Abstract
Seedling characteristics of Pongamia pinnata (L.) Pierre are described. Its seeds were collected from a tree growing in the Campus of University of Karachi and germinated without any dormancy breaking treatment in pots filled with garden sandy loam soil maintained at 75% MWHC. The seeds were sown in surface layer of soil not below than 1 cm. Seedlings of 10- and 60 days were studied. The seedling was of Phanerocotylar – Epigeal Reserve type. The major allocation of biomass in 10-day old seedlings was in cotyledons followed by leaves, roots and stem. Tap root had profuse laterals. Cotyledons large, more or less sessile, green fleshy –food laden, concave inside and convex outside, with no visible venation and retained with the seedling for some 50 - 60 days after emergence. The hypocotyl short, green, shining. Epicotyl longer, pubescent. The basal stem may sometimes be pruinose. The primary leaf simple, alternate. There is a great irregularity with respect to the first appearance of imparipinnate trifoliate leaf with ovate leaflets. It may arise after 2, 4 or 6-7 simple leaves. Leaf stipulate, apex acute (at times acuminate, basally obtuse. Aspect ratio 0.6 - 0.67. Venation brachidodromous. Angle of divergence (AOD) moderate between 1o and 2o veins and wide between 2o and 3o veins. Areole small and veinlets endings linear. There were four types of trichomes on very young stipules and leaves – 1) Short flat, bent near base, curved, brown, pointed-at-the-apex and unicellular, non-glandular trichomes, 2) Septate multicellular non-glandular trichomes, 3) Very long and thin non-glandular trichomes and 4) Stalked capitate uniseriate filiform non-glandular trichomes. Leaves multistomatic ventrally; dorsally generally devoid of stomata except few rarely. Stomata were identified on the basis of Prabhakar (2004). Paracytic, anomocytic, staurocytic, tetracytic and anisocytic stomata were present on the inner surface of cotyledon. Hypocotyl had paracytic stomata. Epicotylar stomata included paracytic, anisocytic, anomocytic and anisotricytic types where as paracytic, anisocytic, anomocytic, staurocytic and tetracytic characterized the ventral surface of leaf. Paracytic type of stoma characterized P. pinnata and was common amongst all the organs. Abnormal stomata included paracytic stomata with common subsidiary and contiguous paracytic stomata with no subsidiaries. Paracytic hemitricyclic stoma was also present but very rarely. Stomata density on ventral surface of leaves averaged to 211.59 ± 2.60.mm-2 and anomocytic stomata were larger than the paracytic stomata.
