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dark indigo-bush, shining false indigo

bastard indigo, bastard indigobush, bastard or desert false indigo, desert false indigo, false indigo-bush, tall indigo bush, western false indigo

Habit Shrubs, 1–2(–3) m; arising from compact, woody root. Shrubs, (1–)2–3(–4) m; arising from compact, woody root.
Stems

smooth, usually eglandular, mostly glabrous or puberulent.

smooth, eglandular or, sometimes, sparsely gland-dotted, usually puberulent to glabrate, rarely glabrous.

Leaves

10–18(–22) cm;

stipules linear to narrowly setaceous, 3–5 mm, sometimes sparsely gland-dotted, short-pilose;

petiole (15–)20–35(–50) mm, eglandular, usually glabrous;

rachis eglandular, usually glabrous;

leaflets (7–)9–15(–19), stipels not seen, petiolule 2–5(–7) mm, eglandular, glabrous or pilosulous, blade drying blackish, usually elliptic to oblong, sometimes ovate, 20–40(–70) × (10–)15–35(–45) mm, base round, margins flat, entire, apex usually emarginate, sometimes round, surfaces distinctly shiny adaxially, usually glabrous and eglandular, rarely sparsely puberulent and sparsely gland-dotted abaxially;

midvein terminated by a slender mucro, 0.1–0.2 mm.

10–25(–28) cm;

stipules linear, 2–4 mm, usually eglandular, pilosulous;

petiole (8–)10–40 mm, usually eglandular, sometimes sparsely gland-dotted, usually puberulent to glabrate, rarely glabrous;

rachis usually eglandular, sometimes sparsely gland-dotted, puberulent to glabrate;

leaflets [5–]9–21(–31), stipels setaceous, 2–4 mm, petiolule (1.5–)2–4 mm, often eglandular, sometimes sparsely gland-dotted, usually pilosulous to puberulent or glabrate, rarely glabrous, blade usually elliptic to oblong, rarely ovate, (10–)20–40(–50) × (5–)10–20(–25) mm, base acute to rounded, margins flat, entire or nearly so, apex acute to round or, rarely, emarginate, surfaces usually pilosulous to puberulent or glabrate, sometimes glabrous at least adaxially;

midvein terminated by a slender mucro, 0.5–1.5 mm.

Racemes

1–3(–8)-branched, (5–)8–15(–25) cm;

rachis usually eglandular, usually glabrous, sometimes puberulent;

bracteoles drying blackish, linear to setaceous, 1.5–3(–4) mm, usually eglandular, glabrous or short-pilose.

(1 or)2–8(–12)-branched, (5–)10–20(–25) cm;

rachis usually eglandular, mostly puberulent to pilosulous, sometimes glabrate;

bracteoles linear to setaceous, 1.5–3 mm, pilosulous abaxially, glabrous adaxially.

Pedicels

drying blackish, 1–2.2 mm, eglandular, glabrous or short-pilose.

1–2.2 mm, usually eglandular, puberulent to pilosulous.

Flowers

calyx drying blackish, tube usually funnelform to obconic, rarely campanulate, 2–2.5 mm, usually eglandular, glabrous or short-pilose;

lobes: abaxial lobe triangular, slightly longer, adaxial lobes round to triangular, 0.2–1.4 mm;

banner reddish purple, broadly obovate, 4.5–6 × 3–4.8 mm, obscurely clawed, margins entire or irregularly erose;

filaments 5–7 mm, connate basally 2–2.5 mm;

anthers yellow;

ovary glabrous.

calyx tube obconic to funnelform or campanulate, 2–3(–4) mm, distal 1/3 gland-dotted or, infrequently, eglandular, puberulent to pilosulous or glabrous;

lobes triangular-dentate, 0.2–1.2 mm, margins ciliate;

banner reddish purple, broadly obovate to obcordate, 5–6 × 3.5–4.2 mm, indistinctly clawed, margins entire, apex slightly emarginate or erose;

filaments 6–8 mm, connate basally 1–2(–3) mm;

anthers yellow;

ovary glabrous or, rarely, pubescent.

Legumes

short-stipitate, 6–8 × 2.5–3.5 mm, margins curved outward abaxially, straight or slightly curved inward adaxially, rarely at least distal 1/3 gland-dotted, glabrous.

sessile, 5–9 × (2–)3–4.5 mm, margins curved outward abaxially, straight to curved adaxially, more often gland-dotted nearly throughout, sometimes eglandular, usually glabrous or pubescent.

Seeds

not seen.

reddish brown, 3.5–4.5 × 1.5–1.8 mm, smooth, lustrous.

2n

= (38) 40.

Amorpha nitens

Amorpha fruticosa

Phenology Flowering Apr–Jun. Flowering Apr–Jun(–Jul).
Habitat Moist thickets and woods. Dry or moist grasslands, scrublands, woodlands, river and stream banks, tidal marshes, roadsides, fields, or waste places.
Elevation 50–600 m. (200–2000 ft.) 0–2400 m. (0–7900 ft.)
Distribution
from FNA
AL; AR; GA; IL; KY; LA; OK; SC; TN
[BONAP county map]
from FNA
AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MD; ME; MN; MO; MS; NC; ND; NE; NH; NJ; NM; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; MB; NB; ON; QC; Mass Mich; Mexico (Baja California, Chihuahua) [Introduced in Europe, Asia, Africa]
[WildflowerSearch map]
[BONAP county map]
Discussion

Amorpha nitens is listed as endangered by the state of Illinois and as a species of special concern in Georgia; it is considered to be a sensitive species in the Shawnee National Forest by the United States Forest Service. Amorpha nitens and A. fruticosa share most of their characters and differ most distinctively by the tendency to blacken upon drying ascribed to A. nitens, although some A. fruticosa individuals can blacken upon drying as well.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Amorpha fruticosa is frequently planted as an ornamental and is locally naturalized in Europe, Asia, Africa.

Following R. L. Wilbur (1975) and D. Isely (1998), we maintain Amorpha fruticosa here in a broad circumscription, as the numerous varieties, forms, and regional species delimited from the larger taxon appear to have little taxonomic value due to overlapping morphological variation and widespread plasticity. This species is commonly available in the horticultural trade and is cultivated worldwide. Plants in cultivation can be especially robust, rising to six meters tall with far fewer leaflets than usual. Amorpha fruticosa spreads easily in riparian habitats and is often weedy. Although the native range of A. fruticosa encompasses much of North America, it has only relatively recently become established in the Pacific Northwest, perhaps due to its use for erosion control, and has only been recorded from Idaho, Oregon, and Washington since the 1980s (J. B. Glad and R. R. Halse 1993). This species is considered to be introduced also in Ontario and Quebec.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Amorpha Fabaceae > subfam. Faboideae > Amorpha
Sibling taxa
A. californica, A. canescens, A. confusa, A. crenulata, A. fruticosa, A. georgiana, A. glabra, A. herbacea, A. laevigata, A. nana, A. ouachitensis, A. paniculata, A. roemeriana, A. schwerinii
A. californica, A. canescens, A. confusa, A. crenulata, A. georgiana, A. glabra, A. herbacea, A. laevigata, A. nana, A. nitens, A. ouachitensis, A. paniculata, A. roemeriana, A. schwerinii
Synonyms A. angustifolia, A. bushii, A. croceolanata, A. curtisii, A. dewinkeleri, A. fruticosa var. angustifolia, A. fruticosa var. croceolanata, A. fruticosa var. occidentalis, A. occidentalis, A. tennessensis, A. virgata
Name authority F. E. Boynton: Biltmore Bot. Stud. 1: 139. (1902) Linnaeus: Sp. Pl. 2: 713. (1753)
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