Because Fagopyrum cymosum is widely distributed, its pedicels are similar to Fagopyrum cymosum, such as joints, different styles, self-sterility, achenes, seedling cotyledons, etc. It is generally believed that Fagopyrum cymosum is the parent of Fagopyrum cymosum and Fagopyrum tataricum, but whether Fagopyrum cymosum is the ancestor of Fagopyrum cymosum remains to be studied. However, it is difficult to imagine that tartary buckwheat is the offspring of tartary buckwheat because of its equal style, self-pollination and dim achenes.

Scholars have different views on the evolution of buckwheat.

Campbell C.C. thinks that tartary buckwheat has a low degree of evolution, is self-compatible and develops towards self-compatibility; But buckwheat and buckwheat are self-incompatible systems. On the other hand, Daxi Jinjiang thinks buckwheat may belong to a genus with different styles, and the species of different styles may be the disappearance of different styles, and at the same time, it develops the mechanism of self-pollination, from cross-pollination to self-pollination.

Ye Gancan and others think that the evolution of buckwheat may be the result of natural selection. Its ancestors were completely different in two directions from the beginning, attracting insects, ensuring cross-pollination, promoting gene exchange and producing better offspring. Tartary buckwheat adapts to the direction of poor environmental conditions, with little or no insect activity, little change in flower structure, inconspicuous color, equal length of male and female stamens, and no different styles. In the harsh environment without insects, it can pollinate itself and let future generations continue.

Chen Qingfu (1999a, b) called Fagopyrum cymosum complex and divided Fagopyrum cymosum into Fagopyrum tataricum (F. F.Chen, 2n=2x= 16) according to morphological differences, significant reproductive isolation, isozyme band differences, chromosome number and karyotype differences.

Chen Qingfu (1999a, b, 200 1, 2004) thinks that according to the evolution law of common plants, perennial, diploid and cross-pollinated wild buckwheat is more primitive than annual, diploid and polyploid, and cross-pollination has different styles than self-pollination with the same length.

Sweet buckwheat and bitter buckwheat have different origins, and their ancestors may be wild buckwheat and hairy buckwheat. There are significant differences between buckwheat and buckwheat in chromosome size, karyotype characteristics, isozyme spectrum characteristics and morphology, and they should have different origins. Their esterase and aspartate aminotransferase isoenzymes appear in the enzyme bands of wild buckwheat and wild buckwheat respectively. There are also obvious differences in chromosome size and characteristics between wild buckwheat and wild buckwheat, which are similar to sweet buckwheat and bitter buckwheat respectively. The main characteristics of tartary buckwheat, such as the furrows on achenes and the same style length, can be found in wild buckwheat, and the main morphological classification characteristics of sweet buckwheat can also be found in wild buckwheat. Moreover, sometimes individual plants separated from buckwheat population and wild buckwheat population have relatively developed woody rhizomes and similar perennial characteristics, which may indicate that they may come from perennial types. However, after the original cross-pollination types of different styles were introduced to cold regions, due to low temperature, pollination, mutation and genetic variation, a self-pollination type of tartary buckwheat was formed, which could adapt to the same length of cold styles.

The interspecific phylogeny of Fagopyrum is shown in figure 14- 17.

Fig. 14- 17 interspecific relationship of buckwheat large grains.