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Walker's evening-primrose, Walker's sun-cup

Habit Herbs annual or short-lived perennial, villous, usually densely so proximally, less dense to glabrate distally, sometimes hairs somewhat appressed and shorter on leaves, also sometimes glandular puberulent on distal parts. Herbs annual, succulent, glabrous, glandular puberulent, or villous proximally.
Stems

slender, unbranched or branched from base, 10–60 cm.

unbranched or branched from base, 3–30 cm.

Leaves

in basal rosette and/or cauline, often purple-dotted, 2–22 × 0.4–3.5 cm;

petiole 0.4–8 cm;

blade pinnately lobed, sometimes lateral lobes greatly reduced or absent and blade reduced to terminal lobe only, terminal lobe oblong or cordate to ovate, 1–5 × 0.5–3.2 cm, margins serrate, brown oil cells prominently lining veins abaxially.

primarily in basal rosette and also cauline;

petiole 0.5–8 cm;

blade usually not pinnately lobed or, if so, then lateral lobes greatly reduced, terminal lobe oblanceolate to cordate, 0.8–7.5 × 0.4–3 cm, margins entire or sparsely denticulate, pale brown oil cells lining veins abaxially.

Racemes

erect, elongating after anthesis.

nodding, elongating after anthesis.

Flowers

opening at sunrise;

buds individually reflexed, with apical free tips less than 1 mm;

floral tube 0.5–1.5 mm, glabrous or sparsely villous inside;

sepals 1.5–5 mm;

petals bright yellow, fading pale orange or lavender, 1–6 mm;

stamens unequal, filaments of antisepalous stamens 1–3 mm, those of antipetalous ones 0.3–2 mm, anthers 0.5–2 mm, glabrous or sparsely ciliate;

style 1.5–6 mm, stigma surrounded by anthers at anthesis.

opening at sunrise;

buds without subapical free tips;

floral tube 2–4.5 mm, villous inside proximally;

sepals 3–8 mm;

petals bright yellow, with red dots near base, fading pale yellow or yellowish orange, 5.5–9 mm;

stamens unequal, filaments of antisepalous stamens 3–8 mm, those of antipetalous ones 2.8–5.5 mm, anthers 2–4 mm, ciliate;

style 10–17 mm, stigma exserted beyond anthers at anthesis.

Capsules

spreading or ascending, oblong-cylindrical, 11–45 mm;

pedicel 5–30 mm.

erect, spreading, or slightly reflexed, clavate, 18–40 mm;

pedicel 4–28 mm.

Seeds

0.6–1.2 mm.

1.2–1.7 mm.

2n

= 14.

Chylismia walkeri

Chylismia eastwoodiae

Phenology Flowering Apr–Jun.
Habitat Clay flats, on gray, alkaline, marine-deposited gumbo, sandy draws.
Elevation 1200–1800 m. (3900–5900 ft.)
Distribution
sw United States
[WildflowerSearch map]
[BONAP county map]
from FNA
CO; UT
[BONAP county map]
Discussion

Subspecies 2 (2 in the flora).

P. H. Raven (1962, 1969) determined this species to be self-incompatible and primarily autogamous.

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

Chylismia eastwoodiae is known from Mesa County, Colorado, and from Emery County south to San Juan County, Utah. P. H. Raven (1962, 1969) suspected this species to be self-incompatible, but did not have data to make the determination.

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

Key
1. Leaves primarily cauline, rarely forming inconspicuous basal rosette, lateral lobes usually greatly reduced or absent; petals 1–3 mm; anthers 0.5–0.8 mm.
subsp. walkeri
1. Leaves primarily basal, forming conspicuous rosette, cauline reduced or absent, lateral lobes usually well developed; petals 2.8–6 mm; anthers 1–2 mm.
subsp. tortilis
Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Onagreae > Chylismia > sect. Chylismia Onagraceae > subfam. Onagroideae > tribe Onagreae > Chylismia > sect. Chylismia
Sibling taxa
C. arenaria, C. atwoodii, C. brevipes, C. cardiophylla, C. claviformis, C. confertiflora, C. eastwoodiae, C. exilis, C. heterochroma, C. megalantha, C. multijuga, C. munzii, C. parryi, C. scapoidea, C. specicola
C. arenaria, C. atwoodii, C. brevipes, C. cardiophylla, C. claviformis, C. confertiflora, C. exilis, C. heterochroma, C. megalantha, C. multijuga, C. munzii, C. parryi, C. scapoidea, C. specicola, C. walkeri
Subordinate taxa
C. walkeri subsp. tortilis, C. walkeri subsp. walkeri
Synonyms Camissonia walkeri, Oenothera walkeri Oenothera scapoidea var. eastwoodiae, Camissonia eastwoodiae, O. eastwoodiae
Name authority A. Nelson: Bot. Gaz. 56: 66. (1913) — (as Chylisma) (Munz) W. L. Wagner & Hoch: Syst. Bot. Monogr. 83: 207. (2007)
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