellow disk-flowers, both kinds are yellow 

 in the golden rod. 



If the dandelion or the chicory (PL CXLV. ) is studied as an 

 example of a head which is composed entirely of strap-shaped 

 blossoms; the common thistle or the stick-tight (PI. LXXX.) 

 as an example of one which is made up of tubular-shaped blos- 

 soms ; and the daisy or the sun-flower (PL LXXIX.) as an example 

 of one which combines ray and disk-flowers — as the strap-shaped 

 and tubular blossoms are called when both are present — there 

 need be little difficulty in the after recognition of a member of 

 this family. The identification of a particular species or even 

 genus will be a less simple matter ; the former being a task which 

 has been known to tax the patience of even advanced botanists. 



Mr. Grant Allen believes that the Composites largely owe 

 their universal sway to their *' co-operative system." He says ; 

 *^ If we look close into the Daisy we see that its centre com- 

 prise^ a whole mass of little yellow bells, each of which consists 

 of corolla, stamens, and pistil. The insect which alights on the 

 head can take his fill in a leisurely way, without moving from 

 his standing-place ; and meanwhile he is proving a good ally of 

 the plant by fertilizing one after another of its numerous ovaries. 

 Each tiny bell by itself would prove too inconspicuous to attract 

 much attention from the passing bee ; but union is strength for 



xxxiv 



