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crenulate false indigo

savanna false indigo or indigo-bush

Habit Shrubs, 0.4–1(–3) m; arising from thick, horizontal rootstock. Shrubs, 0.3–1.4 m; arising from compact, woody root.
Stems

finely longitudinally grooved and ridged, often obscurely gland-dotted, sparsely puberulent or glabrous.

finely longitudinally grooved and ridged, gland-dotted, strigulose to glabrate.

Leaves

(8–)15–25(–30) cm;

stipules mostly acicular, 1.2–2.2 mm;

petiole (3–)8–15(–18) mm, gland-dotted, sparsely puberulent or glabrous;

rachis sparsely gland-dotted, often glabrous;

leaflets (19–)23–33(–41), stipels acicular, 0.4–1.5 mm, petiolule (1–)1.5–2(–3) mm, gland-dotted, usually glabrous, blade elliptic to oblong or ovate to suborbiculate, (7–)12–25(–42) × (2.5–)5–9(–11) mm, base obtuse to round or truncate to subcordate, margins usually conspicuously revolute, crenulate, apex obtuse to round or emarginate, surfaces gland-dotted abaxially, glabrous or glabrate;

midvein terminated by a swollen mucro, 0.2–0.5 mm.

(8–)12–20(–26) cm;

stipules sometimes persistent, linear or setaceous, (1–)1.5–2(–2.5) mm;

petiole (6–)8–15(–20) mm, gland-dotted, puberulent or glabrous;

rachis sparsely gland-dotted, puberulent or glabrous;

leaflets (11–)15–31(–35), stipels acicular or setaceous, 0.8–1.8 mm, petiolule 0.7–1.5(–1.8) mm, gland-dotted, mostly puberulent or glabrous, blade elliptic to oblong or ovate to suborbiculate, (10–)15–25(–35) × (7–)9–15(–18) mm, base truncate or round to subcordate, margins usually revolute, entire or inconspicuously crenulate, apex round to obtuse or emarginate, surfaces sparsely to conspicuously gland-dotted, usually glabrous or glabrate, sometimes sparsely pubescent abaxially;

midvein terminated by a slender mucro, (0.2–)0.4–1 mm.

Racemes

(1–)4–10-branched, (5–)10–25(–30) cm;

rachis sparsely gland-dotted, sparsely puberulent;

bracteoles linear to narrowly spatulate, 1.2–2.5 mm, gland-dotted, sparsely hairy.

(1–)3–5(–8)-branched, 10–20(–30) cm;

rachis sparsely gland-dotted, puberulent;

bracteoles linear to narrowly subulate, 1.5–2.5(–3) mm, usually eglandular, sparsely pubescent or sparsely ciliate.

Pedicels

(0.5–)1–1.8(–2.2) mm, gland-dotted, sparsely puberulent.

0.4–1 mm, eglandular, sparsely pubescent.

Flowers

calyx tube turbinate to narrowly campanulate, (2–)2.2–3.2(–3.5) mm, distal 1/2 often gland-dotted, glabrous or glabrate;

lobes: abaxial lobe narrowly triangular, slightly longer, adaxial lobes triangular or obtuse, 0.8–1.8(–2) mm;

banner violet or white, broadly obcordate, (4.5–)5–6(–7) × 3–4.5 mm, distinctly clawed, margins entire or finely erose;

filaments 6–9 mm, distinct;

anthers yellowish;

ovary glabrous.

calyx tube turbinate to narrowly campanulate or cylindric, 1.7–2.2 mm, distal 1/3–2/3 rarely gland-dotted, glabrous;

lobes: abaxial lobe acuminate, slightly longer, adaxial lobes triangular to acuminate, 0.4–1.2(–1.5) mm, margins densely ciliate;

banner bright blue, broadly obovate to obcordate, (4–)5–6 × 3–3.5(–4) mm, distinctly clawed, margins entire or finely erose;

filaments 5–8 mm, distinct;

anthers yellow;

ovary pubescent.

Legumes

sessile, 4–6.5 × 1.8–2.5 mm, margins strongly curved outward abaxially, straight to slightly arched adaxially, distal 2/3 gland-dotted, glabrous.

sessile or stipitate, 4–5.5 × 2–2.5 mm, margins curved outward abaxially, straight adaxially, at least distal 1/2–2/3 gland-dotted, glabrous.

Seeds

not seen.

olive brown or brown, 2–2.3 × 1–1.5 mm, smooth, lustrous.

Amorpha crenulata

Amorpha confusa

Phenology Flowering Feb–Aug(–Nov). Flowering (May–)Jun–Jul.
Habitat Rocky margins of pine woodlands and coastal prairies of the Miami Rock Ridge. Pine woodlands, savannas, and road banks in outer Atlantic Coastal Plain.
Elevation 0–10 m. (0–0 ft.) 0–50 m. (0–200 ft.)
Distribution
from FNA
FL
from FNA
NC; Pine woodlands; savannas; and road banks in outer Atlantic Coastal Plain
[BONAP county map]
Discussion

Amorpha crenulata is restricted to the Miami Rock Ridge of southeastern Florida, where about 350 individuals remain in four populations confined to Miami-Dade County. Conservation measures for this species, including an ex situ collection, restored populations, and seed bank, are overseen by Fairchild Tropical Garden in Coral Gables (for example, J. Roncal et al. 2006; K. S. Wendelberger et al. 2007).

Amorpha crenulata is in the Center for Plant Conservation’s National Collection of Endangered Plants; as A. herbacea var. crenulata, it is listed in NatureServe as a plant of concern.

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

Amorpha confusa is known presently only from Brunswick and Columbus counties; it is believed to be extirpated in adjacent South Carolina. The taxon is a Federal species of concern and is listed as threatened in North Carolina. It is usually encountered growing in loamy soils, most often of the Foreston soil series.

(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. fruticosa, A. georgiana, A. glabra, A. herbacea, A. laevigata, A. nana, A. nitens, A. ouachitensis, A. paniculata, A. roemeriana, A. schwerinii
A. californica, A. canescens, A. crenulata, A. fruticosa, A. georgiana, A. glabra, A. herbacea, A. laevigata, A. nana, A. nitens, A. ouachitensis, A. paniculata, A. roemeriana, A. schwerinii
Synonyms A. herbacea var. crenulata A. georgiana var. confusa
Name authority Rydberg in N. L. Britton et al.: N. Amer. Fl. 24: 30. (1919) (Wilbur) S. C. K. Straub: Sorrie & Weakley, J. Bot. Res. Inst. Texas 3: 154. (2009)
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