''Indigofera'' is a large genus of over 750 species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s belonging to the pea family

Fabaceae Fabaceae () or Leguminosae,International Code of Nomen ...

. They are widely distributed throughout the

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

and

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...

regions of the world.

Description

''Indigofera'' is a varied genus that has shown unique characteristics making it an interesting candidate as a potential perennial crop. Specifically, there is diverse variation among species with a number of unique characteristics. Some examples of this diversity include differences in

pericarp Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Fruitlike structures may develop directly from the seed itself rather th ...

thickness, fruit type, and flowering morphology. The unique characteristics it has displayed include potential for mixed

smallholder A smallholding or smallholder is a small farm operating under a small-scale agriculture model. Definitions vary widely for what constitutes a smallholder or small-scale farm, including factors such as size, food production technique or technolo ...

systems with at least one other species and a resilience that allows for constant nitrogen uptake despite varying conditions.

Tree

Species of ''Indigofera'' are mostly shrubs, though some are small trees or herbaceous perennial plant, perennials or annual plant, annuals. The branches are covered with silky hairs. Most of them have pinnate leaves made of three foliolates with short petioles. Small flowers grow in the leaf axils from long peduncles or spikes, their petals come in hues of red or purple, but there are a few greenish-white and yellow-flowered species. Indigofera flowers have open carpels, their organ primordial is often formed at deeper layers than other eudicots. This variety could have significant implications on its role in an actual perennial polyculture. For example, different flowering morphologies could be artificially selected for in varying directions in order to better fit in different environmental conditions and with different populations of other plants.

Fruit

The fruit is a long, cylindrical legume pod of varying size and shape. The types of fruit produced by different species of ''Indigofera'' can also be divided into broad categories that again show great variation. The three basic types of fruit categories can be separated by their curvature including straight, slightly curved, and falcate (sickle-shaped). In addition, several of the species, including ''Indigofera suffruticosa'' and ''Indigofera microcarpa'', have shown delayed dehiscence (maturing) of fruits. This variation could again allow for artificial selection of the most abundant and nutritious fruit types and shapes. Another way to categorize ''Indigofera'' is by its

thickness. The pericarp (the tissue from the ovary that surrounds the seeds) can be categorized as type I, type II, and type III with type I having the thinnest pericarp and fewest layers of schlerenchymatous (stiff) tissue and type III having the thickest pericarp and most schlerenchymatous layers. Despite the previous examples of delayed dehiscence, most fruits of this genus show normal explosive dehiscence to disperse seeds. Similar to fruit shape, the variation in fruit sizes allows for the thickest and most bountiful fruits to be selected.

Species

, Plants of the World Online accepted over 760 species worldwide. Selected species: *''Indigofera astragalina'' DC. *''Indigofera australis'' Willd. *''Indigofera candicans'' Aiton *''Indigofera cassioides'' Rottler ex DC. *''Indigofera cloiselii'' Drake *''Indigofera cordifolia'' B.Heyne ex Roth *''Indigofera decora'' Lindl. *''Indigofera galegoides'' DC. *''Indigofera georgei'' E.Pritz. *''Indigofera glaucescens'' Eckl. & Zeyh. *''Indigofera hendecaphylla'' Jacq. *''Indigofera heterantha'' Wall. ex Brandis *''Indigofera hilaris'' Eckl. & Zeyh. *''Indigofera himalayensis'' Ali *''Indigofera hirsuta'' L. *''Indigofera howellii'' Craib & W.W.Sm. *''Indigofera kirilowii'' Maxim. ex Palibin *''Indigofera linifolia'' (L.f.) Retz. *''Indigofera marmorata'' Balf.f. *''Indigofera miniata'' Ortega *''Indigofera nephrocarpoides'' J.B.Gillett *''Indigofera nummulariifolia'' (L.) Livera ex Alston *''Indigofera pendula'' Franch. *''Indigofera rothii'' Baker *''Indigofera sokotrana'' Vierh. *''Indigofera spicata'' Forssk. *''Indigofera suffruticosa'' Mill. *''Indigofera szechuensis'' Craib *''Indigofera tinctoria'' L. *''Indigofera tsiangiana'' Metcalf

Ecology

''Indigofera'' species are used as food plants by the larvae of some Lepidoptera species, including the turnip moth (''Agrotis segetum'').

Uses

Indigo dye

Several species, especially ''Indigofera tinctoria'' and ''Indigofera suffruticosa'', are used to produce the dye Indigo dye, indigo. Scraps of Indigo-dyed fabric likely dyed with plants from the genus ''Indigofera'' discovered at Huaca Prieta predate Egyptian indigo-dyed fabrics by more than 1,500 years. Colonial planters in the Caribbean grew indigo and transplanted its cultivation when they settled in the colony of South Carolina and North Carolina where people of the Tuscarora people, Tuscarora confederacy adopted the dyeing process for head wraps and clothing. Exports of the crop did not expand until the mid-to late 18th century. When Eliza Lucas Pinckney and Atlantic slave trade, enslaved Africans successfully cultivated new strains near Charleston, South Carolina, Charleston it became the second most important cash crop in the colony (after rice) before the American Revolution. It comprised more than one-third of all exports in value. The chemical aniline, from which many important dyes are derived, was first synthesized from ''Indigofera suffruticosa'' (synonym (taxonomy), syn. ''Indigofera anil'', whence the name aniline). In Indonesia, the Sundanese people, Sundanese use ''Indigofera tinctoria'' (known locally as :id:Tarum, tarum or :ms:Nila, nila) as dye for batik. Marco Polo was the first to report on the preparation of indigo in India. Indigo was quite often used in European easel painting during the Middle Ages.

References

External links

''Indigofera''.
eFloras Lists. * {{Authority control Indigofera, Fabaceae genera Plant dyes Pantropical flora