Abstract: The distribution characteristics and content change laws of rhubarb polysaccharide in the rhizome of Rheum palmatum were studied by histochemical methods and phenol-vitriol colorimetry. The results were described as follows: The distribution of rhubarb polysaccharide in the rhizome had a multilocus character. Rhubarb polysaccharide shows different distribution in the periderm, cortex and parenchymas of secondary vascular tissue and pith. The xylem parenchymas of the secondary xylem and the phloem parenchymas of the secondary phloem are the chief tissues that accumulate and store rhubarb polysaccharide. During different growth periods of rhizome, the total content of rhubarb polysaccharide in the rhizome and its tissues increased gradually with growth of the plant but decreased slightly in a later period. Rhubarb polysaccharide content is greater in phloem parenchyma than in xylem parenchyma. The mode of rhubarb polysaccharide production is gradual accumulation and storage. The secondary vascular tissues are the chief tissues that accumulate and store rhubarb polysaccharide in rhizome.

Key words: distribution, Rheum palmatum, rhizome