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Posts tagged “Pollinia

Showy Orchis Flowering

6-4-14 showy orchis 267A walk in deciduous woodlands at this time of year could result in the sighting of several species of orchids, one of which, Showy Orchis (Galearis spectabili), has a stalk of several flowers which typically bear lavender hoods (one variant is white). Potential pollinators, most of which are long-tongued bumblebees, butterflies, moths and bees, land on a white petal below the hood which acts as a “landing pad.” The insect next heads for the tip of the nectar-filled spur located at the back of the flower. In getting there it brushes against, and often picks up, packets of pollen (pollinia) before moving on to the next blossom, where cross-pollination ideally takes place. (Thanks to Ginny Barlow for photo op.)

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Common Milkweed Pollination

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The structure of the Common Milkweed (Asclepias syriaca ) flower is such that its pollen, produced in two saddlebag-like sacs with a black appendage joining them, snaps onto an insect’s leg when the two come in contact with each other. To assure that the chances of this are high, the pollen sacs (pollinia) hang inside a slit that is located between each of the five cups, or hoods, that contain nectar. An insect lands on the slippery flower, attracted by both the scent and availability of nectar, and inadvertently one or more of its six legs slips down between the hoods into a slit, where the pollinia automatically attach to the leg. The insect withdraws the leg upon leaving to find more milkweed nectar, and the attached pollinia eventually falls off onto another milkweed flower, pollinating it. Unfortunately, about 5% of milkweed flowers visited trap insects because they cannot extract their legs from the slit. It is not uncommon to see an insect dangling from a Common Milkweed flower – during a 30 minute visit to a milkweed patch recently I released 2 flies, 3 skippers (butterflies) and one honeybee that were caught, but hadn’t yet perished.