Isatis is a genus of flowering plants in the family Brassicaceae, native to the Mediterranean region east to central Asia. The genus includes woad (Isatis tinctoria). Due to their extremely variable morphology, the Asian species in particular are difficult to determine; the only reliable diagnostic feature is the ripe fruit. They are (usually) biennial or perennial herbaceous plants, often bluish and hairless or downy hairy with the upright stem branched.[2]
They are annual, biennial or perennial, branched herbs, usually glabrous and glaucous except silique. Basal leaves generally elliptic-oblong, sessile; sessile caulinary, rounded to oval-oblong.
The hermaphrodite flowers are fourfold double perianth. The four sepals are ascending to upright. The four yellow to off-white or lilac-white petals are at least as long as the sepals. They have six stamens with very small, egg-shaped or elongated-round anthers. There are nectar glands. Racemose is branched or paniculated, ebracted, inflorescence, often reaching lax and elongated in the fruit.
The fruit is a generally linear silique, oblong-cuneate to suborbicular, indehiscent, flattened laterally, unilocular, little to conspicuously winged, glabrous or with tiny hairs.[3]