Aspects of the reproductive biology of clintonia borealis (Ait.) Raf.

Abstract

The rhizome of Clintonia borealis tAit.) Raf, was shown to store large quantities of total nonstructural carbohydrates up until fall dormancy and to draw upon these reserves during the spring growth period, however the level of decline and rate of decline are not necessarily the same from year to year. Older rhizome segments participate in TNG storage, demonstrating high levels in the fall and low levels in the spring. In addition, roots are also capable of storing TNG and probably provide an important secondary reserve. For a typical population in Northwestern Ontario, 3-leaved specimens were the most important members since they provided the greatest contribution towards the total population as well as the most flowering individuals. Plants with high leaf numbers produced the most rhizomes and were the ones most likely to be fertile. Population makeup, with respect to the number of plants in each leaf number category and the percentage of individuals in flower remains relatively constant from year to year for populations growing in a stable environment. Leaf number is determined in the fall by the number of preformed leaves present in the rhizome bud. Leaves which do not reach this level of development, i.e., primordial leaves, abort the following spring. Similarly an inflorescence in the bud must have matured enough to possess a well developed stipe before the onset of dormancy, otherwise it too will abort in the spring. Plants growing in open sites are most likely to be fertile. This phenomenon may be related to TNC storage since plants growing in the open are probably the most active photosynthetically and in turn producing the most TNC. A minimum or threshold level of TNC for inflorescence production in C. borealis is suggested. Insect mediated cross pollination is the principal pollination mechanism in Clintonia borealis; however, the species still possesses a capacity for self pollination. A distinct correlation exists between berry volume and the number of mature seeds contained. This is interpreted as a reproductive strategy allowing maximum seed dispersal by animal vectors since the most attractive fruit contain the greatest number of seeds.