| Primula merriiliana Schltr. and Primula cicutarrifolia Pax. are two rare and endangered plant species endemic to China. Because of a rapid decrease in quantity and distribution areas for the two species, P. merriiliana is only found in south of Anhui province, while P. cicutarrifolia occurs sparsely in the United regions of southern Anhui, the north of Zhejiang, Hubei and the near areas . The reasons that caused these two species toward rarity and danger still remain unknown.This investigation of the two species is mainly dealing with their morphological characters, population biology, pollination biology and molecular biology, based on the following methods such as section slides, SEM, artificial pollination, RAPD analysis and gravity glass slides . This study is intended to demonstrate the distribution patterns of the populations for the two species, the numerical and spatial characteristics of ecological difference, the biological characters of seeds, pollination mode and reproductive stratigies, and molecular genetics. In light of the results from this study, the reasons that resulted in the present dangerous situation for the two species were discussed , and the suggestions for protecting them were proposed . The conclusions are as follows:1. Primula merriiliana is a small plant of biennial, rosette herbs with pinnately dissected leaves. The flowers are borne on leafless scapes in umbellate inflorescences, which are arranged in the form of 1-3 level of the umbels. They are often heterostylous, whereas P. cicutarrifolia is different from the former in having homomorphic flowers, one level of umbel, and the eroded tepals. Both of them sprout in August every year and die in July next year.2. The leaf epidermis of the two species has slight curicular and a few of stomata. Their root system and vascular bundle are slim and fragile so as to be vulnerable to damage produced by changing of environment conditions.3. The two species are suitable for growing in the cool, moist habitat with alkaline soil and sensitive to water. The distribution of the two species is very narrow and tends to decrease. Now the populations of P. merriiliana are distributed in patch in the south of Anhui, such as Huangshan, shitai, Yixian, Xiuning, Ningguo et al., and the populations of P. cicutarrifolia exhibit clumped distribution in Zhejiang, Hubei, Jiangxi, Anhui etc. Furthermore, the population size is small, and its number is scare , and every population isn't dominant in its community, which resulted in their endangered state, for which habitat fragment and artificial damage are mainly responsible.4. The two species are crossly pollinated by insects, and the role of wind-pollination could be ignored because the pollen quantity decreased rapidly with the increasing distance.The major pollinators are tripidae and some other insects, which belong to Hymenoptera and Lepidoptera, respectively. These insect visitors are important for reproductive success of the two species because their seed-set is not high without pollinators' visiting. The styly of thrum flower of P. merrilliana is about twice as high as that of P. cicutarrifolia. Moreover, the thrum papillae are frequently longer and also more crowded than the pin papillae, whereas the size of pollen of P.merrilliana is 1.6 times that of P. cicutarrifolia. The seed-set by legitimate union is higher than that by illegitimate union. As to pollination effect, the seed-set of P. cicutarrifolia usually depends on pollinator visiting, but selfing will be favored in the stressed environment. What's more, the ovule abortive events of the two species is evident, which may be one of the threatening factors. From study on their floral syndrome, it is possible to ascertain that P. meirilliana and its sister species P. cicutarrifolia have the same ancestor that is homostylyed, since the changing of environment conditions or visiting by insects, P. merrilliana becomes heterostylyed and seems to have envolved in a direction toward dioecy or subdioecy.5. Random amp...
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