Hairy Bush Clover (Lespedeza hirta) of the Pea or Legume (Fabaceae) family is a perennial herb with stems to 3+ feet tall, bearing tightly clustered racemes of small creamy white flowers. The genus name is dedicated to Vicente Manuel de Cespedes (an early botanical text misspelled his name as “de Lespedez”), governor of the Spanish province of East Florida, 1784-1790, during the botanical travels there of Andre Michaux who described the genus. The species name is from the Latin word hirtus for “hairy,” in reference to the plant’s dense pubescence. In the U.S., the species occurs across a large area from eastern Texas and southern Michigan, east to Maine and Florida. In Arkansas, it occurs mostly statewide with the exception for portions of the Mississippi Alluvial Plain. Habitats are sunny to partially sunny areas in sandy to rocky, dry to moist soils, such as open woodlands, prairies, and glades.
Plants produce several to many slender, round stems from a relatively short taproot and wide-spreading lateral roots. Stems average about 3 feet long but may reach 4½ feet. A 4-foot plant may have stems ¼ inch thick near the base. Smaller plants tend to branch only in the inflorescence, while more robust plants may have branches from mid-stem to 16 inches long with secondary branches of several inches. In general, lower branches are shorter than upper branches. Most branches terminate with an inflorescence. Stems are erect but become broadly arched as height increases and with the weight of the inflorescence. Stems and branches are uniformly covered by dense, short, soft, spreading pubescence. Stems are brittle and snap easily.
Compound, trifoliate, alternate leaves are regularly spaced from the base of the stem into the inflorescence. Both lateral and terminal leaflets are ovate to orbicular, green above, pale and yellowish beneath, with apexes and bases equally rounded. Leaves may be as large as 2+ inches long, including a ½-inch petiole, and 2 inches wide. The tip of the leaflets is typically mucronate––bearing a minute spine-like extension of the midrib. Like the stems and branches, the petioles, petiolules (leaflet stalks), rachises, and the undersurface of the leaflets are pubescent with rather softly spreading hairs. Pubescence of the upper leaflet surface is sparser and more appressed. Leaf bases bear a pair of weak greenish spine-like stipules (to ⅛ inch long) which quickly become brown but often remain attached. Venation is pinnate with upper veins weakly recessed and lower veins strongly expressed. Leaflet margins are entire (uncut) and strongly revolute (down-turned). With stem age and drying soils, leaf-drop proceeds upwards from the stem base and may extend into the inflorescence
Bloom time is September into October. The inflorescence comprises short (to ¾ inch), dense racemes of small, short-stalked flowers at the tips of the stems and branches. Racemes that are lower on the plant are subtended by a leaf, while those above are subtended by a pair of tiny broadly triangular bracts. Racemes may be sessile or on straight peduncles to 1½ inches long. They bear up to about 20 flowers. Often, especially at the top of the plant, racemes become densely spaced, terminating the stems in tight clusters of 15± racemes. Drying soil causes some racemes to not develop fully, resulting in naked peduncles during the growing season.
Flowers have a bilaterally symmetrical, pea-like structure typical of the majority of genera in the Legume family: an upright broad banner petal, a pair or elongate wing petals, and a pair of keel petals fused together along their lower margins to form a boat-shaped keel. Wing and keel petals together form a central enclosure that conceals the pistil (ovary + style + stigma) and stamens (filaments + anthers). The corolla is creamy white, the banner with two sets of purplish red “pollinator guides” that radiate from just above the pale green throat and a central crease that extends out of the throat to a slight apical point. The small flowers are ¼ inch long and, when viewed from the front, 3/16 inch tall and ⅛ inch wide. The calyx, 3/16 inch long, has 5 narrow-elongate, sharply pointed, triangular lobes. Calyx lobes, fused at their lower third, are positioned with an upper pair behind the banner, a pair to the sides, and a single lobe directly below the keel. All lobes are pressed against the corolla. The calyx is densely covered with long hairs. Of the 10 slender staminal filaments, 9 are fused in their lower half and tightly encircle the pistil, forming a sort of “column.” The tenth free-standing stamen is positioned between the pistil and banner. Flattened globular anthers, at the apex of the greenish-white filaments, are yellow with a surface that is irregular with intertwined ridges. The ovary bears a short greenish white slender style tipped with a small circular stigma. Towards the distal end of the stamen-pistil column, the column arches upward so that anthers and stigma are positioned just inside a slit at the tip of the keel.
Fertilized flowers produce thin, flat, oval pods or legumes with an extended, sharply tapered beak (remnant of the style). Pods are densely pubescent. With fruit maturity, calyxes and pods become the same rich brown color. Pods extend beyond calyx lobes. Each dry pod contains a single dark brown seed <⅛ inch long with a somewhat flattened oval shape and smoothly rounded edges. Dried calyxes persist into winter.
With regard to gardening, Hairy Bush Clover has an ungainly structure, non-showy leaves and flowers, and is not especially noticeable in winter months. Thus, it may be ideal only for a Wild Garden or Natural Area. Propagating by seed only, it is not an aggressive spreader. Branching can be encouraged by removal of stem tips at mid-season. Foliage is eaten by caterpillars of several Skipper species and the Io Moth. Seeds are eaten by birds and small mammals.
Frost flowers were seen on a dozen Hairy Bush Clover plants on January 3, 2022 in Logan County.
Temperature on that date was 23 degrees after an extended period of 70-degree weather and, two days
before, 3 inches of rain. Occurrence of Frost flowers on Hairy Bush Clover is unusual. One report can be found at the Biodiversity Heritage Library (biodiversitylibrary.org). For information on Frost Flowers, see “Frostweeds ‘Bloom’ Frost Flowers”.
In Arkansas, 7 additional native species and 3 non-native species of bush clovers (Lespedeza) occur. Two of these are ground-hugging trailing plants and most of them have pink to lavender flowers. The one most similar to Hairy Bush Clover is Round Head Bush Clover (Lespedeza capitata). Round Head Bush Clover has similar structure and flower color, but its leaflets are linear-oblong, its inflorescence stalks are shorter than the leaf petioles, and its pubescence usually gives the plant a distinctly silvery appearance.
Article and photographs by ANPS member Sid Vogelpohl