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Leaves

Goldenrod Bunch Gall

goldenrod bunch gall 144Galls are abnormal plant growths that are caused by a number of agents, including insects. Each gall-making insect has a specific host plant and location (leaf, stem, bud) on which it lays its eggs in the spring, during the growing season. The egg-laying and/or hatching and chewing of the larva causes the plant to react by forming a growth around the insect. Galls of different species of insects vary in their shape and the gall maker can often be identified as a result of this.

Goldenrods are host to about 50 species of gall-making insects, two-thirds of which are midges, or tiny flies. Goldenrod Bunch Galls, also called Rosette Galls, are the result of an egg being laid in the topmost leaf bud of Canada Goldenrod, Solidago canadensis by a midge in the genus Rhopalomyia, often Rhopalomyia solidaginis. The stem of the goldenrod stops growing, but the leaves don’t. The resulting rosette of leaves provides shelter and food for the midge larva, as well as a host of other insects, including other midges. Adult Goldenrod Bunch Gall midges emerge from the galls in the fall, and females lay eggs in the soil. The larvae hatch within one to two weeks and spend the winter underground, emerging in the spring to start the cycle all over again. Interestingly, Rhopalomyia solidaginis lays all male or all female eggs, one or the other.

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February 14th

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Red-eyed Vireo Nest

10-31-13 red-eyed vireo nest  033 Abandoned bird nests are evident now that leaves have fallen off the trees. Consider the time and effort that goes into the construction of one of these single-use nurseries. Take the Red-eyed Vireo’s nest you see here lying on the forest floor. The female selects a nesting site — a time-consuming task, as the requirements are that it conceal the nest and provide shade for her young. (Too much sun will cause her to abandon the nest. One female who had selected a sunny spot was observed pulling nearby green foliage over her nest and fastening it in place with spider webs.) The female vireo then collects nesting material for the three layers of her nest: Exterior – tree bark, spider-egg cases, wasp-nest paper, lichen, green leaves and pine needles. (Nests exposed to sunlight may be decorated with light-colored tree bark such as birch bark.) Interior – bark strips and plant fibers. Inner lining – grasses, pine needles, plant fibers and animal hair. She then weaves these materials into a cup-shaped nest that is suspended from a forked branch by its rim. A trip for materials is made every 3 – 11 minutes and roughly twenty seconds is spent working each load into the nest structure. This intensive work takes the female vireo approximately five days – all accomplished without the aid of any hands or tools, and she only uses the result of all this work once. Fortunately, recyclers make good use of her efforts.

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Pitcher Plants Turning Red

10-29-13 pitcher plant2 158 Pitcher plant leaves are primarily green in the summer, tinged with red, but as summer turns into fall, many become deep red. Although this red color was thought to attract insects, it appears that this is not the case. The color change, according to research cited in the Journal of Ecology, is due to the level of phosphorus this carnivorous plant has received from its insect meals. There is a limited amount of phosphorus in a bog and plants living there acquire it in different ways. The pitcher plant acquires phosphorus from insects that it traps. It then utilizes the phosphorus to revitalize the (green) chlorophyll in its leaves for photosynthesis. The deep red color that the leaves turn in the fall indicates that the plant has not had a good meal in quite some time.

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Poison Ivy Thriving

10-24-13  poison ivy2  029Poison Ivy is in the Anacardiaceae family, which also includes cashews, mangos and sumacs. The sap of the stems, roots, fruit and leaves of many species in this family contains urushiol oil, which is what causes the allergic rash in 80% of humans that come in contact with these species. Poison Ivy is very sensitive to carbon dioxide, and even slightly elevated levels of CO2 have proven to increase its growth. In the past 50 or 60 years, during which time the amount of carbon dioxide in the atmosphere has increased by roughly 22%, Poison Ivy’s growth rate has doubled. The amount of urushiol oil has not only increased, but it is also more potent…leaves of three, let them be.

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Deciduous Leaves Falling

10-19-13 falling sugar maple leaf 081The falling of a leaf is the final step in an ordered series of events referred to as senescence. This process allows trees to conserve resources, prepare for a dormant period, and shed inefficient tissues. When leaves become unable to produce food due to a lack of chlorophyll, a process of shutting-down and sealing-off begins. Leaves are shed through a number of biological actions which take place at the base of the leaf’s stem, or petiole. The walls of some cells weaken, while those of other adjacent cells expand. The expansion of the latter causes pressure against the weaker-walled cells, resulting in these two groups of cells tearing away from each other, causing the leaf to fall. The tree forms a protective barrier on the wound where the leaf had been attached to the branch, sealing it off from pests and the environment and leaving a leaf scar.


Sundews Capture Their Meals

8-12-13 sundew & damselfly 060Sundews (Drosera spp.) are carnivorous plants often found in acidic bogs, fens and cedar swamps. They have numerous small leaves arranged in a circular, or rosette, pattern and they are covered with reddish, glandular hairs, or tentacles, that exude a sticky secretion at their tips. Insects, attracted to the glistening sticky droplets which resemble dew, land on a leaf and become stuck. The movement of the struggling insect triggers cell growth in the glandular hairs and they begin folding over the insect within 60 seconds. An anesthetic is released by the plant’s hairs, causing the insect to become motionless. Digestive enzymes are then secreted which liquefy the insect’s internal organs so that they can then be absorbed by the plant’s hairs. Although insect prey is not vital to sundews, the nitrogen the plants receive from the insects enables them to thrive in environments where nitrogen is in short supply. The damselfly pictured has been captured by a Round-leaved Sundew’s glandular hairs which have rendered it motionless and have started to grow and fold over the tip of the damselfly’s abdomen and its wings.

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