Herbs, annual, caulescent; with a taproot. Stems usually erect, sometimes ascending, usually well-branched from base, sometimes also distally, with white or reddish green exfoliating epidermis. Leaves cauline, proximal ones often clustered near base, alternate; stipules absent; petiolate, often subsessile distally; blade margins denticulate, crenate-dentate, serrulate, sinuate-toothed, or entire. Inflorescences spikes, erect or nodding at anthesis, or flowers also in proximal leaf-axils in some taxa. Flowers bisexual, actinomorphic, buds erect; floral-tube deciduous (with sepals, petals, and stamens) after anthesis, with basal nectary; sepals 4, reflexed singly or in pairs; petals 4, usually white, rarely red or tinged red, without spots, fading pink or red; stamens 8 in 2 unequal series, episepalous ones rarely abortive (E. minor), anthers versatile, pollen shed singly; ovary 4-locular, without apical projection, style villous near base, strigillose, or glabrous, stigma entire, subglobose, surface unknown, probably wet and non-papillate. Fruit a capsule, straight or much contorted, narrowly cylindrical throughout or thickened proximally, terete or 4-angled, regularly but tardily loculicidal; sessile. Seeds numerous, in 1 row per locule, usually monomorphic and narrowly obovoid to oblanceoloid, sometimes dimorphic, with seeds near base of capsule sharply angular and truncate-ellipsoid, finely reticulate, or seeds near base of capsule coarsely papillose. = 7.

Distribution

w, sc United States, nw Mexico

Discussion

Species 7 (7 in the flora).

Species of Eremothera are found mainly in the interior deserts and bordering areas of the western United States.

R. A. Levin et al. (2004) found strong molecular support for paraphyly in the broadly delimited Camissonia of P. H. Raven (1969). There was some support for a clade of Camissonia and Eremothera and another clade of Camissoniopsis, Neoholmgrenia, and Tetrapteron (Levin et al.), but without morphological features linking the members of these two clades. The monophyletic subclades of these two clades were recognized as genera by W. L. Wagner et al. (2007) whereas they were all treated by Raven as clearly distinguishable sections. Raven recognized four distinct groups within Eremothera (as Camissonia sect. Eremothera): E. refracta and its autogamous derivative, E. chamaenerioides; the very diverse E. boothii (with six subspecies) and two rare autogamous derivatives, E. gouldii and E. pygmaea; the local clay endemic E. nevadensis; and the widespread autogamous and often cleistogamous E. minor. Levin et al. included one species from each of these four groups in their molecular analyses and found strong support for Eremothera as circumscribed by Raven and maintained by Wagner et al. Eremothera is well defined by white petals that open in the evening and an entire, subglobose stigma; some species are visited by moths at anthesis and by bees the following morning (Raven). Reproductive features include: self-incompatible (E. boothii, E. refracta, and, possibly, E. nevadensis) or self-compatible; flowers vespertine; outcrossing and pollinated in the evening by small moths and the following morning by bees, in E. boothii subsp. decorticans by large oligolectic andrenid bees (E. G. Linsley et al. 1963, 1964, 1973), or autogamous, rarely cleistogamous (Raven).

Selected References

None.

Lower Taxa

Eremothera boothii, Eremothera chamaenerioides, Eremothera gouldii, Eremothera minor, Eremothera nevadensis, Eremothera pygmaea, Eremothera refracta

Key

1	Capsules narrowly cylindrical; stems flowering distally.	> 2
2	Sepals 4–6 mm; petals 3.5–10 mm; floral tube 4–7 mm; stigmas exserted beyond anthers at anthesis.	Eremothera refracta
2	Sepals 1.5–2.5 mm; petals 1.8–3 mm; floral tube 1.5–3 mm; stigmas surrounded by anthers at anthesis.	Eremothera chamaenerioides
1	Capsules cylindrical, proximally thickened; stems flowering distally and proximally.	> 3
3	Stigma exserted beyond anthers at anthesis; sepals (2.7–)3.2–8 mm; petals (3–)3.5–9 mm.	> 4
4	Primary stem short, lateral stems decumbent; leaves usually in a tuft distally; inflorescences erect; petals 3–5 mm; style 6–7 mm, glabrous.	Eremothera nevadensis
4	Stems usually well branched at base and distally; leaves well distributed or basally clustered; inflorescences nodding; petals (3–)3.5–9 mm; style (6.5–)8.2–13.5(–15) mm, proximally villous.	Eremothera boothii
3	Stigma surrounded by anthers at anthesis; sepals 0.8–2.6 mm; petals 0.8–2.5 mm.	> 5
5	Stems flowering from base; herbs densely strigillose, often also glandular puberulent in inflorescences.	Eremothera minor
5	Stems usually not flowering near base; herbs glandular puberulent, usually also villous.	> 6
6	Seeds dimorphic, basal ones coarsely papillose; capsules 8–20 mm; leaves 1.5–6.5 × 0.5–2 cm.	Eremothera pygmaea
6	Seeds monomorphic, all appearing smooth, finely reticulate; capsules 8–12 mm; leaves 0.5–3.5 × 0.5–1 cm.	Eremothera gouldii