312 PHYLUM XIV. ANTHOPHYTA 



Flowering Plants the small flowers are clustered into 

 many-flowered heads, from which fact these plants and 

 their relatives are known as "Composites." The face 

 or top of the head is flat, and its back is covered with 

 many spreading, green bracts, constituting the "invo- 

 lucre." The face of the head bears the many small 

 crowded flowers each in the axil of a stiff bract. Those 

 on the margin ("ray flowers") are 

 quite sterile, and have large flat 

 corollas (of five petals united below 

 into a tube, but "ligulate" above), 

 while the remainder ("disk flowers") 

 produce seeds and have tubular 

 FIG. i93.-Heiianthus. coro n as> Examining one of the 

 latter we find that the bicarpellary pistil is wholly 

 covered by the thin cup: the calyx ("pappus") is re- 

 duced to two or a few scales: the corolla consists of five 

 petals united into a tube which is five-pointed at its 

 summit: the five stamens are borne on the inside of the 

 corolla tube, and the anthers are united by their mar- 

 gins into a tube which surrounds the style. The pistil 

 has a long style which divides above into two recurved 

 style branches, each stigmatic on its upper surface. 

 There is but one erect ovule at the base of the single 

 cavity of the ovary. On ripening the cup and ovary wall 

 become tough and leathery, and closely surround the 

 relatively large seed, and this structure is known as an 

 "achene." 



576. The Dandelion flower head (Taraxacum, or Leon- 

 todon) is in plan much like that of the Sunflower, but here 

 the flowers all have flat (ligulate) corollas, and all produce 

 seeds. Each flower consists of a bicarpellary ovary which 

 is wholly covered by the thin cup, on whose upper margin 

 is the whorl of many fine bristles (the calyx, or pappus), 



