210 



PRACTICAL COURSE IN BOTANY 



230. Intermediate types. Flowers like the peach and 

 rose represent an intermediate type in which the calyx, 

 petals, and stamens are attached to a prolongation of the 

 receptacle that extends above the ovary, but is not united 

 with it (Fig. 301). In general, a flower is not considered as 

 belonging to the epigynous kind unless the ovary is more or 

 less consolidated with the parts around it (Fig. 304). 



III. STUDY OF A COMPOSITE FLOWER 



MATERIAL. The largest heads attainable should be selected, as the 

 florets are small at best, and difficult to handle. The large cultivated sun- 

 flower (Helianthus annuus) makes an ideal specimen, if accessible. Oxeye 

 daisy and dandelion can be obtained throughout the season almost every- 

 where, but the former has no pappus, and the latter does not show the 

 tubular disk flowers. Other common specimens are : for spring, mayweed, 

 Jerusalem artichoke, coreopsis, arnica; for late summer and autumn, 

 China aster, golden aster (Chrysopsis) , sneezeweed, elecampane and, 

 in fact, the great majority of flowers to be found at this season are of the 

 composite family. Oxeye daisy is used as a model in the text on account 

 of its general accessibility, but almost any specimen of the radiate kind 

 will meet all essential conditions of the analysis. 



231. The ray flowers. Examine the upper side of an ox- 

 eye daisy through a lens. Of what is the yellow button in the 

 center composed? Count the narrow, petal-like rays dis- 

 posed around 

 the center. To 

 decide what they 

 are, look for a 

 small two-cleft 

 body at the base 

 of the ray ; this 

 is the pistil. 

 Do you see any 

 stamens in the 



307 305 



FIGS. 303-308. An oxeye daisy : 305, a flower head; 

 306, vertical section of a head ; 307, disk flower ; 308, ray 

 flower, enlarged. 



ray ? An exam- 

 i nation will show 

 that all the rays 



