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 
ae corollas (of five petals united below 
GF into a tube, but “ligulate’” above), 
while the remainder (“disk flowers’’) 
produce seeds and have tubular 
corollas. 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. Onripening 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), 
Vv 
i 
Fic. 193.—Helianthus. 
