16.
Lepidium flavum
Torrey in War Department [U.S.], Pacif. Railr. Rep. 4(5): 67. 1857.
Lepidium flavum
var.
apterum
Henrard;
L. flavum
var.
felipense
C. L. Hitchcock;
Nasturtium flavum
(Torrey) Kuntze;
Sprengeria flava
(Torrey) Greene;
S. minuscula
Greene;
S. watsoniana
Greene
Annuals;
glabrous.
Stems
few to several from base, prostrate or decumbent, branched, (0.2-)0.4-3(-4.6) dm.
Basal leaves
rosulate; petiole (0.3-)0.6-2.5(-3.2) cm; blade spatulate to oblanceolate or linear, pinnatifid or lobed (lobes 3-9 pairs, ovate to oblong), (0.7-)1.3-5.2(-6) cm × 3-8 mm, margins (of lobes) entire.
Cauline leaves
: petioles 0.1-0.5 cm; blade obovate to spatulate or oblanceolate, (0.6-) 1-1.8(-2.3) cm × 2-8(-14) mm, base attenuate-cuneate, not auriculate, margins dentate-sinuate to crenate or entire.
Racemes
(corymbose to subcapitate), slightly elongated in fruit; rachis glabrous.
Fruiting pedicels
divaricate to horizontal, straight or slightly sigmoid, (terete), (2.7-)3-4.4(-5) × 0.2-0.3 mm, glabrous.
Flowers:
sepals obovate-oblong, 1-2 × 0.6-1 mm; petals yellow (rarely creamy white at early anthesis), spatulate, (1.8-)2-2.8(-3) × 0.6-1 mm, claw 0.5-1 mm; stamens 6; filaments (median pairs) 1.2-2 mm, (glabrous); anthers 0.4-0.5 mm.
Fruits
usually narrowly to broadly ovate, rarely suborbicular, (2.2-)2.5-3.8(-4.2) × (1.6-)2.2 3.2(-3.5) mm, apically divergently winged, apical notch 0.2-0.6 mm deep; valves thin, smooth, moderately reticulate-veined, usually glabrous, rarely pubescent; style 0.7-1.6 mm, exserted beyond apical notch.
Seeds
ovate, 1-1.6 × 0.6-0.9 mm.
2
n
= 32.
Flowering Mar-Jun. Sagebrush communities, open mesas, sandy flats and deserts, alluvial fans, dry valley floors, floodplains, washes, alkaline flats, roadsides, playa margins; 600-1600 m; Calif., Nev.; Mexico (Baja California).
The slightly smaller-fruited form of
Lepidium flavum
, recognized by C. L. Hitchcock (1936) and R. C. Rollins (1993) as var.
felipense
, does not merit recognition.
