Acene and seed abortion contribute to the rarity of Kingdonia uniflora

Abstract

Studies of the development of the achene of the small perennial herb Kingdonia uniflora Balf. f. et W. W. Smith have shown that the early developmental of the achene, embryo, and endosperm are normal. However, from the middle of June, some of the achenes become abortive. The number of abortive achenes in a polymeric fruit increases during the later development stages. The abortive rate of the achene varies from 65.71% to 86.23% in different years. The abortive achenes are obviously smaller than the normally developed ones; in general, the embryo and the endosperm in the seeds attached to the abortive achenes stop development relatively early. It is very difficult to find mature fully developed achenes, and no seedlings were found in the habitat of this species. The success of sexual reproduction of K. uniflora is low. The low sexual reproduction success decreases the genetic diversity and, therefore, adaptability to the changing environment in the habitat of this species. These limit the expansion of the population of this species. We consider achene abortion to be the main cause of endangerment of K. uniflora.