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

beeblossom, browneyes

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,usually annual, sometimes perennial, rarely biennial, usually caulescent.
Stems

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

ascending to erect, usually branched.

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.

basal and cauline, cauline often reduced, basal often forming well-developed rosette, alternate;

stipules absent; long-petiolate;

blade often pinnately (rarely bipinnately) lobed, sometimes unlobed, or lateral lobes greatly reduced or absent, terminal lobe usually large, margins usually regularly or irregularly dentate to serrate, sometimes denticulate, serrulate, or entire, abaxial surface or margin with ± conspicuous, usually brown, oil cells.

Racemes

erect, elongating after anthesis.

Inflorescences

racemes, erect or nodding.

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.

bisexual, actinomorphic, buds usually erect, sometimes reflexed;

floral tube deciduous (with sepals, petals, and stamens after anthesis), with basal nectary;

sepals 4, reflexed singly;

petals 4, usually yellow or white, often fading orange-red, sometimes lavender or purple, rarely cream, often with 1+ red dots near base;

stamens usually 8, in 2 subequal series, rarely 4 in 1 series (usually in C. exilis), anthers versatile, pollen shed singly or in tetrads;

ovary 4-locular, stigma usually entire and capitate, rarely conical-peltate and ± 4-lobed, surface unknown, probably wet and non-papillate.

Fruit

a capsule, straight or slightly curved, subterete and clavate or oblong-cylindrical, regularly loculicidal; pedicellate.

Capsules

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

pedicel 5–30 mm.

Seeds

0.6–1.2 mm.

numerous, in 2 rows per locule, lenticular to narrowly ovoid to narrowly obovoid, finely pitted, with ± pronounced membranous margin when immature.

xI> = 7.

Chylismia walkeri

Chylismia

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

Species 16 (16 in the flora).

Chylismia is distinguished from other genera formerly included in Camissonia by straight to arcuate (never twisted or curled) capsules on distinct pedicels and seeds in 2 rows per locule. R. A. Levin et al. (2004) included only one species each from Camissonia sects. Chylismia and Lignothera; the two formed a moderately supported branch, which led W. L. Wagner et al. (2007) to recognize Chylismia as a distinct genus. Chylismia is strongly supported in a sister relationship to the realigned Oenothera. This clade is in turn sister to Eulobus. Reproductive features include: self-incompatible (C. brevipes, C. claviformis, C. multijuga, C. munzii, and probably C. confertiflora, C. eastwoodiae, and C. parryi; P. H. Raven 1962, 1969) or self-compatible; flowers diurnal, outcrossing and pollinated by mostly oligolectic bees or autogamous, or opening one to two hours before sunset (in one subspecies of C. claviformis and the two species of sect. Lignothera); the evening-opening subspecies of C. claviformis pollinated mostly by oligolectic bees and moths, C. cardiophylla mainly by small moths, and C. arenaria, with its long floral tubes, by hawkmoths (E. G. Linsley et al. 1963, 1963b, 1964). Most species are diploid (2n = 14) but there are occasional tetraploids (2n = 28); floating translocations are relatively common (Raven 1962, 1969).

(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. Floral tubes 0.4–9 mm; pollen shed singly; leaves basal and cauline, usually with well-developed basal rosettes, blades usually pinnately or bipinnately lobed, lateral lobes sometimes greatly reduced or absent; plants usually annual, sometimes perennial, rarely biennial.
sect. Chylismia
1. Floral tubes 4.5–40 mm; pollen shed in tetrads; leaves cauline, blades unlobed; plants usually perennial, sometimes annual.
sect. Lignothera
Source FNA vol. 10. FNA vol. 10. Author: Warren L. Wagner.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Onagreae > Chylismia > sect. Chylismia Onagraceae > subfam. Onagroideae > tribe Onagreae
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
Subordinate taxa
C. walkeri subsp. tortilis, C. walkeri subsp. walkeri
C. sect. Chylismia, C. sect. Lignothera
Synonyms Camissonia walkeri, Oenothera walkeri Oenothera, Camissonia section chylismia, Oenothera section chylismia, Oenothera subg. chylismia
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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