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Posts tagged “Quercus rubra

Oak Catkins A Source Of Protein

5-14-18 gray squirrel eating oak flowers2 _U1A2327It’s common knowledge that you can often find warblers at this time of year by looking up into flowering oak trees, as the male flowers (catkins) attract an important source of protein for birds in the form of insects. Oaks (all parts) are host to more than 550 species of butterfly and moth larvae as well as many other invertebrates, many of which are attracted to catkins.

It turns out that birds are not the only creatures that visit oak catkins in order to secure a meal. Although we think of Gray Squirrels as consumers of nuts, seeds, fruit and fungi (and bird eggs and fledglings), their preferred food in the early spring includes the nutritious buds and catkins of oaks, elms and maples. Apparently their taste buds are not the same as humans’, as people who have consumed catkins say that their taste leaves a lot to be desired. (Photo: Gray Squirrel eating Red Oak catkins. Thanks to Sadie Brown for photo op).

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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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More Buds

2-24-16 buds  019

The previous “bud scale” post engaged readers to an extent that made me feel another post with additional buds to scrutinize would be welcome. Apologies to non-woody plant aficionados!

When identifying woody plants in winter, one takes advantage of everything a tree or shrub has to tell you: bud/branch arrangement (opposite/alternate), bark, silhouette and terminal buds. Buds are so revealing that they alone can immediately tell you what species you are seeking to identify. Is there one bud at the tip of each branch (willows) or multiple terminal buds (red oak)? Are there bud scales (no-witch hazel; yes- bigtooth aspen)? If so, what are their number (willows – one) and arrangement (overlapping, like shingles – red oak)? Are the buds red (striped maple), brown (witch hazel), yellow (bitternut hickory), green, or some combination of these colors? Are they pointed (bigtooth aspen) or rounded (willow)? Every species of tree has buds with a unique combination of these characteristics.  Now is the time to observe them, as some will soon start to open.

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Northern Red Oak Buds

12-23-14  red oak terminal buds IMG_6865There are approximately 600 species of oaks in the genus Quercus, all of which are in the Beech family. This genus has two subgroups, the red oaks and the white oaks. The leaves of trees in the red oak group have sharply pointed lobes with bristles. The white oak group has leaves with rounded lobes lacking bristles. Although usually there are some leaves on an oak tree that persist well into the winter, it is helpful to be able to identify a species by its buds alone. Oaks tend to have multiple terminal buds. Northern Red Oak’s terminal buds are large, pointed, cone-shaped and covered with reddish-brown, mostly hairless scales that overlap like shingles, with one edge covered and the other edge exposed.

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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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Northern Red Oak Identification in Winter

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While identifying an oak species by the shape of its leaf is fairly easy, there are other characteristics in winter, when leaves aren’t available (except under the snow), that serve as clues to an oak’s identity.  A mature northern red oak can be readily recognized by its bark — its ridges appear to have shiny stripes down the center.  The buds of northern red oak are also distinctive.  Like most oaks, red oak’s terminal (located at tip of twigs) buds occur in clusters.  Northern red oak’s terminal buds are conical, and are a reddish-brown color.