Stanleya

Annuals, perennials, shrubs, or subshrubs; (base usually woody); not scapose; glabrous or pubescent. Stems usually erect, rarely ascending, unbranched or branched. Leaves cauline and, sometimes, basal; petiolate or sessile; basal rosulate, petiolate, blade margins entire, lyrately lobed or 1- or 2-pinnatifid; cauline blade (base sometimes auriculate or amplexicaul), margins entire or dentate to pinnatifid. Racemes considerably elongated in fruit. Fruiting pedicels horizontal, divaricate, or divaricate-ascending, slender. Flowers: sepals spreading to reflexed, oblong-linear or linear, lateral pair not saccate basally; petals usually yellow or whitish, rarely white or yellow-orange, obovate, orbicular, oblong, linear, filiform, or oblanceolate, claw distinctly differentiated from blade (claw glabrous or papillose); stamens (exserted), equal; filaments not dilated basally, (often papillose basally); anthers linear, (strongly spirally coiled after dehiscence); lateral nectar glands annular, median present or absent, confluent with lateral ones. Fruits long-stipitate, linear, often torulose, terete or latiseptate; valves each with prominent midvein, glabrous; replum rounded; septum complete; ovules 22–70 per ovary; style obsolete or distinct (to 1.7 mm); stigma capitate, entire. Seeds uniseriate, plump, not winged, usually oblong, rarely ovoid; seed coat (obscurely reticulate), slightly mucilaginous when wetted; cotyledons accumbent to incumbent. x = 14.

Distribution

w, c United States.

Discussion

Species 7 (7 in the flora).

Both R. C. Rollins (1993) and N. H. Holmgren (2005b) reported n = 12 and 2n = 24 for various species of Stanleya. However, those counts, all reported previously by Rollins (1939c), are erroneous; no species of the genus has numbers deviating from n = 14 or 28.

All species of Stanleya are well-defined, and interspecific hybridization has not yet been reported. One species, S. pinnata, is a hyperaccumulator of selenium and is a good indicator for the presence of this element in soils. Poisoning of livestock results from their feeding on large quantities of plants of this species.

Selected References

Rollins, R. C. 1939c. The cruciferous genus Stanleya. Lloydia 2: 109–127.

Lower Taxa

Stanleya albescens, Stanleya bipinnata, Stanleya confertiflora, Stanleya elata, Stanleya pinnata, Stanleya tomentosa, Stanleya viridiflora

Key

1	Cauline leaves sessile, blade bases auriculate to sagittate	> 2
1	Cauline leaves petiolate, blade bases not auriculate or sagittate	> 3
2	Annuals or biennials (without caudex); racemes dense; sepals 6-12 mm; petals linear to filiform, 0.5-1.5 mm wide, margins crisped; fruiting pedicels 10-20(-26) mm.	Stanleya confertiflora
2	Perennials (with caudex); racemes loose; sepals 12-18 mm; petals narrowly oblanceolate, 1-3 mm wide, margins usually erose, rarely subentire and crisped; fruiting pedicels 4-9(-12) mm.	Stanleya viridiflora
3	Basal leaf blades: surfaces densely tomentose; fruiting pedicels 11-22 mm; petals with glabrous claws; fruits flattened.	Stanleya tomentosa
3	Basal leaf blades: surfaces usually glabrous, rarely sparsely pubescent; fruiting pedicels 3-11(-15) mm; petals with pubescent claws (except S. elata); fruits terete or subterete	> 4
4	Cauline leaf blades: margins usually entire, rarely dentate proximally	> 5
4	Cauline leaf blades: margins often pinnatisect, pinnatifid, 2-pinnatifid, lyrate-pinnatifid, or runcinate	> 6
5	Petals linear, 0.3-1 mm wide, claws glabrous; ovules 46-70 per ovary; filaments 5-13 mm; Arizona, California, s, w Nevada.	Stanleya elata
5	Petals oblanceolate to oblong, 2-3 mm wide, claws pubescent; ovules 10-38 per ovary; filaments 11-28 mm; Colorado, Kansas, Nevada, sw Texas, Utah, Wyoming.	Stanleya pinnata
6	Biennials; petals orbicular to broadly obovate, (2.5-)3-6 mm wide; fruits suberect to ascending, slightly curved inward.	Stanleya albescens
6	Perennials; petals oblanceolate or oblong, 0.8-3 mm wide; fruits usually spreading or divaricate, rarely ascending, sometimes curved downward	> 7
7	Cauline leaf blades: margins sometimes 2-pinnatifid; sepals 6.5-10 mm; petals 5-12 mm; filaments glabrous basally; gynophores 4-11 mm; fruits torulose, tortuous.	Stanleya bipinnata
7	Cauline leaf blades: margins not 2-pinnatifid; sepals 9-16 mm; petals 10-20 mm; filaments pilose basally; gynophores 7-28 mm; fruits smooth, not tortuous.	Stanleya pinnata