Comparison of seed characteristics of six Panax species

To differentiate the seeds of Panax spp., we determined the surface morphology, length, width, thickness, 100-seeds weight, volume, density and microstructure of seeds of 6-Panax spp. [P. ginseng, P. notoginseng, P. quinquefolius, P. japonicus, P. japonicus var. and Jinping ginseng) and Jinping ginseng. Besides, we also studied the surface morphology, physical characteristics and microstructure of seeds of these 6-Panax spp. The seeds of P. japonicus and P. japonicus var. were smallest, oval, brown and yellowish-white, respectively. The larger seeds of P. notoginseng and P ginseng were milky white, while, those of P. quinquefolius were yellowish-white. Seeds of P. notoginseng appeared triangular-oval in shape, with soft seed coat. Seeds of P. ginseng were oblate, with a hard and wrinkled seed coat and an endocarp divided into inner and outer layers. Seeds of P. quinquefolius were oblate, seed coat was easy to peel and similar in size to P. ginseng, but were heavier in weight and endocarp was divided into inner, middle and outer layers. Seeds of Jinping ginseng were largest, yellowish-white, kidney-shaped and slightly flat. Seeds of 6-species of Panax differed in surface morphology, physical characteristics and microstructure for easier identification. This study provided a reference for seedd identification and a new method to classify Panax ginseng seeds from other species.