Bean family (Fabaceae)
Description: This perennial wildflower is about 1-2' tall, branching occasionally to frequently. It is ascending to erect, although some of the side branches may sprawl across the ground in open areas. The central stem and side branches are light green, hairless, and terete or angular in cross-section. The alternate compound leaves are odd-pinnate with 5-15 pairs of leaflets and a terminal leaflet; the compound leaves are up to 3" long and they have short petioles. Individual leaflets are 3/8" long and 1/8" across; they are medium green, oblong, hairless, and smooth along their margins. Each leaflet has a very short petiole and a tiny pointed tip. Upper stems terminate in individual spikes of flowers that are short and cylindrical in shape; individual flowers and their bracts are densely crowded together along the length of each spike in all directions. The petals of these flowers are medium purple or rose-pink (rarely white), while their sepals and bracts are green-white. Each flower has 5 petals, 5 sepals, 5 stamens, and a pistil with a single style. The petals are oblanceolate or obovate and longer than the sepals. The short sepals are lanceolate with green tips and white bases. Underneath each flower, there is a lanceolate bract with an elongated tip that is awn-like. The exerted stamens have white or pale purple filaments and orange to brown stamens. The blooming period occurs from mid- to late summer and lasts about 1-2 months. There is no noticeable floral scent. Each flower is replaced by a short seedpod with a slender beak that is largely enclosed by the persistent sepals; each seedpod contains 1-2 smooth seeds. As the seeds mature, the floral spikes become dark brown. The root system consists of a short stout taproot with fibrous rootlets. This wildflower reproduces by reseeding itself. Individual plants typically live less than 8 years.
Cultivation: The preference is full or partial sunlight (at least one-half day of sunlight), moist to slightly dry conditions, and a thin rocky soil. The pH of the soil should lie within the range 6.0–8.0; strongly acidic soil should be avoided. This wildflower will adapt to ordinary clay-loam garden soil if its location is sunny and well-drained; however, it is intolerant of competition from taller and more aggressive plants.
Range & Habitat: Leafy Prairie Clover has been observed in only a few counties in northern Illinois (see Distribution Map). Today, it is restricted to 2-3 small colonies in Will County; the populations of the remaining colonies have been extirpated by development or over-collection. Leafy Prairie Clover also occurs in Tennessee and Alabama. Populations have declined in all three states. This native plant is quite rare and it is listed as 'endangered' by both the state of Illinois and the Federal government. In Illinois, habitats are restricted to mesic dolomite prairies and rocky riverbanks. In Tennessee and Alabama, habitats are restricted to cedar glades and meadows along the edges of cedar glades.
Faunal Associations: Floral visitors of Leafy Prairie Clover are probably similar to the floral visitors of Dalea purpurea (Purple Prairie Clover); the insect visitors of the latter include many kinds of bees (short-tongued & long-tongued), butterflies, flies, and occasional wasps. These insects are attracted to the nectar and/or pollen of the flowers. The caterpillars of the butterfly Colias cesonia (Dogface Sulfur) feeds on the foliage of Dalea spp. (Prairie Clovers) and other species in the Bean family. Other insects that feed on Prairie Clovers include Apion amaurum (Weevil sp.), Apion capitone (Weevil sp.), and Pachybrachis othonus (Cylindrical Leaf Beetle sp.); none of these records are specific to Leafy Prairie Clover, however. The foliage of Leafy Prairie Clover is highly palatable to mammalian herbivores, including deer, rabbits, groundhogs, cattle, horses, and others. In Illinois, rabbits have been a major cause of plant mortality for this species. This rare wildflower should be protected from such animals where their populations are excessive.
Photographic Location: The wildflower garden of the webmaster in Urbana, Illinois; the photographed plant was obtained from a specialist nursery using horticultural sources, rather than wild-collected material.
Comments: Unfortunately, this attractive wildflower is approaching extinction in natural areas. Compared to other Dalea spp. (Prairie Clovers), it has a more leafy appearance. Leafy Prairie Clover can be distinguished from other Prairie Clovers in Illinois by the number of leaflets per compound leaf (typically 21-25, although there can be fewer or more leaflets than this). Both Dalea purpurea (Purple Prairie Clover) and Dalea candida (White Prairie Clover) have fewer leaflets per compound leaf (less than 10). As it common name suggests, White Prairie Clover has flowers with white petals. The floral bracts of Purple Prairie Clover are shorter than those of Leafy Prairie as they lack the awn-like tips of the latter. A species that is found in neighboring states (although not Illinois), Dalea villosa (Silky Prairie Clover) has abundant leaflets, but its foliage is covered with abundant silky hairs. In contrast, Leafy Prairie Clover has hairless foliage.