Tree of the Week

Boxelder, Acer negundo L.

DISTINGUISHING CHARACTERISTICS: Leaves once-pinnately compound, opposite; leaflets 3 to 9 in number (usually 3 or 5), ovate, sometimes shallowly lobed, 2 to 4 inches long, the margins entire or coarsely and shallowly toothed. Winter twigs moderate in diameter, green or purple, usually coated with a white waxy substance; leaf scars V-shaped with 3 bundle scars, opposing leaf scars joined at their ends and thus encircling the twigs, the junction prolonged upward into a short point on each side of the twig. Buds ovoid, densely white-hairy, 1/8 to 1/4 inch long with 2 or 4 visible scales. Flowers very small, greenish, dioecious, apetalous, appearing just before the leaves  in spring; staminate long-stalked in umbellike clusters; pistillate in racemes. Fruit a pair of samaras joined at the base; wings 1 to 2 inches long, drooping; samaras ripening in autumn, often remaining on the tree through winter. Bark gray or brown, furrowed with scaly ridges.

SIMILAR TREES: Ashes, the only other common trees with opposite, pinnately compound leaves, have 7 to 11 leaflets and single, paddle-shaped samaras. Easily distinguished from other maples and ashes in winter by its greenish or purple twigs, white-hairy buds, and upward-poiting leaf scar junctions.

IOWA DISTRIBUTION: Native throughout the state, occasionally cultivated.

Forest and Shade Trees of Iowa (Third Edition), by Peter J. van der Linden and Donald R. Farrar

Gardening in October

Tuesday, October 3

On a crisp, clear morning like this, I sometimes wish I could stay home forever. Just sitting on the back steps, taking it all in. The grass spangled with yellow walnut leaves. The yard framed with golden walnut trees .A shaft of sunlight angling through the open branches, suffusing the air and a piece of the big vegetable bed with its luminous beam. Yellow and green, yellow and green. With a few spots of pale brown among the pin oak leaves, and several specks of purple and pink among the pear leaves, and a few hints of orange amid the maple. So striking a leafscape, a landscape, I was momentarily transfixed by it.

Carl H. Klaus, My Vegetable Love: A Journal of a Growing Season

Butterfly of the Week

Silver-spotted Skipper

Epargyreus clarus (Cramer [1775])
Status: Common breeding resident
Flight: Multiple brooded, flying throughout the growing season. It is most often encountered from late May to mid July.
Distinguishing features: The Silver-spotted Skipper's large size, dark brown color, medial gold band on the upper and lower fore wing, and large silver band on the lower hind wing make it easy to identify. Wingspan: 4.5-5.5 cm.
Distribution and habitat: Map 5. Found throughout the state in a wide variety of wooded habitats. It was first reported in Iowa from Denison in Crawford County in 1869.
Natural history: The Silver-spotted Skipper is an extremely strong flyer. It is very pugnacious and will even dart at small birds. While Paul Opler and George Krizek (1984) report that its larvae consume a large variety of common woodland legumes, no favored host plants have been recorded in Iowa. It is likely that it eats a large variety of common woodland legumes, such as black locust, honey locust, hog peanut, and tick-trefoil.
Questions: Is the pugnacious behavior of perching adults toward flying intruders part of the courtship pattern pr a form of territoriality? What is the selective advantage of the large silvery-white spot on the vertical hind wing?

The Butterflies of Iowa, by Dennis W. Schlicht, John C. Downey, and Jeffrey C. Nekola