By Kathy Van Mullekom
An alternative to the aggressive-growing Chinese and Japanese wisterias, American Wisteria, or Wisteria frutescens, grows slowly, and is easy to control with pruning.
“Its branches twine freely up tree trunks and trellises, and hanging masses of beautiful purplish-white flower clusters cover the plant in spring,” according to Helen Hamilton, past president and author of “Wildflowers and Grasses of Virginia’s Coastal Plain.”
The blossoms of the native and introduced species are similar but those of the native vine have no fragrance. Further, the flowers on the native vine bloom after the leaves appear, while the flowers on the Asian vines appear before the leaves. The native species blooms April-May, while the Chinese and Japanese species bloom April-July.
The wisterias are high-climbing vines with feather-compound toothless leaves – only subtle differences distinguish the native from the introduced species. Fruits are brown, bean-like pods that persist until winter; the native wisteria fruits are smooth while the Asian species produce velvety pods.
“American Wisteria is not aggressive, and is well-suited for garden plantings, on a trellis or along a deck railing,” Hamilton said.
This vine prefers moist or wet woods and riverbanks, and occurs occasionally in roadsides and fencerows. The plant grows throughout the eastern United States, but is found in the wild in only a few counties in southeastern Virginia.
“The Chinese and Japanese wisterias are very difficult to control when established, reproducing by seeds and by forming roots at the nodes,” said Hamilton.
“When cut back or trimmed, new shoots will be produced. These non-native species are highly aggressive, growing up shrubs and trees, eventually shading and killing native plants.”
Many cultivars are available in the nursery trade. But the straight species is a larval host for the long-winged skipper butterfly, and is pollinated by carpenter bees. Cultivars may not be attractive to pollinators, and may not produce copious blossoms. And cultivars do not host native butterflies.
The name suggests the activity of these bees – the eastern carpenter bee, or Xylocopa virginica, which use their large mandibles to scrape tunnels into wood, excavating a cavity that grows over an inch long per week, according to Hamilton. The opening is circular, about half-inch wide, and when complete the average tunnel is 5-7 inches long. This is where the female will lay eggs and store food, a ball of pollen and nectar to feed the emerging larva. Each female produces six to nine eggs, which develop in individual cells in the tunnel.
The adults visit a great variety of flowers in gardens as well as natural habitats. Eastern carpenter bees are important pollinators for some plants – American wisteria (Wisteria frutescens), passionflower vine (Passiflora incarnata), and, like bumblebees, they are effective “buzz pollinators” of tomato, eggplant and other crops.
Carpenter bees are large, about an inch long and resemble queen bumblebees, but their abdomen is glossy, not hairy, and black but without yellow bands. Males have a conspicuous white spot on their face which is lacking in females. Females are docile, but can sting when aroused. The males are aggressive, defending territory and mates, but cannot sting.
“These insects build their nests in wood siding, the ends of logs used in modern log houses, the back face of the trim under eaves where the surface is not painted, or other areas where bare or painted wood is exposed,” Hamilton said.
“Unfortunately for homeowners, the tunnel excavating process produces yellow sawdust containing waste materials which leaves unsightly stains on the wood. Since the tunnels are small, structural damage only occurs after many years when the bees bore new holes or enlarge tunnels in the same location. Occasionally the carpenter bee larvae attract predatory woodpeckers that extend the damage caused by the adults.”
In the east, eastern carpenter bees occur almost anywhere – from coastal southern Maine west through southern New England, New York, and extreme southern Ontario to eastern Iowa south to eastern Texas and nearly all of Florida. They are most conspicuous when they form nesting colonies in the exteriors of houses, barns, other out buildings and fence posts, but they are also common in forests where they nest high in dead trees or large dead limbs on living trees, Hamilton said. They may prefer to nest in pines and other conifers, but they are not restricted to them. They tend to nest in dry wood in sunny places.
Kathy Van Mullekom is the garden/home columnist for the Daily Press in Newport News, Va. Follow her on FacebookKathy Hogan Van Mullekom, on Twitter diggindirt and at Pinterestdigginin. Her blog can be read at DigginRoomandYard.com. Email her at kvanmullekomaol.com.
©2014 Daily Press (Newport News, Va.)
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