|其他摘要||With about 500 species worldwide, Pedicularis L. is a lineage of hemiparasitic flowering plants and occurs throughout the northern hemisphere. The greatest morphological diversity and species richness in Pedicularis are confined to a relatively small region of the Hengduan Mountains, where contains about half of species,in which two-thirds ones are endemic. However, due to the relative inaccessibility of the Hengduan Mountains region, many aspects of the basic biology of Pedicularis are poorly known, especially in their reproductive biology. In this paper, the reproductive mechanism of sympatric Pedicularis and pollination biology of P. lachnoglossa Hk. f. at high altitude were studied from Yulong Mountains,, and pollen morphology of Sect. Cyathophora, which is endemic to the Hengduan Mountains, was also addresed. Major results of this study were summarized as follows:
1. It is common that more than two Pedicularis species occurred sympatrically in a small area in Yulong Mountains of Lijiang and the other areas of the Hengduan Mountains region. More notablely, they all have a flowering period ranging from June to August. In the four study sites, two sites were found to have five sympatric species and the other two have six ones. The sympatric species at different sites used different means to achieve reproductive isolation, including temporal isolation, floral isolation, ethological isolation and habitat isolation.
2. Pedicularis lachnoglossa Hk. f. is a typical high altitude species, which exclusively depend on bumblebees for pollen collecting and pollination. Bumblebees were not the specialized pollinators for P. lachnoglossa and other Pedicularis species, but they showed high flower-constancy on P. lachnoglossa in a single pollination trip. We found that the bumblebees were more absorbed in collecting pollen from P. lachnoglossa, although they might also occasionally visit other species for nectar. In the control experiments, we found that the bagged flowers did not produce fruits and seeds. Self pollen grains were compatible, but self-depression might exist; ovule or seed abortion was obvious in seed development; pollen limitation was not significant, but resource limitation was obvious. Flower display sizes were related to pollination ratios, which showed negative correlation. If flowers were not pollinated, flower displays would be enhanced and pollination attractiveness promoted. However, no correlation was detected between the inflorescences numbers per plant and the fruits set, which might be explained by seed abortion of geitonogamy.
3. Pollen morphology of seven species in sect. Cyathophora was investigated by scanning electron microscopy (SEM) and light microscopy (LM). Two different pollen apertures could be distinguished (i.e. trisyncolpate and bisyncolpate), which might be more advanced in Pedicularis. The possible relationships between pollen data and corolla types were discussed. Based on the comparison of habitat and pollen characters of sect. Cyathophora, we found that pollen evolution might be more complicated than previously expected.|