PJB-2018-1698
Pollen morphology of genus Eritrichium Schrad. (Boraginaceae) from Pan Himalaya and China
Paras Mazari, Jia-Chen Hao, Quan-Ru Liu and Latif Ahmad
Abstract
The genus Eritrichium Schrad. comprises about 50 species, mainly distributed in Central Asia and Pan-Himalaya, with a few species in Europe and North America. There are about 43 species in China. The Infrageneric classification of Eritrichiumhas long been controversial and pollen morphology of Eritrichium species is still largely unknown. Furthermore, Boraginaceae is a eurapalynous and its complexity is rare in angiosperms especially in regard of pollen apertures. The aim of our study is to analyze the pollen morphology of Eritrichiumand to evaluate its taxonomic significance. In the present work pollen morphology of 32 taxa belonging to genus Eritrichium have been examined by using scanning electron microscope (SEM).
Generally, pollen grains very small to small in size, radially symmetrical, isopolar, 6-heterocolpate, (tricolpate and tricolporate) mostly perprolate, prolate, and rarely subprolate in shape, constricted at the equator rarely without constriction. Exine ornamentation was very uniform among all studied taxa i.e., psilate and perforated at poles only. However, the result showed great diversity within species in regard of the shape of pollen, type of aperture, number and position of pores etc. On the basis of these characters 8 pollen types have been recognized viz. E. laxum-type, E. axilliflorum-type, E. deqinense - type, E. oligocanthum-type, E. minimum-type, E. thymifolium-type, E.hemisphaericum type, and E. sessilifurcatum-type. All the studied characters provide information for correct identification of the morphologically similar taxa. The pollen data can also be helpful for distinguishing taxa, species-level revisions.
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