Tower Rockcress

Annual or biennial, 30-120 cm tall, simple, erect, glabrous, ± glaucous, sometimes turning violaceous in appearance. Rosette leaves 5-15 cm long, 1.5-3.5 cm broad, entire or toothed, stalked to subsessile, ± hairy with branched hairs rarely glabrous; cauline leaves 2-8 cm long, 0.5-3 cm broad, oblong ovate, sagittate-amplexicaul, entire, acute, subapressed, glaucous, glabrous, rarely margin sparsely hairy. Racemes many flowered, up to 30 cm long in fruit. Flowers c. 5 mm across, pale yellow, turning whitish when dried; pedicels up to 10 mm long in fruit, erect, subappressed. Sepals 2-4 mm long. Petals 4-6 mm long, 1.5 mm broad. Stamens 3 :4 mm long. Siliquae linear somewhat terete or sub-quadrangular, 30-90 mm long, c. 1.5 mm broad, erect, straight, glabrous, often subappressed; valves with a conspicuous mid-rib; seeds many, ± biseriate, c. 0.7 mm long, ovate-orbicular; septum with deep depressions.

Herbs biennial, rarely perennial, (30-)40-120(-150) cm tall, sparsely to densely pilose basally with simple and short-stalked, forked trichomes, glabrous and glaucous above. Stems erect, simple basally, often branched above. Basal leaves rosulate, petiolate; leaf blade spatulate, oblanceolate, or oblong, (4-)5-12(-15) × 1-3 cm, pubescent or rarely glabrous, margin pinnatifid, sinuate, dentate, repand, or rarely entire, apex obtuse. Cauline leaves sessile, lanceolate, oblong-elliptic, or ovate, 2-9(-12) × (0.5-)1-2.5(-3.5) cm, base sagittate or auriculate, margin dentate or entire, apex acute. Fruiting pedicels erect, (0.6-)0.7-1.6(-2) cm, slender, appressed to rachis, glabrous. Sepals oblong or oblong-linear, (2.5-)3-5 × 0.5-1.2 mm, glabrous. Petals pale yellow, creamy white, or rarely pink, linear-oblanceolate, narrowly spatulate, or rarely linear, 5-8.5 × 1.3-1.7 mm. Filaments slender, lateral pair 2.5-4.5 mm, median pairs 3.5-6.5 mm; anthers narrowly oblong, 0.7-1.5 mm. Fruit linear, (3-)4-9(-10) cm × 0.7-1.5 mm, erect, appressed to rachis, subterete-quadrangular; style 0.5-0.8(-1) mm. Seeds brown, oblong or suborbicular, 0.6-1.2 × 0.5-0.9 mm. Fl. Apr-Jul, fr. May-Aug. 2n = 12, 16, 32.

Distribution: Europe and Temperate Asia, introduced elsewhere.

Jiangsu, Liaoning, Shandong, Xinjiang, Zhejiang [Afghanistan, India, Japan, Kashmir, Kazakhstan, Korea, Kyrgyzstan, Mongolia, Nepal, Pakistan, Russia, Tajikistan, Turkmenistan, Uzbekistan; N Africa, SW Asia, Europe, North America; naturalized in Australia].

Fl. Per.: May-August.

Mountain slopes, forest margins, valleys, fields, meadows, woods, fields, river banks, roadsides; 100-3500 m.

Arabis glabra (Linnaeus) Bernhardi; A. perfoliata Lamarck; A. pseudoturritis Boissier & Heldreich; Turritis glabra var. lilacina O. E. Schulz; T. pseudoturritis (Boissier & Heldreich) Velenovsky.