Isatis

This plant, known as Isatis tinctoria, is still grown in France and Flanders.

Beric the Briton : a Story of the Roman Invasion 1867

Important sources were Isatis tinctoria (woad rather than indigo proper), native to northern Europe and Britain; Indigofera tinctorium, imported from India; and Indigofera suffructicosa, imported from the Americas.

The Creation of Color in Eighteenth-Century Europe 2006

Isatis I. indigotica or I. tinctoria, also known as da qing ye in Traditional Chinese Medicine, contains indican and isatin B among other compounds and is known to have potent antibacterial properties against staphylococci, pneumococci, and meningococci, which means that it is useful for virtually all common bacterial infections.

THE NATURAL REMEDY BIBLE JOHN LUST 2003

Woad (_Isatis tinctoria_) and the dyers 'yellow woad (_Reseda lutea_), are both well known.

The Commercial Products of the Vegetable Kingdom Considered in Their Various Uses to Man and in Their Relation to the Arts and Manufactures; Forming a Practical Treatise & Handbook of Reference for the Colonist, Manufacturer, Merchant, and Consumer, on the Cultivation, Preparation for Shipment, and Commercial Value, &c. of the Various Substances Obtained From Trees and Plants, Entering into the Husbandry of Tropical and Sub-tropical Regions, &c. P. L. Simmonds

The _Wrightia tinctoria_, of the East Indies, an evergreen, with white blossoms, affords some indigo, as does the _Isatis tinctoria_, or,

The Commercial Products of the Vegetable Kingdom Considered in Their Various Uses to Man and in Their Relation to the Arts and Manufactures; Forming a Practical Treatise & Handbook of Reference for the Colonist, Manufacturer, Merchant, and Consumer, on the Cultivation, Preparation for Shipment, and Commercial Value, &c. of the Various Substances Obtained From Trees and Plants, Entering into the Husbandry of Tropical and Sub-tropical Regions, &c. P. L. Simmonds

Woad is derived from a plant, _Isatis tinctoria_, growing in the North of France and in England.

Vegetable Dyes Being a Book of Recipes and Other Information Useful to the Dyer Ethel M. Mairet

They are all species of the genera _Indigofera_, _Isatis_ and _Nerium_.

The Commercial Products of the Vegetable Kingdom Considered in Their Various Uses to Man and in Their Relation to the Arts and Manufactures; Forming a Practical Treatise & Handbook of Reference for the Colonist, Manufacturer, Merchant, and Consumer, on the Cultivation, Preparation for Shipment, and Commercial Value, &c. of the Various Substances Obtained From Trees and Plants, Entering into the Husbandry of Tropical and Sub-tropical Regions, &c. P. L. Simmonds

There is a vegetable dye obtained from _Isatis indigotica_ much used in the northern districts, and called _Teinsing_; and it is not unlikely that it may be the substance which is employed.

The Commercial Products of the Vegetable Kingdom Considered in Their Various Uses to Man and in Their Relation to the Arts and Manufactures; Forming a Practical Treatise & Handbook of Reference for the Colonist, Manufacturer, Merchant, and Consumer, on the Cultivation, Preparation for Shipment, and Commercial Value, &c. of the Various Substances Obtained From Trees and Plants, Entering into the Husbandry of Tropical and Sub-tropical Regions, &c. P. L. Simmonds

Polygonum dumetorum, Isatis tinctoria, and Impatiens fulva, an American species of balsam, affording a very remarkable example of complete naturalization in the Wey and other streams connected with the lower course of the Thames.

John Stuart Mill; His Life and Works Spencer, Herbert 1873

Guildford and the beautiful vale of the Sittingbourne, where he had the satisfaction of being the first to notice several plants of interest, as _Polygonum dumetorum_, _Isatis tinctoria_, and _Impatiens fulva_, an American species of balsam, affording a very remarkable example of complete naturalization in the Wey and other streams connected with the lower course of the Thames.

John Stuart Mill; His Life and Works Twelve Sketches by Herbert Spencer, Henry Fawcett, Frederic Harrison, and Other Distinguished Authors Herbert Spencer 1861