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Sonoran indigo, Sonoran indigobush

mu lan, true indigo

Habit Shrubs or subshrubs (woody), strigose, hairs appressed. Herbs or subshrubs, perennial, pubescent, hairs appressed, silvery, young growth and flowering parts covered with brownish hairs, becoming glabrate.
Stems

erect, diffusely branched, 3–15 dm.

erect or ascending, much branched, 5–20 dm.

Leaves

2.5–9 cm;

stipules linear-triangular, 1–2 mm;

petiole 0.3–1.5 cm;

stipels 0.5 mm;

petiolules 1.3 mm;

leaflets 13–19, opposite, blades elliptic to obovate-oblong, sometimes folded, 20–30 × 2–5 mm, base cuneate, apex broadly rounded or truncate, mucronate, surfaces strigose and pale abaxially, glabrate adaxially.

3–10 cm;

stipules caducous, subulate, 1–2 mm;

petiole 0.4–1.2 cm;

stipels 1–1.5 mm;

petiolules 1–1.5 mm;

leaflets 7–15, opposite, blades broadly oblanceolate to obovate or elliptic, 10–25 × 3–10 mm, base cuneate, apex broadly rounded or truncate, slightly apiculate, surfaces pubescent abaxially, glabrous adaxially.

Racemes

20–35+-flowered, lax, 2.5–11 cm.

5–25-flowered, dense, 0.5–4.5 cm.

Peduncles

0.8–1.2 cm.

0.1–0.5 cm.

Pedicels

1–2 mm.

1–2 mm.

Flowers

4.5–5.2 mm;

calyx 1.5–2 mm, lobes broadly triangular;

corolla orange-mauve or pinkish.

5–6 mm;

calyx 1.5 mm, lobes triangular;

corolla pink or salmon pink.

Legumes

brown, divergent or deflexed, ellipsoidal, straight, 3–3.5 mm, leathery, glabrate.

red-brown or dark brown, spreading or reflexed, cylindric, straight or slightly curved or abruptly upturned distally, 20–35 mm, thinly leathery, strigose.

Seed(s)

1, brown, bluntly ellipsoidal.

6–12, greenish to dark brown, cuboid-ellipsoidal.

2n

= 16.

Indigofera sphaerocarpa

Indigofera tinctoria

Phenology Flowering Jul–Oct. Flowering year-round.
Habitat Dry, rocky slopes, with grasses, oaks. Ruderal areas, disturbed pinelands, hammocks.
Elevation 1000–1800 m. (3300–5900 ft.) 0–200 m. (0–700 ft.)
Distribution
from FNA
AZ; CA; NM; Mexico (Chihuahua, Jalisco, Sonora)
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; FL; NC; SC; TN; s Asia (India) [Introduced in North America; introduced also in Mexico (Tabasco), West Indies (Bahamas, Cayman Islands, Cuba, Hispaniola, Jamaica, Lesser Antilles, Puerto Rico, Virgin Islands), Central America, South America (Argentina, Venezuela), elsewhere in Asia, Africa, Australia]
[BONAP county map]
Discussion

Indigofera sphaerocarpa is known in the flora area from Cochise, Graham, Pima, and Santa Cruz counties, Arizona, and Hidalgo County, New Mexico. A single specimen from the Joshua Tree National Monument, Riverside County, California, was collected in 1973 (Smith & Sawyer 6890, HSC).

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

Indigofera tinctoria was an early source of a blue fabric dye (J. A. Duke 1981). It was widely cultivated in tropical areas around the world, and it has naturalized in many regions. Use of the plant as a dye source waned after introduction of a synthetic dye.

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

Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Indigofera Fabaceae > subfam. Faboideae > Indigofera
Sibling taxa
I. caroliniana, I. colutea, I. decora, I. hirsuta, I. kirilowii, I. lindheimeriana, I. miniata, I. oxycarpa, I. pilosa, I. spicata, I. suffruticosa, I. texana, I. tinctoria
I. caroliniana, I. colutea, I. decora, I. hirsuta, I. kirilowii, I. lindheimeriana, I. miniata, I. oxycarpa, I. pilosa, I. sphaerocarpa, I. spicata, I. suffruticosa, I. texana
Synonyms Amorpha ovalis, Anila sphaerocarpa Anila tinctoria
Name authority A. Gray: Smithsonian Contr. Knowl. 5(6): 37. (1853) Linnaeus: Sp. Pl. 2: 751. (1753)
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