Indigofera caroliniana

Indigofera caroliniana
Photo by Karan A. Rawlins, University of Georgia, Bugwood.org
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta - Flowering plants
Class:	Magnoliopsida – Dicotyledons
Order:	Fabales
Family:	Fabaceae ⁄ Leguminosae
Genus:	Indigofera
Species:	I. caroliniana
Binomial name
Indigofera caroliniana Mill.
Natural range of Indigofera caroliniana from USDA NRCS Plants Database.

Common name: Carolina indigo; wild indigo

Taxonomic notes

Synonyms: none

Varieties: none

Description

Where this species is found, it is frequent.

"Suffruticose herb 0.5-1.2 (2) m tall. Leaves odd-pinnate, 5-10 cm long with a slightly strigillose rachis; leaflets 9-15, mostly obovate to oblanceolate, 1-2.5 cm long, 5-10 mm wide, minutely strigillose on both surfaces, trichomes appearing as though attached at their middle, stipellate. Racemes pedunculate, axillary or terminal, 6-20 cm long usually longer than subtending leaf, slender, with numerous, loosely arranged flowers; pedicel ca. 1 mm long, subtended by a triangular, subulate bract 0.8-1 mm long, lobes 0.20.4 mm long; petals pinkish to yellowish-brown, the standard and keel 5-6 mm long, the wings 1-2 mm shorter and adherent to the laterally pouched keel petals; stamens diadelphous, 9 and 1, with the connective extended above the anthers. Legume 5-10 mm long, short-stipitate, beaked, 1-3 seeded."

The root system of Indigofera caroliniana includes stem tubers which store non-structural carbohydrates (NSC) important for both resprouting following fire and persisting during long periods of fire exclusion. Diaz-Toribio and Putz (2021) recorded this species to have an NSC concentration of 152.6 mg/g (ranking 37 out of 100 species studied) and water content of 62.7% (ranking 73 out of 100 species studied).

According to Diaz-Torbio and Putz (2021), Indigofera caroliniana has stem tubers with a below-ground to above-ground biomass ratio of 3.04 and nonstructural carbohydrate concentration of 152.6 mg g^-1.

Distribution

Indigofera caroliniana is distributed from eastern North Carolina south to southern Florida, and west to southeastern Louisiana. It is considered a Southeastern Coastal Plain endemic species.

Ecology

Habitat

Generally, this species can be found in sandhills, maritime forests, Florida scrub habitats, and other sandy woodlands or forests. It is found along the edges of flatwoods, mixed woodlands, upland ridges, deciduous forests, slash pine-hardwood stands, sand pine scrub, and sand ridges. This species grows in sand and sandy loam in open areas. This species also occurs outside of its natural environments in human-disturbed areas such as open fields, bulldozed scrub oak sandhills, clobbered slash pine and hardwood fields, and wood pastures.

Associated species include Longleaf pine, turkey oak, slash pine, sand live oak, myrtle oak, sand pine, chapman oak, Cuthbertia, Rhynchosia, and Pediomelium, shortleaf pine, red oak, mockernut hickory, wiregrass, and bluejack oak.

Phenology

I. caroliniana generally flowers from June until August, and fruits from July until October. It has been observed flowering in April, June through August, and in December with peak inflorescence in July. It has been observed fruiting June through September.

Fire ecology

This species occurs in areas that are burned.

Pollination

Indigofera caroliniana has been observed at the Archbold Biological Station to host sweat bees such as Lasioglossum placidensis (family Halictidae) and leafcutting bees such as Anthidiellum perplexus (family Megachilidae). Other members of the Hymenoptera order that have been observed pollinating I. caroliniana include Dialictus placidensis.

Conservation, cultivation, and restoration

Since the overall range is restricted of this species, it is listed on the global scale as G4, but it is relatively common in the region. It is also listed as vulnerable by the state of North Carolina.