CUCURBITA 585 



flower reaches anthesis, however, the difference in the relative 

 development of the ovules is somewhat equalized so that the 

 chances for fertilization are about the same for all. The ovules 

 appear first as small papillae on the margins of the placentae and 

 become strictly anatropous at maturity. 



The growth of the upper portions of the carpels results in the 

 formation of three undiverged styles, and the three stigmas are 

 distinct, appearing as bilobed or divided structures. The tissue 

 of the ring-like nectary is derived from the receptacle at the base 

 of the perianth tube, after the carpellary lobes have grown upward 

 to form the styles and stigmas. (Fig. 305, A.^ 



The Staminate Flower. — The number of staminate flowers 

 produced always exceeds that of the pistillate ones. They have a 

 campanulate corolla, which with the calyx forms an undiverged 

 basal perianth tube. The lobes of the latter are linear and alternate 

 with the five deeply lobed segments of the corolla. (Fig. 304, C) 

 The three stamens are not alike, as two of them are tetraspo- 

 rangiate, producing two locules at maturity, while the third 

 is bisporangiate and unilocular. The filaments are free, but 

 the stamens are more or less united by their anthers, which 

 grow vigorously in length, forming long vermiform coils. (Fig. 

 306.) 



The sequence of development of the floral parts, according to 

 Heimlich (16), is perianth tube, stamens, pistillodium, calyx 

 lobes, and corolla lobes. As in the carpellate flower, the floral 

 axis is at first club-shaped, but its apex soon broadens and the 

 ring-like fold of the perianth tube is formed. This is followed 

 by the differentiation of the primordia of the stamens, which 

 arise in a close spiral arrangement, the first one to develop being a 

 unilocular stamen which is sometimes referred to as the "half 

 stamen." The second stamen develops in a position opposite the 

 leaf in the axil of which the flower arises, and the third is formed 

 at a point that is equidistant from the other two. The three 

 primordia of the pistillodium then develop in a close spiral, their 

 lobes alternating with the stamens. 



Each stamen develops a wide filament with a broad connective 

 which supports the anther. The filaments are diverged from the 

 receptacle at the base of the inner surface of the perianth tube; 

 and, within the staminal cycle, a slightly-lobed, ring-like nectary 

 is developed which encircles the pistillodium. The rudimentary 



