Thank you for all your guesses, a vast majority of which were right on the mark. Bloodroot, Sanguinaria canadensis, is one of the first spring ephemerals to bloom. On sunny days its petals are open wide, closing at night when the temperature drops and on cloudy, rainy days (when pollinating insects are less apt to visit). Only pollen is produced by Bloodroot – no nectar. Even so, insects, especially mining bees, visit and collect pollen, and in the process often pollinate the flower.
The methods which Bloodroot employs in order to become pollinated are impressive, to say the least. While cross-pollination is preferable, self-pollination is better than nothing. To limit self-pollination, the female stigma becomes receptive before the male anthers of the same flower produce pollen. Furthermore, during the first few days of the flower opening, the anthers bend downward toward the outside of the flower, away from the receptive stigma, where they are easily accessible to insects. If insect pollination doesn’t take place by the third day of flowering, however, the anthers bend inward, contacting the stigma and self-pollinating the flower.
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