is becoming common in this state and others. I first found it in Florida. The plant is easy to ID in the field because of the much divided leaves, densely pubescent stems, and ascending long fruits.
, a native species, looks similar but has shorter fruits, glandular pubescent stems, and leaves which are slightly less divided.
Photographs taken off Highway 9, Platte County, MO., 5-2-00.
This plant can be weedy or invasive according to the authoritative sources noted below.This plant may be known by one or more common names in different places, and some are listed above. Click on an acronym to view each weed list, or click here for a composite list of
Weeds of the U.S.
(Linnaeus) Webb ex Prantl in H. G. A. Engler and K. Prantl, Nat. Pflanzenfam. 55(III,2): 192. 1891.
Flixweed, tansy mustard
Linnaeus, Sp. Pl. 2: 659. 1753;
eglandular; sparsely to densely pubescent, sometimes glabrous distally, trichomes dendritic.
erect, un-branched or branched distally, (1-)2-7(-10) dm.
petiole 0.1-2(-3) cm; blade 2- or 3-pinnate, ovate or oblong to obovate in outline, to 15 cm, lateral lobes linear or oblong, (to 10 × 2 mm), margins entire.
sessile or shortly petiolate; blade smaller distally, distal lobes often narrower, surfaces often glabrous.
considerably elongated in fruit.
divaricate to ascending, straight, (5-) 8-15(-20) mm.
sepals erect to ascending, yellowish, oblong, 1.8-2.8 mm, glabrate to sparsely pubescent; petals narrowly oblanceolate, 2-3 × 0.4-0.6 mm; median filaments 2-3 mm; anthers 0.3-0.4 mm.
divaricate-ascending to erect, narrowly linear, torulose, (12-)15-27(-30) × 0.5-0.8(-1) mm, (straight or curved upward); valves each with distinct midvein; septum with a broad central longitudinal band appearing as 2 or 3 veins; ovules 20-48 per ovary; style obsolete, 0.05-0.2 mm, glabrous.
uniseriate, reddish brown, oblong, 0.7-1.3 × 0.3-0.6 mm.
Deviant chromosome counts (e.g., 2
= 12, 14, 20, 38; see R. C. Rollins 1993, N. H. Holmgren 2005b, S. I. Warwick and I. A. Al-Shehbaz 2006) are most certainly erroneous, and the species appears to be exclusively tetraploid based on
SELECTED REFERENCE Best, K. F. 1977. The biology of Canadian weeds. 22.
(L.) Webb. Canad. J. Pl. Sci. 57: 499-507.
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