Study on Distribution, Habitat Characteristics and Seed Morphometry of a Medicinal orchid,Eulophia herbaceaLindl.

Abstract

Eulophia herbacea Lindl. is a beautiful orchid species with medicinal importance. Loss of habitat and illegal collection of tubers have resulted in gradual decrease of its natural populations. Since formulation and successful execution of conservation strategies in such declining species highly depend upon information regarding their distribution, habitat preferences, percent fruit set and seed dispersal ability, present study was planned to document such details of E. herbacea in Himachal Pradesh. Field surveys across the state revealed that this orchid was restricted in distribution (1446–1925 m) to five localities of Solan district. It inhabited open grasslands with sparsely shrubby elements. The population density was found highest (4.94±2.68) at Shaktinagar and lowest (2.38±0.98) at Kathlighat. Slightly acidic soils (pH 5.77±0.59–6.62±0.41) with high contents of organic C, P and K were best suited for its growth and development. Percent fruit set was low (42.50±2.85) and the spindle shaped seeds were very small in size (0.69±0.05×0.11±0.02 mm). Scanning electron microscopy (SEM) revealed that the testa cells were spirally arranged, and their periclinal walls possessed thin and oblique external ridges. The embryos were rather tiny; about 80% seed space was occupied by air thus making them buoyant. The localized distribution of this species in Himachal Pradesh seems to be related to high habitat specificity and complex nutritional requirements.