Floral biology and seed production in cultivated North American ginseng (Panax quinequefolius)

Morphological characteristics of flowers, duration of flowering, degree of self-pollination, and extent of berry and seed production in North American ginseng (Panax quinquefolius L.) were studied under controlled environment al conditions as well as under field conditions. A comparison was also made between plants of 3 and 4 years of age at two field locations. The duratio n of flowering was 3 weeks and was similar in plants of both age groups gro wn in the two environments; however, 4-year-old plants produced an average of 40% more flowers (100 per plant in total) compared to 3-year-old plants, Flowers were comprised of five greenish-colored petals, five stamens, and an inferior ovary consisting of predominantly two fused carpels and stigmat ic lobes, Anthers dehisced in staggered succession within individual flower s, and flowering began with the outermost edge of the umbel and proceeded i nwards, At any given time during the 4-neek flowering period, 10% of the fl owers in an umbel had recently opened and mere producing pollen, Stigma rec eptivity was associated with separation of the stigmatic lobes; this occurr ed at some time after pollen release. Growth of pollen tubes through the st yle in naturally pollinated flowers was most evident when the stigmatic lob es had separated. The proportion of flowers that developed into mature berr ies (pollination success rate) was in the range of 41% to 68% for both 3-ye ar-old and 4-year-old plants. However, when the inflorescence was bagged du ring the flowering period, berry formation was increased by 13% to 21% in 4 -year-old plants, depending on location. 4 majority of the berries (92% to 99%) contained one or two seeds in an almost equal frequency, with the rema ining berries containing three seeds. In l-year-old plants, the frequency o f two-seeded berries was increased by 13% by bagging the inflorescence, The se observations indicate that P. quinquefolius is highly self-fertile and t hat several physiological and environmental factors can affect seed product ion.