Exploration of cytomorphological diversity in the members of polypetalae from lahaul spiti and adjoining areas

Abstract

Present work pertains to cytomorphological studies in the plants of Polypetalae from the cold deserts of Lahaul-Spiti and its adjoining areas. The area remained covered with snow for more than 6 months. Temperature during winter falls as low as -300 C. Air is very dry and strong winds blow almost throughout the year at higher elevations. The mountain ranges here consist of rugged mountains, snow clad peaks, bare rocks, and steep sandy slopes with rock gravels. As a consequence of harsh climatic conditions prevailing in the region, plants tend to become prostrate, thick, hairy, bushy, hardy, sturdy, mat and cushion forming, and spiny with long roots and small succulent or woolly leaves. Majority of the plants perennate through rootstocks, runners, bulbs, rhizomes and tubers. The area is under considerable pressure of human intervention and natural disasters which include agriculture, heavy grazing, snow avalanches, windstorms, landslides, increasing entry of tourists and transport vehicles, and overexploitation of medicinally important plants. So far no serious attempt has been made to explore the cytomorphological diversity in the flora of Lahaul-Spiti and its adjoining high altitudinal areas. Present cytomorphological investigations included 140 species belonging to 72 genera. All the species have been studied meiotically for the first time from the area. Chromosome counts in 14 species are the first ever reports. As many as 41 species have been counted chromosomally for the first time from India. Chromosome counts in seven species are the first ever records at sub-species/variety level. New intraspecific diploid or polyploid cytotypes are recorded in 13 species. New intraspecific aneuploid cytotypes (indicated as in bold) are recorded in eight species. Presence of variable number of B-chromosomes are recorded for the first time in Sedum oreades (n=11+0-4B) and Delphinium vestitum (n=8+0-1B). Morphogenetic variation are detected in some species are attributed to ploidy level. On the other hand, the morphovariation in Geranium wallichianum, Impatiens thomsonii (Thalictrum foetidum) seem to have a genetic basis.