182 TETRADYNAMIA— SILICULOSA. Isatis. 



Germ, roundish, compressed. Style none. Stigma capi- 

 tate, sessile. Pouch oblong, obtuse, compressed, of 1 cell 

 and 2 valves, their keels flat and bordered. Seed solitary, 

 ovate-oblong, pendulous at the top of the cell ; cotyledons 

 flattish, incumbent. 



Annual or biennial, tall, upright, rather glaucous herbs, 

 with a branched corymbose stem. Lower leaves stalked ; 

 upper sessile, clasping and arrow-shaped ; all generally, 

 but not always, very smooth. Clusters many-flowered, 

 compound; sometimes accompanied, on their main stalks, 

 with diminished leaves, but destitute of true bracteas. Fl. 

 yellow. 



DeCandoUe enumerates 17 species, all yielding, by mace- 

 ration, more or less of a blue sediment, similar to indigo, 

 and like that substance useful for dyeing. 



1. I. tinctoria. Dyer's Woad. 



Radical leaves copiously crenate ; those of the stem entire. 

 Pouch abrupt, smooth, thrice as long as broad. 



I. tinctoria. Linn. Sp. PL 936. Willd. v. 3.420. Fl. Br. 693. Engl. 

 Bot. V. 2. t. 97. Mart. Rust. t.4\. DeCand. Syst. v. 2. 569. 



I. n. 523. Hall. Hist. v.\. 224. 



I. sylvestris. Fuchs. Hist. 332./. Matth. Valgr.v. 1.582./. Camer. 

 Epit.4\0.f. Dalech. Lugd. 499./. Schreh. Waidt, 9. 1. 1—3. 



Glastum sativum. Rail Syn. 307. 



G. sylvestre. Ger. Em.49\.f. 



In cultivated fields, and about their borders, but rare. 



At New Barnes near Ely. Relhan. Near Durham. Mr.E.Rohson. 



Biennial. July. 



Root tapering. Stem about 2 feet high, wand-like, slightly glau. 

 cous, leafy, panicled at the top. Radical leaves numerous, obo- 

 vate, crenate and wavy, smooth, except an occasional marginal 

 fringe ; the rest sessile, arrow-shaped, entire, smooth, clasping 

 the stem. Panicle of many compound racemose branches, beset 

 with diminished lanceolate leaves, like bracteas, all of a yellow 

 hue as well as the stalks. Fl. numerous, small, bright yellow. 

 Pouches on capillary stalks, pendulous, wedge-shaped, obtuse, 

 tipped with the stigma, quite smooth, blackish, a little shining, 

 finally bursting in the middle, where the seed is lodged. 



As the antient Britons are reported to have painted their bodies 

 with the blue colour obtained from this plant, and still used in 

 dyeing, the Woad is most probably an original production of 

 our island j though what occurs now and then, about cultivated 

 fields, is supposed to have escaped from the crops occasionally 

 raised, chiefly in the middle part of England. The naturalized 

 plants are less perfectly smooth, and far less luxuriant, than the 

 cultivated ones. 



