[Study on morphological and histological identification of herba pogostemonis]

To identify two types of Pogostemon cablin (Guang Huoxiang), Shipai Huoxiang and Hainan Huoxiang.

Morphological and microscopical methods.

Long bag-like glandular hairs with one-cell head existing in the intercellular space are found in the cortex of stems, mesophyll and parenchyma of midrib. The glandular hairs with special large one-cell head and with a special short and small one-cell stalk, flat bag-like cuticle above secretory cell are caved in the forms of square, triangle, convex len and round-oids are also found in the surface of leaves and stems. The primary pholem fiber bundles with very thick walls are uncontinuous and arranged with a circle in the transverse section of stems; the perimedullary cells contain needle and prism crystals. Above-mentioned characters are differed from other plants of Labiate family. The old stems are cylinderoid forms, branch angles are usually smaller than 60 degrees, the surface of upper, middle stems and young leaves with purple colour are unusual, the palisade ratio are less than 10(5.05 and 9.26 cultivated seperatedly in Guangzhou and Gaoyao), in Shipai Huoxiang. But in Hainan Huoxiang, the old stems are rectangular cylinder, branch angles are usually over 60 degrees, the surface of upper, middle stems and young leaves are commonly purple colour, the palisade ratio are over 10(14.35, 13.18, 13.84 and 14.33 cultivated separatedlly in Wuchuan, Suixi, Leizhou and Hainan).

Above-mentioned characters may distinguish two types of Pogostemon cablin, Shipai Huoxiang and Hainan Houxiang.