Seedling phenology of Ecbolium ligustrinum exhibiting epigeal phanerocotylar type of germination

Ecbolium ligustrinum (Vahl) Vollesen (Acanthaceae) is characterized by some special features in its seedling phenology and germination. After suitable scarification seed takes 7-8 days for inception of germination. The hypocotyls exhibit rapid growth leads to lifting of seed coats with emerging cotyledons indicate epigeal pattern of germination. These cotyledons at 13-14 DARE, are completely emerged out and seed coats are fall off from the germinating seeds show signs of the phanerocotylar type of seed germination. Thus, the germination is of epigeal phanerocotylar type. The cotyledons are green, fleshy, photosynthetic and considered as paracotyledons. At 16-17 DARE emergence of plumule is recognized which is again marked as the completion of germination phase and onset of seedling phase. The 2nd and 3rd pair of foliage leaves emerges at 25-26 and 36-37 DARE respectively. These three (1st, 2nd and 3rd) pairs of foliage leaves are quite different in their shape, size, margins and venation pattern from the adult leaves, indicates the occurrence of eophylls. The seedling phase is completed by 154-168 DARE with the formation of 12th node with 11th pair of foliage leaves and by the abscission of those three pairs of eophylls. Though the epigeal phanerocotylar with foliaceous cotyledons (EPF) type of seedling shown by the species is quite common among dicotyledons, the seedling of the species is characterized by some notable morphological features like thickened hypocotyl, a pair of phanerocotylar epigeal cotyledons and three pairs of eophylls in opposite decussate phyllotaxy. Individual eophyll is ovate in shape with slightly dentate margins and acute to sub-acuminate apex. The eophylls are easily distinguishable from the foliage leaves of adult individual by their shape, size and venation pattern. Such specific features are very much helpful for identification of a species at its juvenile stage before flowering and fruiting. Thus, phenological studies of the seedling of widely used medicinally important plant species provide the great opportunities for their successful conservation in natural habitat.