Polemonium vanbruntiae probably reproduces both vegetatively and sexually, although the relative importance of each is not known (and probably varies from site to site).
Plants spread vegetatively by means of horizontal rhizomes, and it may be that large clones are formed in this manner. A preliminary investigation by Elizabeth Thompson in one Vermont population showed that numerous stems were connected underground. The size of the clone was not determined but it may have been as large as several tens of square feet (hundreds of stems). In the same vicinity were observed plants that had clearly originated sexually (they were discrete plants or clumps). Other biologists have not observed obvious clonal behavior; in Maryland, Ed Thompson describes plants as clumped, suggesting that clones are quite small.
The pollination biology of the plant is unknown, but Popp (1990) describes the species as a self-incompatible perennial which is probably bee-pollinated. Both Ed Thompson (1990) and Elizabeth Thompson have observed bumblebees (Bombus sp.) visiting flowering plants. Flowers are protandrous (at least in one Vermont population), a possible outbreeding mechanism.
Seeds have been successfully grown under greenhouse and garden conditions. William Brumback of the New England Wild Flower Society collected seeds in Vermont in 1986. They did not germinate well immediately, but germinated well outdoors when held dry under refrigeration until the following spring (1987). Seeds held dry under refrigeration until November 1987 also germinated well outside. Other germination experiments with these seeds were erratic (Brumback 1989). Seedlings from these experiments have been transplanted into the wild in Vermont and have survived a single growing season with mixed results (Popp 1990). Long-term monitoring of this experiment will provide valuable information on the biology of the species.
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