54 



BOTANY OF CROP PLANTS 



metrical halves by any diameter (Figs. 156 and 162). Such a 

 flower is said to be radially symmetrical, or acfinomorphic, 

 or regular. Contrast this symmetry with that in such flowers 

 as the pea or bean (Fig. 1 72^), in which there is but one plane 

 through which the flower can be divided to separate it into 

 two symmetrical halves. Such a flower is said to be bi- 

 laterally symmetrical, or zygomorphic, or irregular. 



Relative Positions of Flower Parts. — In the gooseberry or 

 currant flower (Fig. 129), for example, the ovary is below 

 the stamens, corolla, and calyx, and is said to be inferior. . A 

 flower with an inferior ovary is said to be epigynous (above the 

 gynoecium or carpels) . When the calyx, corolla, and stamens 

 are inserted on the receptacle below the ovary, the ovary is 

 superior, and the flower hypogynous (below the gyncecium). 

 The flowers of mustards are hypogynous. There is a third 

 intermediate type of flower, well illustrated by the cherry 

 (Figs. 157 and 163), apple (Fig. 157), etc., in which the 

 petals and stamens are inserted on a calyx rim and arise at 

 about the level of the ovary. In such a case the ovary is 

 half-inferior or half -superior , and the flower perigynous 

 (around the gynoecium). 



Union of Flower Parts.- — In the primitive flower type, such 

 as the buttercup, the sepals, petals, stamens and carpels are 

 all separate and distinct. A more or less complete union of 

 the parts of each set of floral leaves may take place. For 

 example, in gooseberries and currants, the sepals are united 

 to form a calyx tube, in the potato flower the petals are united 

 to form a corolla tube, in the cotton flower the stamen fila- 

 ments are joined, and in many instances — onion, apple, 

 orange, and others — the carpels are united. The adjectives 

 to describe these various cases are as follows: 



