An online resource based on the award-winning nature guide

Cross-pollination

Bloodroot Pollination

4-30-15  bloodroot 084Thank 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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Showy Lady’s Slippers Flowering

6-23-14 showy lady's slipper 139As with Pink and Yellow Lady’s Slippers, one of Showy Lady’s Slipper’s three petals is greatly modified into a large inflated pouch called the labellum. The two other petals attract pollinators with an alluring odor, but the insects that enter into this pouch are in for a disappointment, as lady’s slippers produce little or no nectar. Once inside, visiting insects are guided by very fine, slanting hairs on the inner surface of the pouch towards the flower’s pistil and stamens. Once it has entered the constricted passageway that leads to the reproductive parts, an insect cannot turn around and must pass by the pistil and stamens. Lady’s slippers rarely self-pollinate, so it is crucial that they not only attract, but also extract pollen from insects to achieve cross-pollination. Thanks to their structure, this happens more often than not. The flowering of Showy Lady’s Slippers peaks in Mid-June in central Vermont; if you know of a nearby fen (peat wetland that gets its water from rainfall and surface water), best visit it soon, as that’s where you’re most likely to find this species of orchid.

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Pine Pollen: Nature’s Testosterone

6-12-14 pine pollen  100If you’ve noticed yellow clouds near pine trees recently, or a layer of yellow “dust” on your car or pond, you’ve witnessed the annual dispersal of pollen by male pine cones. Light and fluffy so as to be easily distributed by the wind (rather than insects), these minute pollen grains containing sperm cells can be found just about anywhere this time of year, including the nostrils of humans. All pines have separate male and female (seed) cones on the same tree. Male pine cones, which produce pollen, are much smaller, occur in clusters, are more papery, and remain on the tree for a much shorter period of time than most female pine cones. (By July they will litter the ground beneath pines before they quickly disintegrate.) Although it may mean a brief period of sneezing has to be endured by those allergic to it, this “golden smoke” not only creates beautifully intricate patterns for us to enjoy and makes it possible for pine trees to make the next generation of seeds, but it is also touted as an agent of increased testosterone and strong sexual libido, anti-aging, skin rejuvenation and improved immune systems for humans. Haste ye to a natural food store (or the closest pond!). (photo – Red Pine pollen & male cones)

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Trout-Lily’s Pollinators

5-7-14 trout lily pollinator IMG_1725Like Bloodroot and many other spring ephemerals, Trout-Lily (also known as Dog-tooth Violet and Adder’s Tongue) remains closed at night and on overcast days. On sunny days, bees are its main pollinators, but it is visited by many other insects, including Red-necked False Blister Beetles that feed on both its pollen and ovules.

When a bee visits a Trout-Lily flower, it usually removes half of the available pollen in one visit. In no apparent hurry, it often pauses in the middle of collecting to groom itself and pack pollen into the pollen baskets on its hind legs. It then heads directly back to its hive to unload the pollen. Unfortunately for the Trout Lily, this hampers cross-pollination, as it severely limits the amount of pollen that reaches other Trout Lily flowers. As compensation, Trout Lily has two sets of anthers – one set opens one day, the other opens the next, preventing a bee from collecting all the pollen from a given flower in one day, giving other insects the opportunity to cross-pollinate. (Photo: Red-necked False Blister Beetle)

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Jewelweed’s Cross-pollination Strategy

10-1-13 bumblebee and jewelweed  092Jewelweed (Impatiens pallida), also known as Touch-Me-Not due to the sensitivity of its bursting seed pods, illustrates a strategy used by many flowers to promote cross-pollination. The male and female parts of the flower develop sequentially — first the male (stamen), then the female (pistil), so that they are not mature and receptive at the same time. The bumblebee in this photograph is squeezing into the spur of a Jewelweed flower in order to reach the sweet nectar it contains. In doing so, its back brushes against the strategically located, pollen-laden anther (tip of male stamen). When the bee enters another Jewelweed flower, if its pistil is mature, some of this pollen is likely to brush against the stigma (sticky tip of the female pistil), thereby cross-pollinating the flower.

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Bottle Gentian Flowering

9-10-13 bottle gentian IMG_8093Bottle Gentian, Gentiana andrewsii, is one of our latest blooming wildflowers, and one of our most beautiful. Because its petals are closed so tightly, only bumblebees (pictured) and a few other insects have the strength to push their way inside the flower to reach Bottle Gentian’s sugar-laden nectar.

Like many other flowers, Bottle Gentian times the maturation of its reproductive parts to discourage self-pollination. Male pollen-bearing stamens mature first, and by the time the female pistil is mature, the stamens have gone by so the flower’s pistil can’t receive its own pollen (see central pistil surrounded by withered stamens in insert).

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Goldenrod Pollen

9-4-13 goldenrod pollen 305Goldenrod is an extremely important foraging plant for honeybees in the late summer, when its flowers produce prolific amounts of nectar and protein-rich pollen. Goldenrod pollen, the orange lump that you see packed into the pollen basket (after being mixed with saliva) on the hind leg of this honeybee, is often blamed for the allergies that many people experience in the late summer and early fall. It is falsely accused, however, as ragweed pollen is the real culprit. Being wind pollinated, ragweed has light, fluffy pollen, which is easily dispersed (and easily enters nostrils). Goldenrod pollen is large and sticky, allowing visiting insects to gather it (intentionally as well as unintentionally) all over their bodies and transfer it to other goldenrod flowers, therein cross-pollinating them.

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