Botanical characteristics and total flavonoids content of Pogostemon cablin（Blanco）Benth.‘Gaoyaoensis’ produced in Zhaoqing

【Objective】The differences in the total flavonoid content and antioxidant activity of different parts of Pogostemon cablin（Blanco）Benth.‘Gaoyaoensis’were analyzed. And the suitable traits and the quality of the medicinal parts were evaluated to provide scientific basis for scientifically formulating the planting technical regulations of P. cablin and improving the medicinal quality.【Method】Taking the three-year-old P. cablin as the research object，observed and recorded the botanical morphological characteristics of roots，stems，leaves and other main vegetative organs. The water content，total flavonoids content and DPPH free radical （DPPH·）scavenging ability in stems and vegetative organs of different leaf ages and years were determined，and the medicinal quality of each part was comprehensively analyzed.【Result】The stems of P. cablin were divided into erect stems and stolons，usually the 4^th to 10^th nodes had obvious aerial roots or prominent roots. The main stem was prostrate，corrugated，densely lenticels. The opposing leaves，axillary buds and aerial roots of the upright stem nodes generally grew cooperatively. The whole leaves were densely velvety epidermal hairs or glandular hairs，and some stolons had 1 to 2 upright stems with branches greater than 90°. The plants were tufted. The water content of different leaf ages was tender leaves>climax leaves>old leaves. The water content of stem segments in different years was annual stems> biennial stems>triennial stems. The order of water content of vegetative organs was leaf>stem>root. All parts of P. cablin contained flavonoids. The total flavonoids of each part of the plant was tender leaves>climax leaves>old leaves>annual stems>biennial stems>triennial stems>roots. The total flavonoids in leaves was 6.86±0.04 mg/g，which was 8.07 times as that of roots and 2.36 times as that of stems respectively. The DPPH · scavenging rates of leaves and stems were 90.71% and 37.53% respectively，while that of roots was only 15.61%. It showed that the antioxidant activity of patchouli was：leaves>stems>roots.【Conclusion】The botanical characteristics of P. cablin produces in Zhaoqing are more conducive to its lush growth. According to the difference in total flavonoid content and antioxidant activity of stems and leaves are of different leaf ages and years，the medicative part of P. cablin is the best in leaves，stems second，and roots the worst. Combining with the tradition that P. cablin is harvested from whole plant or above ground，it is recommended to harvest the P. cablin planted in the current year，remove the old stems of the root and take the tender leaves，climax leaves and annual stems as medicine.