2012 Kansas Wildflower of the Year
LEAD PLANT Amorpha canescens
DERIVATION OF NAMES
"Lead plant" - from the gray leaden color of the foliage; "Amorpha" (from Greek) no form or deformed, because the flowers are much simpler than typical legume flowers; "canescens" (from Latin) becoming gray.
OTHER COMMON NAMES
Lead-plant amorpha, downy amorpha, prairie shoestring, devil's shoestring, wild tea, tea plant, false greasewood.
SCIENTIFIC NAMES (SYNONYMS)
Bean or legume family (Fabaceae). This species can be recognized as a legume by the compound leaves and typical fruits (legumes). The corolla of the flower is simplified but other flower structures are typical of this family. There are 20 species of the genus Amorpha, all North American.
The grayish green velvety foliage and the orange-dotted purple flower wands of lead plant are a pleasing addition to an ornamental planting. It grows 2 to 3 1/2 feet tall or even taller if it is allowed to become shrubby. The leaves are pinnately compound with an odd number of leaflets (27-41). The leaflets become smaller, more densely placed and partially overlapping toward the tip of the leaf. The short dense covering of hairs on the leaves and stem produce a grayish cast to the plant. Lead plant blooms from June to late July or early August. The small flowers are packed in dense spike-like racemes, each inflorescence 2 to 6 inches long, at the tips of stems and from the upper leaf axils. The single small petal is purple, above which are protruding orange stamens. The flowers at the bottom of the raceme are the first to open. Each raceme blooms for a few weeks as new flowers continue to open. The "spikes" can be cut and dried as soon as the pods form. They add an unusual purple-gray color to dried plant arrangements.
GROWING CHARACTERISTICS AND MANAGEMENT
Lead plant is a drought resistant perennial, with one to several stems growing from a woody crown. The stems are often branched. If not cut, the plant becomes a shrub with woody perennial stems up to 1/2 inch thick. If grazed, mowed or burned, it grows anew from the crown each year, but even these annual stems become somewhat woody by midsummer. Art (1991) reported that burning stimulated increased growth and flowering of leadplant in a grassland. The leaves are alternately arranged, projecting from all sides of the stem. The annual stems are leafy to the base, but the lower leaves may drop by midsummer, especially if they are shaded. The roots are branched, 6 1/2 to 16 1/2 feet deep, and absorb mainly from below a 3 foot depth. Some shallow roots spread out horizontally from the plant. The breaking of these roots as settlers plowed the prairie sounded like shoestrings snapping and is the basis for two of the common names of this plant (Weaver and Fitzpatrick 1934). Although it is reported to have underground stems (rhizomes), it does not spread aggressively either vegetatively or by seed. Young plants started from seed in the spring do not bloom before the second season.
The Lakota Indians used the dried leaves of lead plant to make a tea (Kindscher 1987). They also used dried leaves mixed with buffalo fat as a smoking material. Preparations from this plant have been used in treatments for cuts and open wounds, intestinal worms and eczema. Small stems of lead plant were used by the Omaha Indians as a moxa for rheumatism. Small pieces of stem were stuck to the skin over the rheumatic area and burned as a counterirritant (Kindscher 1992). A chartreuse dye can be prepared from the flowers and leaves of lead plant using chrome or alum as a mordant (Marilyn Jones, person. comm.). Bacterial nodules occur along the entire length of the roots of this plant and these bacteria are important in the maintenance of nitrogen fertility of prairie soils (Kindscher 1987). Smith and Smith (1980) stated that the seeds can be sprouted and eaten like alfalfa sprouts.
RELATIONS TO ANIMALS
Lead plant is a palatable nutritious forage for livestock and many wildlife grazers. Stubbendieck and Conard (1989) reported that it decreased in abundance under heavy grazing and was a good indicator of range condition but Eddy (1992) found it in equal abundance along ungrazed roadsides and in pastures in the Flint Hills of Kansas. It may survive under moderate grazing. The Lakota Indians called this plant by a name meaning "the bird's tree" because birds use it as a perch in prairies where there are no trees (Kindscher 1987). Caterpillars of the dogface butterfly Zerene cesonia have been reported to feed on this plant (Scott 1986).
SEEDS AND FRUIT
The fruit of lead plant is a small hairy pod with brown glandular spots. Each pod contains a single seed. The pod is approximately 3/16 inch long. The smooth greenish or brownish seeds are approximately 1/8 inch long with a slight lateral beak on one end. The fruiting spikes should be picked when they are dry in July or August. Seeds can be removed from the pods by rubbing the pods over fine sandpaper or a fine sieve. Many pods will not have developed seeds. The seeds can be separated from the chaff by sieving through different mesh sizes or by picking out seeds with tweezers.
Germination is poor without mechanical scarification of the seed. With scarification using fine sandpaper, we have obtained an average germination of 41 % (15- 76% in 8 lots totaling 438' seeds). We have not tried stratification. Smith and Smith (1980) recommended (in addition to scarification) moist stratification for 10 days or soaking seed in hot water (180" F) until it cools. Art (1991) recommended 10 weeks of moist stratification. He reported that the optimum soil temperature for germination is 65-70° F.
Seed should be inoculated with the proper Rhizobium strain if it is to be grown in soil that has not had lead plant growing in it recently. Art (1991) warned against using nitrogen fertilizer on the young plant as it slows the establishment of the Rhizobium bacteria. Scarified seed can be planted in the field in spring. The seed should be planted 1/4 inch deep. Seedlings are tolerant of shade but grow slowly when competition is high (Weaver and Fitzpatrick 1934). Seedlings can be started indoors in pots or started in flats and transferred to pots after the seedlings have two true leaves.
The seedlings grow well in the greenhouse but are slow growing and subject to damping off. The seedling has a pair of small cotyledons which are rounded on the ends and oblong, almost twice as long as wide. The true leaves arise one at a time ~ an upright stem. The first true leaves are simple, round and about as long as wide. The succeeding leaves are larger and later leaves are compound with three leaflets (beginning with the ninth leaf or later). The leaves and stem of the seedlings are smooth without the hairiness and gray color of the mature plant.
Rock (1972) suggested propagating lead plant by suckers, layering during the summer, green wood cuttings early in the season or hard wood cuttings. Art (1991) stated that green wood cuttings of young stems were successful.
Lead plant is found in the eastern 3/4 of Kansas, although it becomes uncommon to the west. It is found through much of the Great Plains, north to southern Manitoba, east to Illinois and Indiana, south to Texas and New Mexico and west to western Nebraska and Kansas.
Lead plant is common in prairies and open woodlands. It is found in sunny habitats and can only tolerate light shade. It needs well- drained soils. Schramm (1992) listed lead plant as typical of later stages in prairie restoration succession. Weaver and Fitzpatrick (1934) found lead plant in 93% of the upland tallgrass prairies they studied and in 52 % of the lowland prairies. They listed this species as "perhaps the most conspicuous and characteristic subdominant of upland tall-grass prairie."
Growing Native Wildflowers by Harder and Platt. page 92.1
See also an article in the Winter 2012 newsletter.