Study of Floral Epidermal Features in Petrea Volubilis L. (Verbenaceae)

Petrea volubilis L. is an extensive perennial liana, upto 10 m high, stem ash coloured, covered with grayish pubescence. Leaves 14–16 X 6.5–8 cm, elliptic, scabrous above, pubescent on nerves beneath, flowers 2–2.3 cm long, showy, purple in pendulous, 1519 cm long axillary racemes, remarkable for large persistent star shaped calyx, rachis densely covered with soft whitish pubescence. Floral epidermal features including nature of epidermal cells, stomata and trichomes alongwith their dimensions of all floral parts are studied. Epidermal cells are polygonal, straight walled, papillose in peduncle, bract, deeply sinuate in calyx, broadly sinuate, papillose and straight walled in adaxial and abaxial corolla lobes respectively. Polygonal, elongate, straight walled in corolla tube, straight walled in stamen, carpel and fruit. In all organs cuticular striations are absent. Peduncle and fruits are astomatic, bracts and calyx are amphistomatic with anomocytic and anisocytic stomata in bracts and anomocytic in calyx respectively. Corolla lobes hypostomatic with anomocytic stomata. Trichomes are of two types non-glandular and glandular. Most of the organs are papillose. Trichomes vary in minute details. They are papillae, to unicellular papilloform to bi-tricellular ones. Glandular trichomes are sessile, short or long stalked with multicellular head with dense contents. Trichomes on corolla lobes are typical including tuberculate trichomes. Floral trichomes are found species specific and suggestive of their functional significance.