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Bigtooth Aspen

Keeping A Dead Leaf Partly Alive

If you look on the ground these days as yellow Trembling and Bigtooth Aspen leaves are falling, you may notice that small splotches of green remain in some of them.  These chlorophyll-laden patches are usually found near the bottom of the midrib of the leaf.  If you open the pocket of tissue at the base of the green section, it’s highly likely you will find a minuscule (2 mm long) translucent caterpillar (a microscope may be necessary to detect it).

The caterpillar (larva) first bores into the stem, or petiole, resulting in a swelling. When it reaches the leaf blade it makes an elongated blotch between the midrib and the first lateral vein. The larva is capable of secreting a chemical which prevents the natural deterioration of the leaf.  As a result, chlorophyll is retained in this area and photosynthesis continues to take place, providing the larva with food.  The leaf-mining larva (Ectoedemia sp.) will pupate over the winter (outside the leaf) and emerge next spring as a very tiny moth which will feed on the honeydew secreted by aphids. (Photo: Mined Bigtooth Aspen, Populus grandidentata, leaf)

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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.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.