菘藍

The above first record of Isatis tinctoria from Xizang is based on Falconer s.n. (K). Isatis tinctoria is a European and probably Asian species very polymorphic in fruit shape, shape and size of auricles of cauline leaves, and the amount of indumentum. It has been cultivated since ancient times as a source of a dark blue dye (woad) obtained by fermenting the leaves and lower portions of the plant. Glabrous forms with oblong fruit and poorly developed or obtuse leaf auricles have been recognized as I. indigotica. By contrast, glabrous or hairy forms with cuneiform or oblong-triangular fruit and well-developed, often acute leaf auricles are called I. tinctoria. However, every conceivable morphological intermediate between the two forms occurs in China, as well as elsewhere in Asia, Europe, and North America, where they are introduced and naturalized.

The roots and leaves are used for medicinal purposes and a source of dye, and the seed oil is used in industry.

Biennial, rarely perennating, robust, 30-120 cm tall, glabrous to hirsute, subglacous, erect, with much branched inflorescence above. Basal leaves rosulate, oblanceolate, short-stalked, 5-15 cm long, 1-3 cm broad, very variable in size and often much larger in cultivated plants, entire or subdentate; cauline leaves 10-80 mm long, 5-25 mm broad, linear-lanceolate, auricled at base, amplexicaul, entire; uppermost much smaller. Racemes 30-80-flowered, panicled, ebracteate, increasing up to 10 (-15) cm in fruit. Flowers 4-5 mm across, yellow; pedicel 5-10 mm long in fruit, filiform, + deflexed. Sepals 2-2.5 mm long, yellowish-green. Petals 3-4.5 (-5) mm long, 1.5-2 mm broad, aobovte cuneate towards base, apex rounded. Stamens c. 2 : 2.5 mm long. Siliculae very variable in size, 10-20 mm long, 2.5-5 mm broad, oblong, tapering towards the base, with truncate to rounded apex, often somewhat broad in the middle (at locule), glabrous to puberulent; locule shorter than the apical portion of the wing; seed 3-4 mm long, 1 mm broad, oblong ellipsoid, brown.

A very polymorphic species and highly variable. Several subspecies and varieties have been recognized under it. Davis (l.c.) recognized 3 subspecies under it for Turkey. Hedge (in Rech. f.,l.c. 84) considered Isatis koelzii Rech.f. as a separate species from Isatis tinctoria, on the basis of short oblong fruits (c. 15 mm long), rounded at both ends. Fruit size is not exclusive for it and the apex is often slightly rounded in Isatis tinctoria; fruit base is always cuneate and tapering, and it is not clear as to what Hedge actually meant by rounded basal end. However, Isatis koelzii with small looking fruits and small size of plants in our area, does not justify more than a subspecific rank under Isatis tinctoria. The type race, i.e. subsp. tinctoria, is primarily an European, N. and N. E. Asian taxon, while our plants and that of Afghanistan fall under subsp. koelzii.

Herbs biennial, (30-)40-100(-150) cm tall. Stems branched above, glabrous and somewhat glaucous, or hirsute, often paniculately branched. Basal leaves rosulate; petiole 0.5-5.5 cm; leaf blade oblong or oblanceolate, (2.5-)5-15(-20) × (0.5-)1.5-3.5(-5) cm, base attenuate, margin entire, repand, or dentate, apex obtuse. Middle cauline leaves sessile; leaf blade oblong or lanceolate, rarely linear-oblong, (1.5-)3-7(-12) × (0.2-)0.8-2.5(-3.5) cm, base sagittate or auriculate and with acute or obtuse auricles, margin entire, apex acute. Fruiting pedicels slender, considerably thickened and subclavate at apex, 5-10 mm. Sepals oblong, 1.5-2.8 × 1-1.5 mm, glabrous. Petals yellow, oblanceolate, 2.5-4 × 0.9-1.5 mm, base attenuate, apex obtuse. Filaments 1-2.5 mm; anthers oblong, 0.5-0.7 mm. Fruit black or dark brown when mature, oblong-oblanceolate, elliptic-obovate, or rarely oblong, (0.9-)1.1-2(-2.7) cm × 3-6(-10) mm, often broader above middle, glabrous or pubescent, winged all around, base cuneate, margin sometimes slightly constricted, apex subacute, rounded, or rarely subemarginate; locule 3-6(-10) mm, with a distinct midvein and inconspicuous lateral veins; apical wing 3.5-5(-7) mm wide. Seeds light brown, narrowly oblong, 2.3-3.5(-4.5) × 0.8-1 mm. Fl. Apr-Jun, fr. May-Jul. 2n = 14, 28*.

Fujian, Gansu, Guizhou, Hebei, Henan, Hubei, Jiangxi, Liaoning, Nei Mongol, Shaanxi, Shandong, Shanxi, Sichuan, Xinjiang, Xizang, Yunnan, Zhejiang [Japan, Kazakhstan, Korea, Mongolia, Pakistan, Russia, Tajikistan, Uzbekistan; SW Asia, Europe; naturalized elsewhere].

Fields, pastures, roadsides, waste places; 600-2800 m.

Isatis indigotica Fortune; I. oblongata de Candolle var. yezoensis (Ohwi) Y. L. Chang; I. tinctoria var. indigotica (Fortune) T. Y. Cheo & K. C. Kuan; I. tinctoria var. yezoensis (Ohwi) Ohwi; I. yezoensis Ohwi.