292 BOTANY OF CROP PLANTS 



base of the fruit. There are eight stamens with glabrous 

 fihform filaments and oblong anthers. Three of the stamens 

 closely surround the styles and dehisce outward, while the 

 five others are inserted outside of these three, and dehisce 

 inward. The single ovary is one-celled and one-ovuled and 

 bears three style branches, which are bent back in fruit. 



The plant begins to bloom when quite young and continues 

 until frost. 



Dimorphism and Pollination.^ Common buckwheat has 

 dimorphous flowers, i.e., there are two forms. One of these 

 forms has short styles and long stamens, and the other, long 

 styles and short stamens. This condition is known as hetero- 

 styly. The pollen grains of short-styled flowers are larger 

 than those of long-styled flowers. Usually, all the flowers on 

 one plant are of one form or the oti er. Occasionally, how- 

 ever, both long-styled and short-styled plants may bear a 

 very few flowers with styles and stamens of the same length. 

 These "equal-styled" flowers are not fertile. The seeds 

 from either form of flower will produce buckwheat plants, 

 some of which produce one form and some the other. 



Buckwheat is regularly visited by numerous insects. 

 Heterostyly is a condition which tends to prevent self-polli- 

 nation. 



Fruit. — The mature fruit (Fig. 115, A) is a triangular (some- 

 times two- or four-angled) crustaceous achene, brown, 

 streaked with black, or entirely black; the point of the 

 "grain" is the stigmatic end, while the opposite end shows 

 a fragment of the flower stalk (pedicel), and small, persistent, 

 withered calyx lobes which have become adherent to the peri- 

 carp. The " hull " is the pericarp and attached portions. 



Seed. — The single seed conforms in shape to the pericarp. 

 There is an abundance of white, dry, floury endosperm in 

 which is imbedded the embryo. Buckwheat endosperm is 



