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Roadside weed ID

July 28, 2009

The roadsides are a rainbow of color right now - yellows, whites, pinks, and purples. With flowers in bloom, mid-summer is a good time to identify plants you might see along your daily commute.

One of the most prominent roadside plants is white sweet clover (Melilotus alba). It grows to heights of 3 to 5 feet, has multiple branching stems, numerous stalks of densely packed white flowers and greyish green foliage.

Chicory (Cichorium intybus) might catch your eye with its bright, bluish-purple, radial flowers. Reaching 3 feet, its stems are wiry and its leaves are somewhat angularly arranged. Did you know that chicory is best known for being associated with coffee? Its long, thick root can be roasted as a coffee substitute, though without the caffeine (and preferably not from plants growing along roadsides).

Article Photos

Bird’s foot trefoil

Another purple flowering plant, though less conspicuous, cow vetch (Vicia cracca) grows closer to the ground with trailing or climbing stems. Its leaves have 8-12 pairs of narrow, oval-shaped, opposite leaflets. Tendrils, common to the pea family, securely fasten to other plants and form sprawling mats.

Crownvetch (Coronilla varia) is also a member of the pea family but is not a true vetch. It is a bushy, low growing vine with 5 to 20 pink, pea-like flowers clustered at the end of extended stalks. It spreads from rhizomes and forms a dense cover. Erosion control was the intended goal of its planting in the 1950s, but crownvetch has since become a problem, invading fields and pastures.

Many showy, yellow flowers brighten the roadside too. One of them is bird's foot trefoil (Lotus corniculatus), growing to heights of 1 to 2 feet and named because its pea-like flowers grow at right angles to the flower stalk, resembling a bird's foot.

These are some of the many introduced plants splashing color along roadway corridors at this time of year. Though many people think these plants are native, most are European transplants introduced in the 1600s or 1700s for aesthetic, medicinal or herbal purposes.

As opportunists, these plants are the first to colonize disturbed areas, like roadsides. Also found in vacant lots and waste areas, they thrive in full sun, slightly moist to dry conditions and gravelly, sandy soils.

Unlike invasive species, these non-natives often do not expand from the roadsides and are not as problematic in the Adirondacks. Nevertheless, intentionally spreading them is not recommended. In other parts of the state and country, they invade fields, meadows and disturbed open areas.

A greater thrill is viewing the native plant assemblage. Keep eyes open for milkweed's cluster of pinkish white flowers (its leaves are an important food source for larval monarch butterflies), the airy pinkish-purple spike of fireweed (not to be confused with the invasive purple loosestrife) and various golden-yellow sprays of goldenrods.

Although tempting, never transplant roadside plants to gardens. Avoid picking roadside flowers too, and be mindful if buying bouquets at roadside stands that they do not include invasive plants, which can be spread if carelessly discarded. Also, remember to read labels of wildflower seed packets, which may contain these and other weed-seeds.

'Eye on Invasives' is a biweekly column that spotlights a top invader when it is easiest to identify. The Adirondack Park Invasive Plant Program is a partnership program housed at the Adirondack Chapter of The Nature Conservancy in Keene Valley. Find out more about this award-winning program online at



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