ACHENE MICROMORPHOLOGICAL CHARACTERISTICS AND TAXONOMIC SIGNIFICANCE IN LEONTOPODIUM R. BROWN EX CASS. TAXA (ASTERACEAE: GNAPHALIEAE) IN CHINA

Leontopodium R. Brown ex Cass.belongs to the tribe Gnaphalieae in the family Asteraceae; it comprises approximately 60 species worldwide, of which 40 are distributed in China. The morphological characteristics of the achene are relatively stable and can be used as taxonomic criteria for species classification within Asteraceae. In this study, scanning electron microscopy (SEM) was used to observe the achene micromorphological characteristics of 28 species and 1 variety of Chinese Leontopodium. The results showed that the achenes of Leontopodium species were elliptical or narrow elliptical, approximately 0.7-1.6 -mm long x 0.1-0.6 -mm wide. The surface ornamentation was reticulate or rippled with clavate twin hairs or smooth. The carpopodium base was constricted or unconstricted. Based on these characteristics, we provided a new key for Chinese Leontopodium taxa. The characteristics of the achene trichome, surface ornamentation, and carpopodium show important taxonomic value at different taxonomic levels, leading us to arrive at the following conclusions. 1. The shape of the achene trichome is valuable for the taxonomic delimitation of taxa between Leontopodium and related genera. 2. The achene surface ornamentation can be categorized into two types and is a taxonomic tool for classification at the section level within Leontopodium. 3. The characteristics of the carpopodium and trichome density can serve as important features under the section level. Thus, achene micromorphological characteristics provide significant morphological evidence that could play an important role in resolving various taxonomic problems within Leontopodium and among related genera in Asteraceae.