The goals of this project were to determine which taxa of
Indigofera occur in Alabama and to report the distribution of each.
Indigofera (Fabaceae), commonly known as indigo, consists of four
species in Alabama. The most common species is I. caroliniana Miller.
The less common species are I hirsuta Linnaeus, I tinetoria Linnaeus and
I miniata Ortega var leptosepala (Nuttall ex Torrey & A. Gray) B. L.
Turner. The dichotomous key and descriptions were generated based on
morphological features of vegetative and reproductive structures
reported in the literature and of more than 200 specimens studied.
County-level distribution maps were compiled entirely from herbaria
Indigofera, commonly known as indigo, is a member of the legume
family Fabaceae (Leguminosae), subfamily Papilionoideac, tribe
Indigoferinae (Schrire, 1995). The Indigoferinae, primarily a tribe of
the Old World tropics, is recognized as being derived from a woody
Tephrosieae (=Millettieae) (Pohill, 1981). Findings by Doyle et al.
(1997), using rbcL sequence data, support this classification.
Indigofera consists of approximately 700 species worldwide and
occurs on all major land masses, but is most abundant in Africa and Asia
(Isely, 1990). In the United States, Indigofera consists of both native
and introduced taxa (Isely, 1990). Fifteen species and four
infraspecific taxa of have been reported from the United States. Of
these, 12 species have been reported from the southeastern United States
(USDA, NRCS, 2010).
Indigofera tinctoria Linnaeus was introduced into the United States
in the seventeenth century and cultivated as a source of indigo dye,
which was an important commodity of commerce until it was replaced by
synthetic dyes in the late nineteenth century (Isely, 1990).
MATERIALS AND METHODS
Distribution maps are based on more than 200 plant specimens
deposited in the herbaria of Troy University (TROY), J. D. Freeman
(AUA), The University of Alabama (UNA), The University of South Alabama
(USAM), Jacksonville State University (JSU), University of North Alabama
(UNAF), and Vanderbilt University (VDB), which is housed at the
Botanical Research Institute of Texas (BRIT) in Fort Worth.
Herbarium specimens were initially divided into groups based on
overall morphological similarity and the species concept established by
Isely (1990). The dichotomous key is a modification of Isely (1990) and
Weakley (2007). Descriptions for each taxon are based on Isely (1990).
For Indigofera caroliniana Miller and I. hirsuta Linnaeus, morphological
measurements were taken from selected specimens from throughout the
geographical range in Alabama and incorporated into the descriptions if
they differed from Isely (1990). Since both I. tinctoria Linnaeus and I.
miniata Ortega var. leptosepala (Nuttall ex Torrey & A. Gray) B. L.
Turner are known from single collections in the state, morphological
measurements are entirely from Isely (1990), which allows for the range
of variation throughout the southeastern United States. Illustrations
are by the first author. The lists of specimens examined are limited to
one record from each county.
Four species of Indigofera occur in Alabama. The most common
species is I. caroliniana Miller (14 counties). The less common species
are I. hirsuta Linnaeus (three counties),I. tinctoria Linnaeus (one
county) and I. miniata Ortega var. leptosepala (Nuttall ex Torrey &
A. Gray) B. L. Turner (one county).
TAXONOMIC TREATMENT OF INDIGOFERA
Indigofera Linnaeus, Sp. Pl. 751. 1753.
Anil(Ludwig)Miller, Gard. Diet. abr. ed. 4. 1754.
Bremontiera de Candolle, Mem. Legum. part 5. Paris. 249-312. 1825.
Hemispodon Endlicher, Flora. 15: 385. 1832.
Eilemanthus Hochstetter. Flora. 29: 593. 1846.
Amecarpus Bentham, Lindl. Veg. Kingd. 554. 1847.
Indigastrum Jaubert & Spach, Illust. Pl Orient, pl. 492. 1857.
Anila Kuntze, Rev. Gen. 160. 1891.
Vaughania S. Moore. J. Bot. 58: 188. 1920.
Herbs or shrubs. Stems prostrate, sprawling, ascending or erect,
strigose, pilose or hirsute. Leaves odd pinnate (-trifoliolate),
petioled; leaflets paired, alternate, or irregularly arranged, entire;
stipules free, persistent or caducous. Inflorescences axillary; bracts
caducous. Calyx broad, bowl-shaped, lobes subequal or unequal, shorter
or longer than tube; corolla early deciduous, reddish-orange, tinted
with pink or salmon; stamens 10, diadelphous(9 + 1); styles glabrous.
Fruits deflexed (-ascending or divergent), dehiscent (-indehiscent),
oblong, subterete or tetragonal (-laterally compressed) in cross
section, ovoid in one species, coriaceous. Seeds few to numerous.
KEY TO THE ALABAMA SPECIES OF INDIGOFERA
1. Stems hirsute or pilose; legumes hispid____1. I. hirsuta
1. Stems glabrous or appressed strigose; legumes glabrous to
2. Leaflets, at least some, alternate or irregularly arranged on
leafstalk; stipules 2-6 mm long; calyx 3-6 mm long____2. I, miniata
2. Leaflets opposite on leafstalk; stipules obsoluescent to 2 mm
long; calyx 1-2 mm long____3
3. Legumes 5-10 mm long, ovoid, straight, indehiscent; seeds 2-3;
stipules____obsoluescent; corolla 6-9 mm long____3. I. caroliniana
3. Legumes 25-35 mm long, slightly falcate, dehiscent; seeds 3-10
or more; stipules 1-2 mm long;____corolla 5-6 mm long 4. I. tinctoria
1. Indigofera hirsuta Linnaeus, Sp. Pl. 751. 1753. [Figure la]
Indigofera ferruginea Schumach & Thonner, Guin. Pl. 370. !827.
Indigofera fusca G. Don, Gen. Hist. 2: 211. 1832.
Anila hirsuta (Linnaeus) Kuntzc, Revis. Gen. PI. 2: 939. 1891.
Herbs. Stems sprawling or erect, brownish hirsute or pilose. Leaves
odd pinnate, petioles 3-8 cm long; leaflets 5-9 paired, elliptic to
obovate, 2-4 cm long, pubescent both surfaces with subappressed hairs;
stipules setaceous, to 1 cm long, persistent. Racemes 6-20 cm long,
flowers crowded, pedunculate; pedicles 1 mm long. Calyx 3.5-5 mm long,
lobes setaceous, longer than tube, bristly-plumose; corolla salmon to
maroon, 6-7 mm long. Fruits 1.5-2.0 cm long, hispid, imbricate,
deflexed, dehiscent, oblong, straight, turgid. Seeds numerous.
Native of Old World tropics, now pantropical, cultivated and
established; introduced in southern United States.
Habitat and distribution in Alabama: roadsides, old fields,
disturbed woodlands, waste areas; widely scattered in the southern
one-fourth of the state (Fig, 1 b). Specimens examined. Henry County:
Lindsay Leveret! 7, 2 October 2008 (TROY), Mobile County: Michel G.
Lelong 9572, 6 October 1976 (BRIT), Pike County: Michael Woods 10210, 22
November 2004 (TROY).
2. Indigofera miniata Ortega var. leptosepala (Nuttall ex Torrey
& A. Gray) B. L. Turner, Field & Lab. 24: 104. 1956. [Figure 1c]
Indigofera ornithopodioides Schlechtendal & Chamisso, Linnaea
5: 577. 1830.
Indigofera leptosepala Nuttall ex Torrey & A. Gray, Fl. N.
Indigofera cinerea Buckland, Proc. Acad. Phila. 1861: 451. 1861.
Indigofera texana Buckland, Proc. Acad. Phila. 1861. 451. 1861.
Anila leptosepala (Nuttall ex Torrey & A. Gray) Kuntze, Revis.
Gen. Pl. 2: 939. 1891.
Herbs. Stems prostrate or ascending, greenish or cinereous,
strigulose. Leaves odd pinnate, petioles 0.6-3 cm long; leaflets 5-9
opposite or irregularly arranged, cuneate obovate to narrowly
oblanceolate, 0.5-2.5 cm long; stipules subulate, 2-6 mm long,
semipersistent. Flowers 3-numerous initially crowded, then loosening,
shortly or well pedunculate; pedicels 1 mm long. Calyx 3-6 mm long,
lobes longer than tube, subulate; corolla salmon-red (-pink,-orange),
8-12 mm long. Fruits 1.5-2.5 cm long, coriaceous, irregularly spreading
or deflexed, dehiscent, oblong, straight, subterete. Seeds few to
Habitat and distribution in Alabama: ballast grounds in
southwestern corner of the state (Fig. 1d).
Specimens examined. Mobile County: Mohr s.n., September 1891 (UNA).
3. Indigofera caroliniana Miller, Gard. Diet., ed. 8. 1768. [Figure
Pithecellobium disperma Linnaeus, Syst. Nat., ed. 12. 3: 232. 1768.
Indigofera caroliniana Walter, Fl. Carol. 187. 1788, non Miller
Anila caroliniana Kuntze, Revis. Gen. P1. 2: 939. 1891.
Herbs. Stems erect or ascending, slightly strigose. Leaves odd
pinnate, petioles 2.5-7 cm long; leaflets (7-) 9-13 paired, obovate to
oblanceolate, 0.8-2.5 cm long, inevidently stigulose both surfaces, pale
below; stipules semipersistent. Racemes slender and lax, flowers
numerous, shortly or well pedunculate: pedicles 1-2 mm long, in fruit to
3 mm long. Calyx 1.5-2 mm long, lobes deltate, ca. 0.5 mm long, much
shorter than tube; corolla dark flesh-colored to ochroleucous (in fresh
condition with rose, tan, and yellow), 6-9 mm long. Fruits 7-9 mm long,
declined, persistent, indehiscent, ovoid or shortly oblong, compressed
but turgid. Seeds 2-3.
Habitat and distribution in Alabama: pinelands, pine-palmetto,
scrub oak communities, sandhills, and roadsides; scattered in the
southern one-half of the state, mostly in southeastern corner (Fig. 2b).
Specimens examined. Baldwin County: R. Kral 32617, 19 August 1968
(BRIT), Barbour County: John R. MacDonald 11291, 27 May 1998 (UNA),
Bullock County: A.R. Diamond 13516, 8 August 2002 (TROY), Coffee County:
Brian H. Martin 942, 4 September 2000 (TROY), Crenshaw County: A.R.
Diamond 11379, 23 August 1998 (AUA), Dale County: Tiffany Pennington
820, 27 June 2000 (TROY), Dallas County: R. Kral 32872, 22 August 1968
(BRIT), Henry County: John R. MacDonald 12880,26 May 1999 (TROY),
Houston County: John R. MacDonald 19842, 20 July 1997 (BRIT), Macon
County: DA, Botts 202, 2 July 1976 (AUA), Mobile County: C. Mohr s.n.,
July (UNA), Montgomery County: A.R. Diamond 12473, 3 July 2001 (TROY).
Pike County: James A. Hall 56, 3 July 2000 (TROY). Russell County: R.
Kral 62074, 19 June 1978 (TROY).
4. Indigofera tinctoria Linnaeus, Sp. P1. 75 1. 1753. [Figure 2c]
Indigofera anil Linnaeus var. orthocarpa de Candolle, Prodr. 2:
Indigofera indica Lamarck, Encycl. 3: 245. 1789, nom. illegit. et
non Miller 1768.
Anila tinctoria (Linnaeus) Kuntze, Revis. Gen, PI. 1: 160. 1891.
Anila tinctoria (Linnaeus) Kuntze var. normalis Kuntze, Revis. Gen.
P1. 1: 160. 1891.
Anila tinctoria (Linnaeus) Kuntze var. orthocarpa (de Candollc)
Kuntze, Revis. Gen. P1. 1: 160. 1891.
Herbs. Stems erect or ascending (-sprawling), strigulose. Leaves
odd pinnate, petioles 3-9 cm long; leaflets 9-15 paired, obovate or
elliptic, 1-2.5 cm long, glabrous above; stipules ca. 2 mm long,
caducous. Flowers closely disposed, initially subsessile, then
pedunculate; pedicles 1-2 mm long. Calyx ca. 1.5 mm long, tube and lobes
subequal; corolla reddish-orange, 5-6 mm long. Fruits crowded, 2.8-3.5
cm long, divergent to declined, deciduous, dehiscent, linear and
slightly falcate or abruptly upturned at tip, subterete, usually
submoniliform, thinly coriaceous, strigose. Seeds several to numerous.
Native of tropical Africa, now widely distributed in warm regions
and tropics; introduced in southern United States.
Habitat and distribution in Alabama: ballast grounds in
southwestern corner of the state (Fig. 2d).
Specimens examined. Mobile County: Mohrs.n., October 1869 (UNA).
In Alabama, Indigofera is a conspicuous taxon of pinelands, scrub
oak communities, sandhills, roadsides, old fields, disturbed woodlands
and urban waste areas.
The four taxa of Indigofera in this treatment are a combination of
native and introduced species. Indigofera caroliniana Miller is based on
a collection from "Carolina" and is the first North American
species of the genus described (Miller, 1768). This taxon is endemic to
the Southeastern United States and is known from all coastal states from
North Carolina southwest to Louisiana (USDA, NRCS, 2010). Linnaeus
(1753) described I. hirsuta based on a specimen collected from India.
Presently, it has escaped cultivation in the United States and has been
reported from Alabama, Florida, Georgia and South Carolina (USDA, NRCS,
2010). Although known from only three populations in Alabama, this taxon
appears to be becoming more common in the southern section of the state,
where two of the three known populations have been discovered in the
past five years. Ortega (1798) described I. miniata based on a specimen
collected from Cuba. This taxon is considered native to the United
States and has been reported from Alabama, Arkansas, Georgia, Kansas,
Louisiana, Oklahoma and Texas (USDA, NRCS, 2010). The Alabama collection
is represented by l. miniata Ortega var. leptosepala (Nuttall ex Torrey
& A. Gray) B. L. Turner. It is known from a single historical
collection, September 1891, from ballast grounds in Mobile County.
Although this taxon has not been reported from the state in 119 years,
Alabama is in its natural range (Florida to Texas) and it possibly still
occurs in the stale. Indigofera tinctoria is the type of the genus and
was described by Linnaeus (I 753) based on a specimen collected from
India. In the United States, this taxon has escaped cultivation and has
been collected in Alabama, Florida, North Carolina, South Carolina and
Tennessee (USDA, NRCS, 2010). In Alabama, it is known from a single
historical collection, October 1869, from ballast grounds in Mobile
County. Since these ballast grounds have been developed, it is likely
that this taxon is extirpated from the state.
[FIGURE 1 OMITTED]
[FIGURE 2 OMITTED]
The authors thank the curators of the herbaria which loaned
specimens for this study. This research was supported by a Blanche E.
Dean Scholarship from the Alabama Wildflower Society, which was
presented to the second author.
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Kajita, T. and Ohashi, H. 1997. A phylogeny of the chloroplast gene rbcL
in the Leguminosae: taxonomic correlations and insights into the
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University of North Carolina Press, Chapel Hill, North Carolina, USA.
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Ortega, C. G. 1798. Novarum aut Rariorum Plantarum Horti Reg.
botan. Matrit. Descriptionum decades, cum nonnullarum iconibus. 8: 98.
Polhill, R. M. 1981. Papilionoideae. Pp. 191-208 in Polhill, R.M.
& Raven. P.H. (eds). Advances in Legume Systematics 2. Royal Botanic
Gardens, Kew, England.
Schrire, B. D. 1995. Evolution of the tribe Indigoferinae
(Leguminosae Papilionoideae). Pp. 161-244 in Crisp, M.D. & Doyle,
J.J. (eds), Advances in Legume Systematics 7. Royal Botanic Gardens,
USDA, NRCS. 2010. The PLANTS Database (http://plants.usda.gov, 19
February 2010). National Plant Data Center, Baton Rouge, Louisiana, USA.
Weakley, A. S. 2007. Flora of the Carolinas, Virginia, and Georgia,
working draft: January 2007. University of North Carolina Herbarium,
North Carolina Botanical Garden, Chapel Hill, North Carolina. USA.
Michael Woods and Lindsay Leverett Department of Biological and
Environmental Sciences Troy University Troy, Alabama 36082
Correspondence: Woods, Michael (email@example.com)