Camellia sinensis (leaf)

Simple hairs occur on both surfaces of the leaf, but they are more abundant on the lower; the number, however, varies with the variety of tea, and with the age of the leaf; they are unicellular, tapering and rather thick walled, varying very much in length, but often attaining 500-700 microns.

The mesophyll is heterogeneous and asymmetrical. It is characterized by the presence of a large number of sclerenchymatous idioblasts. These are more or less branched and warty and often extend transversely from the upper to the lower epidermis. They vary much in shape and in the thickness of the walls. The cells of the spongy parenchyma contain cluster crystals of calcium oxalate.

The midrib is biconvex. Under each epidermis there is a layer of collenchyma of varying thickness. The wood is arched and the bast contains crystals of calcium oxalate. The meristele is surrounded by a pericycle consisting of slightly lignified cells arranged in circle. The cortical tissue contains idioblasts which are usually rather larger and more branched than those of the mesophyll.

The little fragments of the stems, which are often to be found in ordinary tea, have a slightly different structure. The wood in them forms a circle within which there is a pith containing branched idioblasts; these have comparatively thin, pitted walls.

The diagnostic characters of powdered tea are:---

• The characteristic hairs.
• The sclerenchymatous idioblasts, especially in petiole and midrib.
• The stomata surrounded by tangentially elongated cells.
• The calcium oxalate in cluster crystals.

Source: Greenish, H. et. al. (1908) An Anatomical Atlas of Vegetable Powders ^[1]

Source: Amy Brush Traditional Medicinals ^[2]