Indigofera arrecta Hochst.
Fabaceae
Java Indigo

originating from East- and South Africa, I. arrecta is found throughout the world's tropical regions today. it's dispersion is largely due to the growth of indigo production in the European Colonies. it was taken to Indoneisa where, in the 19th century, is was widely grown and known as 'indigo du natal'. The same plant was later grown in India under the name 'java indigo'. in comparison to indigenous indigo plants, the Indiofera arrecta contains greater quantity of pigment. this species became the economically most important indigo in india and provided the greatest percent of the yearly harvests. today it is still grown and it's indigo extracted on a limited scale, but it is commonly grown as a green-manure and as ground cover in plantations of Coffee (Coffea), Tea (Camelia) and Kautschuk (Hevea brasiliensis).

Indigofera suffruticosa Mill.
Fabaceae
Mayo Indigo

this indigo comes from the Sonora desert in Mexico. mayo indigo was used by the American natives for thousands of years before the Conquest and is found from mexico over the whole of the tropical Americas. In the 18th and 19th centuries this plant played an important role in indigoproduction in China, Africa and NorthAmerica. In Sonora the bush grows on irrigated sand bars on the Rio Mayo where its leaves are still collected for traditional dyeing by the tribes there.

Persicaria tinctoria Spach
Polygonaceae
China Indigo, Dyer's knotweed

this plant from subtropical China called 'liao-lan' is also found in Vietnam, Korea and Japan. Actually a biennial plant, these are normally farmed as an annual crop. indigo production with this form of indigo is similar to that of Woad, Isatis sp., but yields a greater quantity of indigo pigment. Formerly known as Polygonum tinctorum, it is still farmed for traditional dyeing in China and Japan. unlike Woad, the Persicaria tinctoria is also suitable to making dyevats direct with fresh plant material.

Isatis tinctoria L.
Brassicaceae
Woad

Woad is a biennial plant, from which only the first season's leaves are used to dye blue. it has a very small content of pigment which requires specialized processing to concentrate. Since Neolithic times woad has been used in Europe and the Middle East it's use was very early replaced by the tropical indigos. recently in Europe scientists have developed new bacteria which simplify the extraction process and hail a possible revival of this crop. woad dye can be used as a printing ink.