A flat cylindrical bending and dried roots, both ends obtuse or slightly pointed, 3 ~ 10 cm long, 1 ~ 2 cm diameter, appearance maroon, has close links, the top has a bud or remnant stem scars, residual fine hard fibrous root or root white mark on both sides.Hard brittle and easily broken, reddish brown or russet, near the edge of vascular bundle in a ring in white dots.No gas, taste buds acerbity.With thick, hard, section reddish brown, without root is preferred.This product in the medicinal material goods, xi said “grass river car” or “floor”, but “river of grass”, “hail floor” for fleas Hugh’s name, read the article “fleas Hugh”.Microscopic identification: root transverse section: cork layer for series cork cells, dark brown.The cortex is wide.Arrange ring type outside vascular bundle tenacity, intermittent, or phloem lateral with fiber bundles.The marrow.This product parenchyma cells contains more calcium oxalate crystal and starch grains.Powder: light brownish red.(1) the calcium oxalate crystal diameter 15-75 microns;Containing crystal cells rounded, slightly thick wall.(2) the bordered pit catheter, with reticulate, scalariform and spiral duct, 12-72 microns in diameter.(3) wooden fiber bundle, fusiform, 12-18 microns in diameter, the wall is a bit thick, pit is obvious;Compound grain is composed of 2-4 points granule.(4) single grain starch class round or oval, umbilical point clear, short slit, dotted or herringbone, layer lines is not obvious;Compound grain is composed of 2-4 points granule.(5) suberized cell surface view class rectangle or irregular shape, wall slightly bent, a wall is a bit thick, some slightly renju shaped, and fine wrinkles.In addition, some thin wall cells full of yellow, yellow brown or reddish brown.