Pollination in Bleeding Hearts

Flower Structure Specialized for Unusual Pollination Mechanism

Nov 26, 2008

Pollen deposited from a flower's own stamen to its stigma rubs off onto the body of a nectar-searching bee, which carries it to another flower for cross-pollination .

Bleeding Hearts, Corydalis, and their Relatives, by Mark Tebbitt, Magnus Liden, and Henrik Zetterlund, is a mine of scientific information and an indispensable resource for those interested in these genera. Aside from the remarkable visuals and detailed species descriptions, there is a very interesting explanation of the bleeding heart’s unusual pollination mechanism.

This mechanism is a special case of a more general specialized mode of pollination. Joseph Wood Krutch, naturalist and essayist, writes in The Best Nature Writing of Joseph Wood Krutch, “Sometimes the flower is so constructed that, for instance, the insect cannot get at the nectar without brushing against the pollen-bearing anthers and then against a stigma, which will ultimately conduct the gene-bearing protoplasm of the pollen down to the ovules below.”

Pollination in bleeding hearts is dependent on the flower structure, which is unusual in three respects.

While flowers are still in the bud stage, stigma and anthers interlock. As the flower matures, the stamens are pulled downward, depositing pollen on the stigma. The stigma, due to its shape perhaps, is neatly hidden between the inner petals. Meanwhile, nectar accumulates in the hollow spurs at the bases of the two outer petals.

When a bee visits the flower, it pushes the hooded inner petals and stamens aside and sticks its head into the flower, long tongue reaching for nectar in the spurs. In doing this, the bee rubs body and head against the stigma, picking up some pollen. As the bee flies off, the hinged inner petals spring back, prepared for the next comer. The bee meanwhile transfers pollen onto the stigma of a new flower, resulting in cross-pollination.

Interestingly, pollen usually only germinates and results in fertilization when in contact with the stigma of a flower on a different plant. In some cases. however, a plant may self-fertilize, particularly if growing in an area where survival is difficult due to poverty of soil or nutrients.

Sources

Krutch, Joseph Wood. 1995. The Best Nature Writing of Joseph Wood Krutch. University of Utah Press, Salt Lake City.

Tebbitt, Mark, et al. Bleeding Hearts, Corydalis, and their Relatives. Brooklyn Botanic Garden and Tilmber Press, Portland, Oregon.

The copyright of the article Pollination in Bleeding Hearts in Botany is owned by Connie Ganong. Permission to republish Pollination in Bleeding Hearts in print or online must be granted by the author in writing.