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Posts tagged “Quercus alba

Oak Leaf Shapes & Sizes

11-15-16-oak-leaves-049a1752There are roughly 90 species of oak trees in North America, several of which can be found in New England. (Eastern White, Northern Red, Eastern Black, Burr, Common Chinkapin, Swamp White, Pin, Chestnut, Bear, Scarlet and Common Post). When identifying oaks, several characteristics, such as buds, bark, branching pattern and leaves, can be used. Most Northeastern species of oak have lobed leaves, with the lobes deep or shallow, pointed or rounded.

One thing all oak leaves have in common is their variability. Even on a single tree, you can find leaves of widely differing shapes. One reason for this is that the amount of sunlight that reaches them affects their shape.   Leaves that are shaded are not only often larger than those that are bathed in sunshine, but their lobes are far more shallow. Both of these traits maximize the intake of sunlight.   Canopies of oaks have a larger proportion of small, deeply-lobed leaves than lower down on the trees, where you can often find relatively large leaves that appear to lack lobes completely. The two pictured leaves come from the same Northern Red Oak.  Can you tell where on the tree they probably grew? (Thanks to Penny March for post idea and leaves.)

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Discerning Eastern Gray Squirrels

1-3-14 gray squirrel2 029In the fall, Eastern Gray Squirrels bury individual acorns from Red and White Oaks to sustain themselves through the winter. The acorns of Red Oaks have delayed germination – they can be stored up to six months before they start germinating. The acorns of White Oaks, however, have no such dormancy, and begin to germinate in the fall, soon after they fall from the tree. Once acorns sprout, they are less nutritious, as the seed tissue converts to the indigestible lignins that form the root. Gray Squirrels, as a means of “long-term cache management,” selectively remove the embryos from White Oak acorns (but not from Red Oak acorns) before burying them. Germination is prevented, and the storage viability of the White Oak acorns is extended by six months, equaling that of the Red Oak acorns.

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