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Eureka dunes evening primrose

California evening primrose

Habit Herbs perennial, densely strigillose and villous; with deep-seated, fleshy underground parts from underground horizontal rootstocks. Herbs perennial, densely strigillose, sometimes also villous, or glabrous; from a taproot, lateral roots producing adventitious shoots, or rarely with fleshy underground horizontal rootstock (subsp. eurekensis).
Stems

sprawling to decumbent, sometimes new rosettes forming at stem apex when becoming buried in drifting sand, 15–60 cm.

ascending or decumbent, usually branched from near base, sometimes new rosettes forming at branch apex when buried in drifting sand, 10–60 cm.

Leaves

blade rhombic-ovate to oblanceolate, margins entire or weakly dentate.

in a basal rosette and cauline, rosette sometimes weakly developed or absent, at least during flowering, 1–13 × 0.5–2 cm;

petiole 0–2(–4.5) cm;

blade oblong to oblanceolate or spatulate, sometimes rhombic-ovate, margins entire or weakly to conspicuously dentate or pinnatifid.

Flowers

floral tube 25–30 mm;

sepals 15–25 mm;

petals 20–30 mm.

1–several opening per day near sunset;

buds nodding, weakly quadrangular, with free tips 0–0.8 mm;

floral tube 20–40 mm;

sepals 15–30 mm, not spotted;

petals white, fading pink to deep pink, broadly obcordate, 15–35(–40) mm;

filaments 10–17 mm, anthers 5–10 mm;

style 30–60 mm, stigma exserted beyond anthers at anthesis.

Capsules

30–70 mm.

spreading to ascending, woody in age, often curved upward, cylindrical, obtusely 4-angled, tapering slightly from base to apex, 20–80 × 2–3.5 mm;

sessile.

Seeds

numerous, in 1 row per locule, olive-brown or yellowish brown to black, sometimes with minute purple dots, obovoid, 1–2.5 mm.

2n

= 14.

Oenothera californica subsp. eurekensis

Oenothera californica

Phenology Flowering (Mar)Jun–Jul(Sep).
Habitat Sand dunes.
Elevation 900–1200 m. (3000–3900 ft.)
Distribution
from FNA
CA
[BONAP county map]
from USDA
w United States; nw Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

Subspecies eurekensis is known from three main areas within the Eureka Dunes system, Inyo County. It is federally listed as endangered and is in the Center for Plant Conservation’s National Collection of Endangered Plants.

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

Subspecies 3 (3 in the flora).

Most populations of Oenothera californica are self-incompatible (W. L. Wagner et al. 2007; K. E. Theiss et al. 2010), but some populations of subsp. californica are self-compatible. All chromosome counts indicate that subspp. avita and eurekensis are diploid (2n = 14) and those of subsp. californica are tetraploid (2n = 28). Oenothera californica is polymorphic with subspp. avita and californica being very similar, and differing primarily in ecology, distribution, and relatively minor differences in leaf morphology and ploidy level, while the sand dune-restricted subsp. eurekensis is more distinctive in both morphology and habitat.

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

Key
1. Plants with fleshy underground horizontal rootstocks; stems sometimes with new rosettes forming at stem apex when becoming buried in drifting sand; leaf blades rhombic-ovate to oblanceolate, margins entire or weakly dentate.
subsp. eurekensis
1. Plants with a taproot and adventitious shoots from lateral roots; stems not with new rosettes forming at branch apex; leaf blades oblong to oblanceolate to spatulate, margins entire or weakly to conspicuously dentate or pinnatifid.
→ 2
2. Leaf blade margins usually entire or weakly dentate, sometimes more conspicuously dentate to pinnatifid; capsules 30–55 mm.
subsp. californica
2. Leaf blade margins conspicuously dentate to pinnatifid, rarely some or all of them entire or weakly dentate; capsules 20–80 mm.
subsp. avita
Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Anogra > Oenothera californica Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Anogra
Sibling taxa
O. californica subsp. avita, O. californica subsp. californica
O. acutissima, O. albicaulis, O. argillicola, O. arida, O. arizonica, O. biennis, O. boquillensis, O. brachycarpa, O. calcicola, O. canescens, O. capillifolia, O. cavernae, O. cespitosa, O. cinerea, O. clelandii, O. coloradensis, O. cordata, O. coronopifolia, O. coryi, O. curtiflora, O. curtissii, O. deltoides, O. demareei, O. dodgeniana, O. drummondii, O. elata, O. engelmannii, O. falfurriae, O. filiformis, O. filipes, O. flava, O. fruticosa, O. gaura, O. gayleana, O. glaucifolia, O. glazioviana, O. grandiflora, O. grandis, O. harringtonii, O. hartwegii, O. havardii, O. heterophylla, O. hispida, O. howardii, O. humifusa, O. jamesii, O. kunthiana, O. laciniata, O. lavandulifolia, O. lindheimeri, O. linifolia, O. longissima, O. macrocarpa, O. mckelveyae, O. mexicana, O. nealleyi, O. neomexicana, O. nutans, O. nuttallii, O. oakesiana, O. organensis, O. pallida, O. parviflora, O. patriciae, O. perennis, O. pilosella, O. platanorum, O. podocarpa, O. primiveris, O. psammophila, O. pubescens, O. rhombipetala, O. riparia, O. rosea, O. serrulata, O. sessilis, O. simulans, O. sinuosa, O. spachiana, O. speciosa, O. stricta, O. suffrutescens, O. suffulta, O. tetraptera, O. texensis, O. toumeyi, O. triangulata, O. triloba, O. tubicula, O. villosa, O. wolfii, O. xylocarpa
Subordinate taxa
O. californica subsp. avita, O. californica subsp. californica, O. californica subsp. eurekensis
Synonyms O. deltoides subsp. eurekensis, O. avita subsp. eurekensis O. albicaulis var. californica, Anogra californica, O. pallida var. californica
Name authority (Munz & J. C. Roos) W. M. Klein: Aliso 5: 179. (1962) (S. Watson) S. Watson in W. H. Brewer et al.: Bot. California 1: 223. (1876)
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