Abstract

In this reserch, the morphology of leaf hairs, netlets and flowers, the development of flowers as well as molecular phylogenetic of the genus Onosma were comparatively studied based on literatures and specimens. The main results are as follows:

1. The classification of Onosma in China and Pan-Himalaya was revised, 52 species, 1 subspecies and 3 varieties were recognized in this region. 95 names were verified, including 82 species, 1 subspecies, 11 varieties and 1 form. Onosma lhokaensis Y. He & Q. R. Liu, was found new to science (paper is under review) and 7 names were treated as new synonyms.

2. Leaf hairs of 31 Onosma species were examined with scanning electron microscope (SEM). The results revealed that leaf hairs of Onosma were usually with basal stalk, which were constructed of one cell or many cells. The type and density of hair had apparent difference, which could be used to solve some taxonomy problems.

3. Nutlets of 33 species in Onosma was observed with micro-lens with DSLR and scanning electron microscope. The results showed that the shape, color and surface ornamentations of Onosma nutlets were highly diverse, three main types could be recogonized:

Type 1: Color brown to dark brown, lustreless, usually wrinkle, strumae or verrucate and the micro-protuberance appears verrucate, aculeate orstrumae;

Type 2: Color all kinds, from pale grey to dark brown, lustrous, usually wrinkle, sparsely strumae or verrucate and the micro-protuberance appears undulating;

Type 3: Color light yellow to light brown, smooth and lustrous, the micro-protuberance appears reticulate.

Geometric morphometrics study show that the width of nutnets, the shape of peak and the absence of stipitate cicatrix could be used to identify some similar species.

4. Flower development in 2 species of Maharanga, 2 species of Onosma, 1 species of Echium, were observed by SEM. Bilateral symmetry cannot be observed in the mature flowers of Maharanga, which was supposed to be an importent character for the indepence of this genus .  there was no significant difference between Maharanga and Onosma.

5. The flower characters of 19 taxon of Onosma were investigated. The results revealed that hairs on the inner surface of corolla, degree of anthers protruding, position of filaments, hairs at the base of filaments, degree of style and hairs on the surface of style were different between species, so those could be used as important characters to classify different species.

6. In the systematic analysis, all Onosma species were resolved as monophyletic clade, sister to the clade formed by Arnebia and Echium. Within the genus Onosma, two major clades were formed. One clade contained most species from Europe, Central Asia, Northern Pakistan and Xinjiang Province, China. The other contained species mostly from Pan-Himalaya. The genus Maharanga, which was separated from Onosma in Flora of China (Zhu et al., 1995), was not supported by molecular data, because all 3 species were resolved as a monophyletic clade which inserted among species from Pan-Himalaya region.