Plant of the Week
Tall Goldenrod (Solidago altissima L.)
By David Taylor
Tall goldenrod is a member of the Asteraceae, the Sunflower family. In older manuals and guides, this family is called the Compositae because the 'flowers' are a composite of many flowers, often of different types. The many species of plants in this family are grouped based on the arrangement and type of flowers. All members of the family produce one or more heads (capitulum, the term used in technical keys) of flowers. This and other goldenrods have two different types of flowers, ray flowers and disk flowers and in turn, these can have male and female parts, or either one or the other. The ray flowers look like petals, but each is actually an individual flower. The disk flowers are at the center of the head, inside the ring of ray flowers. The disk flowers are usually small. With a hand lens one can see the distinct tips of five petals in each flower. The disk flowers closest to the ray flowers open first.
This goldenrod is 0.5–2.0 meters (1.6–6.6 feet) tall, and is among the tallest of goldenrods, hence its common name. The stem is rigid and generally smooth. Leaves are alternate and are 6.4–8.9 centimeters (2.5–3.5 inches) long by 1–2 centimeters (0.4–0.8 inches) wide. The underside of the leaves is covered in thin stiff hairs. Heads are generally borne individually or in clusters of two or three, and are found at the top of the plant. Each head generally has five ray flowers that are 2–3 millimeters (0.08–0.12 inches) long, and numerous disk flowers. Both the ray and disk flowers are yellow. The entire head is 7–8 millimeters wide (0.28–0.31 inches) wide. Tall goldenrod often forms galls mid-stem, and sometimes rosette producing galls at the top of stems in response to stem-boring insects.
Tall goldenrod is an open land species generally found on drier soils. It is a species of prairies and other grasslands, old fields, roadsides, savannas and woodlands, also occurring in forest openings. It is found across the United States with the exception of Washington, Oregon, Idaho, Nevada, Utah, and Wyoming. It is also known in Canada from Saskatchewan east to New Brunswick and Prince Edward Island, and in Mexico.
This species flowers in August to November depending on the part of the country in which it is found. It is a strong competitor in part to alleleopathic compounds (chemicals that suppress the growth of other plants) it produces and in the garden and grasslands, it can become weedy. Introduced to Europe and Asia, it has become a serious weed in those locales. Bees, wasps, butterflies, and beetles, especially flower (soldier) beetles (genus Chauliognathus) are strongly attracted to the flowers- see photo. Tall goldenrod is often called Solidago canadensis L. var. scabra Torr. & A. Gray in older manuals.
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