Wildflower of the Year (2005)

 
The following is excerpted from Growing Native Wildflowers by Harder and Platt.

94.15 ROSE VERVAIN or ROSE VERBENA (Verbena canadensis)
 


DERIVATION OF NAMES. "Rose" refers to the bright rose-purple color of the flowers; "vervain" comes from an old French name for this group of plants; "Verbena" (from Latin) - a classical name for the branches of trees used in religious rites; "canadensis" - Canadian, a name like this usually refers to the locality of collection of the plant used in the original description of the species. (Rose vervain does not grow naturally in the country of Canada.) Barr (1983) states that it was named for the Canadian River in the southern Plains. But Linnaeus, 18th century botanist and describer of this species, used Canada to refer to a large region in northeastern North America, partly in Canada, but mostly in what is now the United States).

OTHER COMMON NAMES. Large-flowered verbena, clump verbena.

OTHER SCIENTIFIC NAMES (SYNONYMS). Verbena drummondii, Glandularia canadensis.
 


flowering heads (x 0.5)


RELATIONS. Vervain family (Verbenaceae). Rose vervain can be recognized as a vervain by the oppositely arranged leaves, the flower structure - the petals fused into a 5-lobed corolla tube and 5 stamens - and the fruits, 4 small nutlets from each flower. Verbena is a large genus found principally in tropical and temperate America.

ORNAMENTAL CHARACTERISTICS. Stevens (1961) wrote many years ago, "Though this species has contributed to the production of popular garden hybrids, we esteem its uncontaminated self, in its wild estate, above any kinds pampered in the garden." The ease with which it can be grown and the long blooming season are characteristics that recommend this plant. It can be grown easily as a ground cover among other taller plants or in a rock garden; or it can be used to add color to a lawn or garden through much of the summer. The somewhat hairy stems are multi-branched. They are usually prostrate, creeping over the ground and often rooting at the lower nodes, but turned up at the end. Occasionally upright stems make the plant appear bushy. The stems are usually square in cross-section and often tinged with red. Although these stems may be 1 to 2 1/2 feet in length, the plant itself is rarely more than 1 foot tall. The leaves are deeply dissected into 3 main divisions but each of these is incised into irregular small lobes or teeth. The dark green leaves are somewhat hairy at least along the margins. Flowering begins in early May and may continue throughout the summer and into the fall if moisture is sufficient. The flowers are produced in showy clusters at the end of each stem and branch. The clusters are at first broad and flat, but later elongate into thick flowering and fruiting spikes. New flowers continue to be formed at the tip of the stem while the old flowers below form fruits hidden in hairy green bracts and calyxes. Each pink to rose-purple flower is approximately 1/2 inch across. It has a corolla tube with 5 spreading lobes at its apex, each lobe notched at its tip. The flowers may be cut to use in fresh bouquets but they are not long-lasting.

GROWTH CHARACTERISTICS AND MANAGEMENT. Rose vervain is a short-lived perennial, often dying after 2 or 3 years. A number of stems may come out of one crown but each stem may also be rooted at some of its nodes. The leaves have an opposite arrangment on the stem. If moisture is sufficient, the plant will remain green all summer, and some of the lower leaves and stems may remain green over winter if they have some protection. The roots are fibrous and rather shallow. Although the plant spreads by the rooting of its prostrate stems, it is easy to control. If it is started from seed in the spring it may bloom later the same year.

RELATIONS TO ANIMALS. Eddy (1992) found that rose vervain was not affected by cattle grazing as he found similar numbers of plants in grazed pastures and along ungrazed roadsides in the Flint Hills of Kansas.

Rose vervain attracts many insect pollinators. We have observed black swallowtail (Papilio polyxenes) and painted lady (Vanessa cardui) butterflies, small sphinx moths and syrphid flies visiting rose vervain flowers.

SEEDS AND FRUIT. The fruit is a grayish-black to black one-seeded hard nutlet. The surface is covered with small ridges and papillae. Four nutlets develop inside the persistent calyx of each flower. Seeds can be collected when the calyxes containing the nutlets turn light brown and dry, 6 to 8 weeks after blooming has started. After removing the small calyxes from the seed spike, nutlets can be picked out easily. The nutlets should be dark and hard.


seed spike (x 0.8)

 


individual nutlet (x 11)


SEED GERMINATION. In an experiment by Baskin and Baskin (1988), seeds harvested and planted in the summer under outside conditions had their peak germination the next spring, although some seeds did not germinate until the second and third year. We have experienced 15% germination after 8 weeks of moist stratification, an average 59% after 11 weeks, and 71 % after 13 weeks (4 lots totaling 98 seeds). Germination occurred within 12 days following removal from the cold.

GROWING SEEDLINGS. Untreated seed can be planted in the field in fall or treated seed can be planted in spring. Treated seed can also be started indoors in flat" or pots in spring. Seed should be planted 1/4 inch deep. Seedlings establish easily in the greenhouse and have few problems. Those started indoors can be transplanted into the field when they are 8 to 12 weeks old.

The pair of small dark green ovate cotyledons emerge on short stalks. The first true leaves that appear are elliptical, slightly hairy, and with finely toothed edges.

VEGETATIVE REPRODUCTION. Rose vervain can be transplanted successfully even when in full bloom (Stevens 1961). However it is best to divide it in the spring when each small piece of stem with roots can produce a new plant. Stem cuttings can also be taken in the summer and root easily (Taylor and Hambin 1963; Wilson 1992). Taylor and Hamblin (19_3) also mention, concerning rose vervain, that "...in good soil it usually dies in a few years. It may be carried on indefinitely, however, by starting new plants from the self-rooting stems."

GEOGRAPHIC RANGE. Rose vervain grows naturally in the eastern 1/3 of Kansas. Its range extends from North Carolina and Kentucky west to Iowa and southeastern Nebraska and south to Florida and eastern Texas.

HABITAT. Rose vervain is found in open prairies, particularly on rocky hillsides. It is also found in pastures, along roadsides and in open woods. Wilson (1992) says it can be planted in sandy or rocky soil in full sun or light shade, particularly afternoon shade.

Copyright © 1994 Kansas Native Plant Society

 

For more information and photographs: http://www.lib.ksu.edu/wildflower/roseverbena.html