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woad

Habit Biennials [annuals, perennials]; not scapose; (often glaucous), glabrous or pubescent.
Stems

erect, often unbranched basally, paniculately branched distally.

Leaves

basal and cauline;

petiolate or sessile;

basal rosulate [or not rosulate], petiolate [rarely sessile], blade margins entire, repand, or dentate [rarely pinnately lobed];

cauline blade (base auriculate, sagittate, [or amplexicaul, rarely attenuate]), margins entire [dentate].

Racemes

(corymbose, in panicles, several-flowered), considerably elongated in fruit.

Flowers

sepals erect or ascending, oblong [ovate];

petals oblanceolate [obovate, spatulate, or oblong], (equal to or longer than sepals), claw absent, (apex obtuse [subemarginate]);

stamens slightly tetradynamous;

filaments not dilated basally;

anthers oblong [ovate], (apex obtuse or apiculate);

nectar glands (6) confluent, or (4) lateral and median.

Fruiting pedicels

reflexed, slender, (filiform, often thickened and clavate apically).

Fruits

siliques or silicles (samaroid), sessile, oblong, oblanceolate, elliptic, or obovate [ovate, cordate, spatulate, orbicular], 1- (or 2-)seeded, smooth, strongly angustiseptate, (prominently winged all around or distally; seed-bearing locule papery or corky, distinctly or obscurely 1–3-veined, sometimes keeled or shortly winged), glabrous or pubescent;

valves and replum united;

septum absent;

ovules 1 (or 2) per ovary, (subapical);

stigma capitate.

Seeds

plump, not winged, narrowly oblong;

seed coat (smooth), not mucilaginous when wetted;

cotyledons incumbent or accumbent.

Isatis

Distribution
from USDA
Europe; c Asia; sw Asia; n Africa [Introduced in North America; introduced also in South America (Chile, Peru)]
[BONAP county map]
Discussion

Species 50 (1 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 7, p. 567. Author: Ihsan A. Al-Shehbaz.
Parent taxa Brassicaceae > tribe Isatideae
Subordinate taxa
I. tinctoria
Name authority Linnaeus: Sp. Pl. 2: 670. (1753): Gen. Pl. ed. 5, 301. (1754)
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