Aspects of the Biology of Trientalis Borealis Raf

摘要: Three species and one subspecies of Trientalis are recognized in North America, but only borealis Raf., the northern starflower, occurs eastern America. The life cycle consists three distinct phases each year: shoot development, rhizome growth, tuber formation. Asexual reproduction by tubers is more important than seed. Of annual dry matter produced, 64.8% apportioned to asexual less 2% sexual tissue. Rhizome growth formation regulated photo—period; short days favor tuberization long growth. Tuber under field conditions began July, when photoperiod was about 15 hr. Cool nights warm were favorable for accumulation days. number degree—hours accumulated during development southern populations similar at sites 200 miles apart on a north—south gradient, occurred shorter period time site. Seedlings T. have not been found field, relatively high germination rates achieved laboratory conditions, Cold treatment increased percentage trientalis seeds. Ninety stratification delayed peak length before after seeds exposed room temperatures. duration same controls 30— or 60—day periods stratification.