Sisymbrium altissimum L.
tumbling mustard
Annual herb. Stem erect, hairy at base, to 1 m tall. Rosette and lower stem lvs sparsely hispid especially below, pinnatifid, rarely almost 2-pinnatifid, 5-15-(30) × 1.5-7-(10) cm, with 5-9-(12) pairs of toothed triangular lobes. Upper stem lvs glabrous, smaller, pinnatifid with linear-filiform segments. Racemes often flexuous, ebracteate, suberect or spreading, glabrous, 10-30 cm long. Pedicels c. 5 mm long at flowering, elongating to up to c. 10 mm long at fruiting, glabrous. Sepals glabrous, 3-4 mm long, the outer pair with short horn at apex (most conspicuous in bud). Petals yellow, 6-8 mm long. Anthers at least 1 mm long; filaments = or slightly > sepals. Silique glabrous, spreading, linear-cylindric, (40)-70-110 × 1-1.5 mm; style 0.5-1 mm long. Seeds ovoid to oblong, brown, c. 0.8 mm long.
S.: S. Canterbury (Waitaki Valley), C. Otago, Southland (Gorge Creek).
C. and E. Europe, S.W. Asia 1870
Common on roadsides and waste land.
S. altissimum is sometimes confused with Descurainea sophia but may be distinguished by its less dissected lvs with unbranched hairs only, longer petals and anthers, stouter pedicels and longer, broader siliques. S. altissimum has also been referred to as S. pannonicum and S. sinapistrum in N.Z.
