我国横断山区滇芎属植物花粉形态分化及演化趋势

POLLEN MORPHOLOGY DIVERSITY AND EVOLUTION TREND OF THE GENUS PHYSOSPERMOPSIS IN THE HENGDUAN MOUNTAINS OF CHINA

The genus Physospermopsis (Umbelliferae) included about 11 species. Among them P. hirsutula (C. B. Clarke) Farille, P. lalabhduriana Farille et Malla, P. bhutanensis Farille et Malla, and P. muktinathensis Farille et Malla are endemic in the Himalayas and with two species i.e. P. obtusiuscula (Wall, ex DC.) Norman, P. rubrinervis (Franchet) Norman widely distributed in both of the Himalayas and the Hengduan mountains of China. There are five species endemic in SW China, of which four species endemic in the Hengduan Mountains i.e. P. alepidioides (H. Wolff et Hand.-Mazz.) Shan, P. muliensis Shan et S. L. Liou, P. cuneata H. Wolff, P.forrestii (Diels) Norman and another species P. delavayi (Franchet) H. Wolff from the Hengduan Mountains extends to NE and C. Yunnan of China. This region belong to the Sino-Himalayan area. They grow at high altitudes from 2250m to 4800m and concetrate at altitudes from 2800m to 4000m. Pollen grains of five species were examined by LM and SEM. Pollen morphology of P. alepidiolides and P. muliensis are rhomboidal type. The basal leaves are entire or pinnate. The bracts and bractlets are entire or 2-3-lobed at apex. We support that they are primitive type in Physospermopsis. The pollen grains of P. rubrinervis and P. delavayi are mainly rectangular type. The basal leaves 2-pinnate. The bracts are pinnateand the bractlets trilobed at apex. These characteristics support the suggestion that they are advanced taxon in this genus. P. forrestii is mainly rhomboidal and rarely rectangular type. The basal leaves are 1-2-pinnate. The bracts and bractlets share incised-dentata. This species appear to be intermediat between above two taxa.