Unground Alexandrian senna pods— Occur as flattened, reniform, membranous, leathery pods; green to greenish-brown with brown patches at the positions corresponding to the seeds; from 40 to 50 mm in length and at least 20 mm wide; at one end is a stylar point and at the other a short stalk. The pods contain six or seven flattened and obovate seeds, green to pale brown, with a continuous network of prominent ridges on the testa.

Unground Tinnevelly senna pods— Occur as flattened, slightly reniform, membranous, leathery pods; brown to yellowish-brown with brown patches at the positions corresponding to the seeds; slightly longer but narrower than Alexandrian senna pods, from 35 to 60 mm in length and 14 to 18 mm wide; at one end is a stylar point and at the other a short stalk. The pods contain five to eight flattened and obovate seeds, green to pale brown, with incomplete, wavy, transverse ridges on the testa.

Histology— Senna pods show epicarp with very thick cuticulized polygonal cells, occasional anomocytic or paracytic stomata, and very few nonglandular, one-celled, conical, often curved hairs, with thick papillose walls, from 100 to 350 µm in length; mesocarp consists of parenchymatous tissue containing a layer of calcium oxalate prisms and vascular bundles partially enclosed by fibers; endocarp with two crossed layers of fibers; seeds with a subepidermal layer of palisade cells with thick outer walls and endosperm of polyhedral cells with mucilaginous walls.

Powdered senna pods— Brown powder displaying polygonal cells with occasional small numbers of nonglandular hairs and anomocytic or paracytic stomata, fibers in two crossed layers accompanied by a crystal sheath of calcium oxalate prisms, isolated hairs, masses of palisade cells of the seeds, clusters, and prisms of calcium oxalate.