FNA: Eremothera vs. Eremothera pygmaea

Phenology

Flowering late May–Aug.

Habitat

Steep, loose slopes, in scree, on gravelly flats or washes.

Elevation

150–1500 m. (500–4900 ft.)

Distribution

w United States; sc United States; nw Mexico

[BONAP county map]

ID; OR; WA

[WildflowerSearch map]

[BONAP county map]

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).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

P. H. Raven (1969) determined Eremothera pygmaea to be self-compatible and autogamous. It is rare and local at scattered localities in eastern Washington (Douglas, Grant, and Kittitas counties), eastern Oregon (Gilliam, Grant, Harney, and Wheeler counties), and at one locality in adjacent southern Idaho (Jerome County).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

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.	E. 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.	E. 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.	E. 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.	E. 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.	E. 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.	E. pygmaea
6. Seeds monomorphic, all appearing smooth, finely reticulate; capsules 8–12 mm; leaves 0.5–3.5 × 0.5–1 cm.	E. gouldii