University of Windsor, Department of Biological Sciences, Windsor, Ontario, N9B 3P4 Canada.
Am J Bot. 1999 Aug;86(8):1160-7.
Arisaema dracontium (green dragon) is a perennial herb that is widely distributed in eastern North America. However, in Canada, at the northern edge of its distribution, the species is designated as "vulnerable" with respect to conservation status. In natural populations, seedlings are uncommon; the present study was undertaken in order to characterize seed and seedling properties in green dragon. Seeds were sampled from five sites, ranging from Ontario at the northern limit of the distribution range, to Louisiana in the south. Seed germinability ranged from 25 to 55%, depending upon source. Experiments indicated that neither the hard seed coat nor a water-soluble exudate from the seed was responsible for inducing or maintaining dormancy. Patterns of seed germination appear to reflect general climatic conditions at the sites where seeds had originated. Cold stratification at 3°C produced significantly greater relative germinability in all seed collections except the most southerly one, from Baton Rouge. These seeds also had a slower overall speed of germination. In contrast, germination of seeds from the most northerly site was promoted by cold stratification and occurred over a relatively brief period. Germination in alternating light and dark conditions decreased the speed of germination compared to germination in the dark, however exposure to light changed the phenology of germination by promoting development of adventitious roots and primary leaves in these seedlings.
莨菪叶乌头（绿龙）是一种多年生草本植物，广泛分布于北美东部。然而，在加拿大，分布范围的最北部，该物种被指定为“易危”保护状况。在自然种群中，幼苗较为罕见；本研究旨在描述绿龙的种子和幼苗特性。种子取自五个地点，从分布范围最北部的安大略省到南部的路易斯安那州。种子发芽率因来源不同而在 25%至 55%之间。实验表明，硬种皮或种子中水溶性分泌物都不是诱导或维持休眠的原因。种子发芽模式似乎反映了种子起源地的一般气候条件。3°C 的低温层积处理除了来自巴吞鲁日的最南部种子收集外，在所有种子收集物中都显著提高了相对发芽率。这些种子的整体发芽速度也较慢。相比之下，最北部种子的发芽受到低温层积的促进，并且在相对较短的时间内发生。与黑暗条件下的发芽相比，在交替的光照和黑暗条件下的发芽会降低发芽速度，但光照的暴露会通过促进这些幼苗的不定根和初生叶的发育来改变发芽的物候。
