Transverse section of Zingiber officinale leaves: the upper epidermal cells are more neatly arranged, the upper and lower surfaces are hairy, and the lower surface is more hairy. The fenestrated tissue of the leaf flesh is 3-4 columns of cells, and the spongy tissue is lax. The main vein vascular bundles external tough type, crescent-shaped or "U" shape, "U" shape of the concave part of the other 1 ~ 5 smaller vascular bundles, around the thin-walled cells can be seen texture holes; the upper and lower epidermis in the inner side of the columns of thick horn cells. 1. Herbal source: the leaves of Bauhinia verrucosa, family Verbenaceae. 2. Operation: take 1g of powder, degrease with petroleum ether, filter, add 10ml of ethanol to the residue, soak overnight, filter. Concentrate the filtrate to 1ml, add 2 drops of concentrate in each of 2 test tubes, then add hydrochloric acid-magnesium powder and hydrochloric acid-zinc powder reagent respectively, which will show orange-yellow and cherry-red color in turn. (Check for flavonoids)