11.
Rorippa dubia
(Persoon) H. Hara, J. Jap. Bot. 30: 196. 1955.
Sisymbrium dubium
Persoon, Syn. Pl. 2: 199. 1806, based on
S. apetalum
Desfontaines, Tabl. École Bot., 130. 1804, not Loureiro 1790;
Nasturtium heterophyllum
Blume;
Rorippa heterophylla
(Blume) R. O. Williams;
R. indica
(Linnaeus) Hiern var.
apetala
(de Candolle) Hochreutiner
Annuals;
usually glabrous, rarely sparsely pubescent.
Stems
(simple or branched from base), erect or ascending, branched proximally and distally, (0.4-)1.5-3.3(-4.5) dm, (glabrous or sparsely pubescent proximally).
Basal leaves
not rosulate; blade margins pinnatifid.
Cauline leaves
petiolate (to 4 cm) or (distal) sessile; blade lyrate-pinnatipartite or undivided, obovate, oblong, or lanceolate, (2-)3-11(-15) cm × (5-)10-30(-50) mm, (lateral lobes smaller than terminal), base auriculate or not, margins entire, irregularly crenate, or serrate (entire or serrulate distally).
Racemes
elongated.
Fruiting pedicels
divaricate, straight, (2-)3-8(-10) mm.
Flowers:
sepals erect, oblong-linear, (2-)2.5-3 × 0.5-0.7 mm; petals (usually absent), yellow, linear or narrowly oblanceolate, 1-1.5 × 0.2-0.7 mm, (shorter than sepals); median filaments 1.5-2.8 mm; anthers oblong, 0.5-0.8 mm.
Fruits
siliques, straight, linear, (15-)25-40 × 0.7-0.9(-1) mm; ovules 70-90 per ovary; style 0.2-1(-1.5) mm, (stout, as thick as fruit).
Seeds
uniseriate, reddish brown, ovate-orbicular, 0.5-0.8 mm (0.4-0.6 mm diam.), foveolate.
2
n
= 32, 48.
Flowering often year-round. Waste areas, slopes, roadsides, wet grounds, grassy places, field margins; 0-500[-3700] m; introduced; La., Miss., Oreg.; se Asia; introduced also in Central America, South America.
Rorippa dubia
was treated by R. L. Stuckey (1972) as
R. heterophylla
and by R. C. Rollins (1993) as
R. indica
var.
apetala
. Both authors overlooked H. Hara's (1955b) comprehensive account of its typification and that of
R. indica
.
