Ca2+, a versatile intracellular second messenger in various signaling pathways, initiates many responses involved in growth, defense and tolerance to biotic and abiotic stress. Endogenous and exogenous signals induce cytoplasmic Ca2+ ([Ca2+]cyt) elevation, which are responsible for the appropriate downstream responses.

Background: Rhynchostylis retusa (L.) Blume, commonly known as the fox-tail orchid, is a promising epiphytic native species for breeding programs. Its’ population is diminishing in the native habitat due to unscrupulous overexploitation and habitat destruction. Hence, conservation of this species attains prime importance. To achieve the foregoing task, phenotypic traits in relation to adaptation are to be elucidated. Methods: In the present investigation, the morphological characters were documented and the correlation between each trait was determined. Furthermore, the anatomy of leaves and roots was documented, as was the stomatal structure and distribution on the abaxile and adaxile surfaces of the leaves. Biometric features of floral characters and reproductive biology such as anthesis, stigma receptivity, pollen production per pollinium, pollen viability, pollination mechanisms, self and cross-compatibility; male sterility, etc. were studied and documented. Observations on capsule development, nature of seeds, seed viability, etc. were also determined. Result: The seed viability tests revealed that about 40% of the seeds are viable. The observations gathered during this investigation can be used to develop conservation, sustainable utilization and genetic improvement strategies for this crop.