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

naked-stem beeblossom, Paiute suncup

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, strigillose, villous, or glandular puberulent.
Stems

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

usually unbranched, sometimes branched from base, 3–45 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, cauline poorly developed or absent, 1–18 × 0.5–3.5 cm;

petiole 0.5–6.5 cm;

blade pinnately lobed or lateral lobes greatly reduced or absent, sometimes mixed on same plant, terminal lobe narrowly ovate to ovate or elliptic, 1–6.5 × 0.5–3.3 cm, margins irregularly dentate to subentire, oil cells on abaxial surface inconspicuous or conspicuous, pale yellowish brown or dark brown.

Racemes

erect, elongating after anthesis.

nodding, elongating in fruit.

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 with or without subapical free tips less than 1 mm;

floral tube 1–4 mm, sparsely villous or glabrous inside;

sepals 1.2–5 mm;

petals bright yellow, often with red dots near base, fading pale yellow or yellowish orange, 1.5–5.5(–8) mm;

stamens unequal, filaments of antisepalous stamens 1.2–6 mm, those of antipetalous ones 0.5–4 mm, anthers 1–2.5 mm, ciliate or glabrous;

style 3–11 mm, stigma surrounded by anthers at anthesis.

Capsules

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

pedicel 5–30 mm.

ascending, clavate, 8–50 mm;

pedicel 4–20 mm.

Seeds

0.6–1.2 mm.

1–2 mm.

Chylismia walkeri

Chylismia scapoidea

Distribution
sw United States
[WildflowerSearch map]
[BONAP county map]
w United States
[WildflowerSearch map]
[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.)

Subspecies 4 (4 in the flora).

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

(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
1. Oil cells lining veins of leaf blades abaxially usually pale yellowish brown, inconspicuous, rarely darker; leaf blades usually unlobed, rarely pinnately lobed with few, small lateral lobes, margins subentire.
→ 2
2. Capsules (10–)15–30 mm; petals 1.7–5 mm.
subsp. scapoidea
2. Capsules 25–50 mm; petals 1.5–2 mm.
subsp. macrocarpa
1. Oil cells lining veins of leaf blades abaxially dark brown, conspicuous; leaf blades pinnately lobed, lobes well developed or with few, small lateral lobes or unlobed, margins dentate.
→ 3
3. Petals 1.8–4 mm; lateral lobes of leaves often few or absent, sometimes well developed; capsules 8–20(–28) mm.
subsp. brachycarpa
3. Petals 4–5.5(–8) mm; lateral lobes of leaves usually well developed, sometimes poorly developed; capsules 16–38 mm.
subsp. utahensis
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. eastwoodiae, C. exilis, C. heterochroma, C. megalantha, C. multijuga, C. munzii, C. parryi, C. specicola, C. walkeri
Subordinate taxa
C. walkeri subsp. tortilis, C. walkeri subsp. walkeri
C. scapoidea subsp. brachycarpa, C. scapoidea subsp. macrocarpa, C. scapoidea subsp. scapoidea, C. scapoidea subsp. utahensis
Synonyms Camissonia walkeri, Oenothera walkeri Oenothera scapoidea, Camissonia scapoidea, O. brevipes var. scapoidea
Name authority A. Nelson: Bot. Gaz. 56: 66. (1913) — (as Chylisma) (Torrey & A. Gray) Nuttall ex Raimann in H. G. A. Engler and K. Prantl: Nat. Pflanzenfam. 96[III,7]: 217. (1893)
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