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- Author or Editor: R. Larry Peterson x
Primary and first-order lateral roots of Panax quinquefolius L. (American ginseng) were collected from plants in an experimental garden during their second year of growth and processed for light and transmission electron microscopy. Roots in primary growth had either a diarch or triarch primary xylem pattern, a pericycle, an endodermis with Casparian bands and subsequently a suberized cell wall, and a cortex of variable thickness with a suberized hypodermal layer. Both root types underwent rapid secondary growth and the primary root particularly formed a fleshy storage organ. The secondary phloem and secondary xylem had abundant parenchyma and few conducting elements. Secretory ducts differentiated in tissue derived from the pericycle and in the secondary phloem. Each schizogenous duct consisted of six to eight epithelial cells, which possessed dense, globular deposits but lacked starch. A phellogen, which produced several layers of suberized phellem, was initiated in the periphery of tissue derived from the pericycle. The results of this study clarify the anatomical localization of secretory duets in roots of this species.