5o6 BOTANY OF CROP PLANTS 



Flowers. — The flowers are either single or in clusters, and 

 are terminal or axillary. Some are subtended by an involu- 

 cel which resembles the epicalyx of strawberries. This 

 involucre (Fig. 211) consists of three or more bractlets, which 

 may be separate or united. In the marsh mallow (Althaa), 

 the involucre consists of six to nine bractlets united at the 



Fig. 212. — Upland cotton (Gossypium hirsutum). Median lengthwise 

 section of flower. x 2. 



base; in AbuHlon, there is none; in Hibiscus, it is of numerous 

 narrow bractlets; and in cotton (Gossypium), there are three 

 large heart-shaped bractlets (Fig. 211). The flowers are 

 regular (Fig. 212), perfect, often large, rarely dioecious or 

 polygamous. There are five sepals (rarely three or four), 



