1. Tetracme quadricornis (Stephan) Bunge, Delect. Seminum Hort. Bot. Dorpat. 1836: 7. 1836.
四齿芥 si chi jie
Erysimum quadricorne Stephan in Willdenow, Sp. Pl. 3: 514. 1800; Notoceras quadricornis (Stephan) de Candolle; Tetracme elongata Kitamura; T. quadricornis var. longicornis Regel.
Herbs (3-)5-20(-25) cm tall, tomentose throughout. Stems ascending, branched at or near base. Basal and lowermost cauline leaves with petioles 2-6(-10) mm; leaf blade oblong-linear or narrowly oblanceolate, (1-)2-5 cm × (1-)2-6(-8) mm, base attenuate, margin entire or rarely repand-dentate, apex obtuse. Upper cauline leaves similar to basal, smaller, subsessile, entire. Fruiting pedicels 1-1.5 mm, subclavate, stout, about as wide as fruit base, appressed to rachis. Sepals ovate, 0.7-0.9(-1) mm, distally white and petaloid. Petals white, narrowly oblanceolate, 0.5-0.8(-0.9) × 0.2-0.3 mm, not clawed. Filaments white, 0.4-0.6 mm; anthers ovate, 0.2-0.3 mm. Ovules 8-14 per ovary. Fruit linear, 5-8 × 0.7-1 mm, compressed, torulose, base appressed to rachis, distal half arcuate or recurved; valves tomentose, with stellate trichomes mixed with fewer, much larger, subsetose simple ones to 1.5 mm, apex not extended beyond horns; subapical horns 0.5-1.8(-2.2) mm, erect or divaricate-ascending, straight; style absent. Seeds yellow or light brown, oblong, 0.7-0.9 × 0.4-0.6 mm. Fl. and fr. May-Jun.
Deserts, sand dunes, field margins, roadsides, disturbed areas; 300-3800 m. Xinjiang [Afghanistan, Kazakhstan, Kyrgyzstan, Mongolia, Tajikistan, Turkmenistan, Uzbekistan].
The record of Tetracme contorta Boissier in FRPS is based on misidentified plants of T. quadricornis. True T. contorta is endemic to W Pakistan and adjacent Afghanistan and has petals 2-3 mm, very lax infructescences, and fruit without subsetose, simple trichomes.