Herbs, annual, rarely overwintering, to 1.4 m; roots not rhizomelike. Stems erect. Leaves 2.5–11 cm; petiole (2–)2.5–9 mm; extrafloral nectary 1(–3), sessile or shortly stipitate; leaflets (7 or)8–22(–26) pairs, blades linear-oblong, oblong, oblong-oblanceolate, or -elliptic, apex mucronulate to subacute, (5.5–)7–20(–23) × (1.3–)1.5–5(–6) mm. Racemes 1–4(or 6)-flowered, supra-axillary. Pedicels (6–)8–22(–26) mm; bracteoles distal to mid pedicel. Flowers: calyx greenish, sepal venation reticulate; corolla yellow, fading brown or orange, rarely whitish, 2–4 petals with reddish maculate at claw, to 10–23 mm; stamens 10; anthers all or some yellow, yellow and red-tipped, red, red-brown, or red-violet, to (5.5–)6–10.5 mm; ovary often hairy, sometimes glabrous. Legumes straight or curved, linear-oblong, (3–)3.5–6.5(–10) × (25–)30–75(–85) mm. Seeds (2.8–)3.2–4.8(–6.3) mm. 2n = 16.

Phenology: Flowering mid spring–early fall(–winter).
Habitat: Open woods, fields, roadsides, inland and coastal dunes, coastal prairies, disturbed hardwood prairies, tallgrass prairies, sandy patches in shortgrass prairies, pine-savannas, usually in dry, sandy soils.
Elevation: 0–1400 m.

Distribution

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Ont., Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.J., N.Mex., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., S.Dak., Tenn., Tex., Vt., Va., W.Va., Wis.

Discussion

Due to its high morphological variation, Chamaecrista fasciculata has been characterized by a history of shifting species and infraspecific taxonomic boundaries. Even its current definition is not satisfactory (H. S. Irwin and R. C. Barneby 1982), especially considering the high similarity (and probably very close relationship) with other partially sympatric species of Chamaecrista, such as C. chamaecristoides, which occurs in Texas, and C. deeringiana in the southeastern United States. Chamaecrista fasciculata also closely resembles C. nictitans but can be distinguished by its ovoid-acuminate floral buds, which are globose-ovoid in C. nictitans. Chamaecrista fasciculata is the first non-papilionoid legume to become a model species in genomics (S. R. Singer et al. 2009). It has been used to address research questions ranging from climate change (J. R. Etterson 2004) to specialized pollination biology (C. B. Fenster 1995) and ant-plant interactions (M. T. Rutter and M. D. Rauser 2004; R. S. Rios et al. 2008).

Cassia chamaecrista Linnaeus is a rejected name that pertains here.

Selected References

None.

Lower Taxa

None.