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partridge pea, sensitive partridge or wild sensitive pea, sensitive partridge pea, wild sensitive-pea

Photo is of parent taxon
Habit Herbs, annual, rarely over-wintering, to 0.8(–1)[–1.2] m. Stems erect, incurved ascending. Herbs to 0.6(–0.8) m. Stems glabrous or hairs whitish, to 0.7 mm.
Leaves

(1.5–)2–8(–9)[15–21] cm;

petiole (1.5–)2–7 mm;

extrafloral nectary 1(or 2), near mid petiole, stipitate;

leaflets (6–)8–28(–32)[–40] pairs, blades usually straight, sometimes falcate, linear, narrowly oblong, or oblong-elliptic, (3–)4–26 × 1–3 mm.

(2–)2.5–8(–9) cm;

stipules usually persistent;

petiole (1.5–)2–5(–6) mm, usually glabrous;

leaflets (7–)10–22(–25) pairs, blades (3–)4–14 × 1–3 mm, margins ciliolate, some hairs 0.4+ mm.

Racemes

1(or 2)-flowered, axillary.

Pedicels

0.5–4[–16] mm;

bracteoles mid pedicel.

0.5–4 mm.

Flowers

calyx greenish, sepal venation reticulate;

corolla yellow, sometimes fading pinkish, petals to 3.5–8(–9)[–16] mm;

stamens [2–]4–8[or 9];

anthers yellow-orange or red, to (1.4–)1.6–3[–9.5] mm, different sizes;

ovary usually hairy throughout, rarely glabrate.

corolla often fading pinkish, petals to 3.5–7(–7.5) mm;

stamens (4 or)5–8, staminodia 0;

anthers to 2–3 mm;

ovary hairy throughout;

ovules 8–19.

Legumes

straight, linear-oblong, [14–](15–)18–48(–56)[–78] × [2.4–]2.5–5.5(–5.8) mm.

(17–)20–48(–56) × 2.5–3.8(–4) mm.

Seeds

[1.9–](2.2–)2.4–3.4[–3.7] mm.

2.5–3.2 mm.

Chamaecrista nictitans

Chamaecrista nictitans var. leptadenia

Phenology Flowering mid summer–mid fall.
Habitat Arid grasslands, desert slopes and washes, thorn-forests, open spaces in pine and oak forests.
Elevation 10–2000 m. (0–6600 ft.)
Distribution
from USDA
United States; Mexico; Central America; West Indies; South America (Argentina, Brazil, Paraguay, Peru)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; NM; TX; Mexico (Baja California, Chihuahua, Durango, Guerrero, Jalisco, Nayarit, Oaxaca, Sinaloa, Sonora)
Discussion

Varieties 13 (3 in the flora).

Chamaecrista nictitans is distinguished from the closely similar C. fasciculata (and C. deeringiana) by its globose-ovoid floral buds, which are ovoid-acuminate in the latter two species. All three varieties in the flora area belong to subsp. nictitans and are characterized by two to nine fertile stamens, while all other varieties have ten fertile stamens (they belong to the other subspecies): subsp. brachypoda (Bentham) H. S. Irwin & Barneby, subsp. disadena (Steudel) H. S. Irwin & Barneby, and subsp. patellaria (Colladon) H. S. Irwin & Barneby (H. S. Irwin and R. C. Barneby 1982). The key to varieties in the flora is adapted from Irwin and Barneby.

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

Variety leptadenia is known from Cochise, Gila, Graham, Greenlee, Pima, Pinal, and Santa Cruz counties in Arizona, Doña Ana, Grant, Hidalgo, and Luna counties in New Mexico, and Brewster, Jeff Davis, and Presidio counties in Texas.

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

Key
1. Leaflet blade margins ciliolate, some hairs 0.4+ mm; ovules 8–19.
var. leptadenia
1. Leaflet blade margins glabrous or hairs to 0.4 mm; ovules 5–10.
→ 2
2. Stems and petioles glabrous or hairs whitish, to 0.7 mm.
var. nictitans
2. Stems and petioles covered with hairs yellow or orange reddish, 1–2.5 mm.
var. aspera
Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Caesalpinioideae (excluding Mimosoid clade) > Chamaecrista Fabaceae > subfam. Caesalpinioideae (excluding Mimosoid clade) > Chamaecrista > Chamaecrista nictitans
Sibling taxa
C. absus, C. calycioides, C. chamaecristoides, C. deeringiana, C. fasciculata, C. flexuosa, C. greggii, C. lineata, C. pilosa, C. rotundifolia, C. serpens
C. nictitans var. aspera, C. nictitans var. nictitans
Subordinate taxa
C. nictitans var. aspera, C. nictitans var. leptadenia, C. nictitans var. nictitans
Synonyms Cassia nictitans Cassia leptadenia, C. leptadenia var. mensalis, C. leptadenia, C. nictitans var. mensalis
Name authority (Linnaeus) Moench: Methodus, 272. (1794) (Greenman) Gandhi & S. L. Hatch: Sida 13: 123. (1988)
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