Flora of North America species comparison

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Oenothera glaucifolia

Oenothera sect. Gaura

false gaura

biennial bee-blossom
Habit Herbs probably biennial, glabrous, becoming sparsely to densely glandular puberulent and short-villous distally, glaucous at least in proximal parts; from stout roots. Herbs annual, biennial, or perennial, caulescent; from a taproot, sometimes woody or producing rhizomes.
Stems

erect, branched or unbranched, 30–300 cm.

usually erect or ascending, sometimes decumbent, branched or unbranched.
Leaves

in a basal rosette and cauline, basal 3–7 × 0.5–2 cm, sessile, blade oblong to oblong-lanceolate, base usually ± auriculate, margins entire;

cauline 3–8(–10) × 0.4–1.8 cm, blade lanceolate to oblong-lanceolate, gradually smaller, becoming linear-subulate distally.

in a basal rosette and cauline (sometimes not present at flowering), (0.5–)2–8(–13) cm;

blade margins sinuate-dentate to denticulate, serrate, lobed, or entire.
Inflorescences

long, wandlike, unbranched or branched.

solitary flowers in axils of distal leaves, forming a spike, erect or nodding.
Flowers

4-merous, nearly actinomorphic, opening near sunrise;

floral tube 6–17 mm;

sepals 4–6 mm;

petals white, fading off-white or tinged pink, slightly unequal, rhombic, 4–6 mm, abruptly clawed;

filaments 5–8 mm, anthers 1.5–2 mm, pollen 85–100% fertile;

style 6–10, stigma exserted beyond anthers at anthesis.

opening near sunset or sunrise;

buds erect, terete, without free tips;

floral tube 1.5–20[–42] mm, usually lanate in distal 1/2 within;

sepals splitting along one suture, remaining coherent and reflexed as a unit at anthesis, or separating in pairs or sometimes individually;

petals white [rarely yellow], fading pink to red, purple, or off-white, spatulate to elliptic, rhombic, or, sometimes, oblanceolate, usually clawed;

filaments with basal scale 0.3–0.5 mm, these nearly closing mouth of floral tube, or sometimes reduced or absent;

stigma deeply divided into (3 or) 4 linear lobes.
Capsules

ovoid, 4-angled, somewhat flattened, 3–4 × 1.5–2.3 mm, valves with raised midrib and conspicuous lateral veins;

sessile.

woody and nutlike, ovoid, fusiform, lanceoloid, ellipsoid, obovoid, or pyramidal, (3- or)4-angled, sometimes weakly so, or (3- or)4-winged, apex acute to attenuate or, sometimes, rounded, indehiscent, septa fragile, not evident at maturity;

sessile, sometimes disarticulating from plant at maturity.
Seeds

1, pale yellow, oblanceoloid, 2.4–2.6 × 1–1.5 mm.

reduced to 1–4(–8), usually ovoid, rarely oblanceoloid (O. glaucifolia), surface smooth.
2n

= 14.

= 14, 28, 42, 56.

Oenothera glaucifolia

Oenothera sect. Gaura
Phenology Flowering May–Oct(–Nov).
Habitat Rocky prairie slopes and outcrops or bluffs, along streams, roadsides, usuallyon limestone.
Elevation 200–1300 m. (700–4300 ft.)
Distribution
from FNA
AR; CO; KS; MO; NE; NM; OK; TX; WY
[WildflowerSearch map]
[BONAP county map]
North America; Mexico; Central America (Guatemala) [Introduced in South America, Europe, Asia, s Africa, Australia]
[BONAP county map]
Discussion

Oenothera glaucifolia is self-incompatible, the flowers diurnal, pollinated primarily by wasps (R. Clinebell, unpubl.), as well as bees, flies, butterflies, and occasionally beetles (summarized by W. L. Wagner et al. 2007). It was collected once in 1988 in Indiana at Miller Woods Visitor Center (Lake County), Dritz 596 (MOR); it seems likely that it was introduced, and has not been collected there since.

Stenosiphon virgatus Spach is a superfluous name and pertains here.

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

Species 25 (23 in the flora).

Section Gaura consists of 25 species (26 taxa) that are subdivided into eight subsections [seven in the flora area; subsect. Gauridium (Spach) W. L. Wagner & Hoch is is found only in Mexico]. All species have indehiscent capsules, a feature otherwise found in Oenothera only in O. canescens (sect. Gauropsis). Oenothera havardii (sect. Paradoxus) and O. linifolia (sect. Peniophyllum) have tardily and only partially dehiscent capsules. Twenty-one species in four subsections (Campogaura, Gaura, Stipogaura, and Xenogaura) have zygomorphic flowers; the other four subsections (Gauridium, Schizocarya, Stenosiphon, and Xerogaura), each with a single species, have actinomorphic, or nearly actinomorphic, flowers. Since Linnaeus described Gaura, it has been maintained as distinct at the generic level and, at various times, even at the tribal level. Its distinct status rested on several characteristic features including a scale at the base of the filaments; a peltate indusium at the base of the stigma; indehiscent, nutlike capsules; and seeds reduced to 1–4(–8) (P. H. Raven and D. P. Gregory 1972[1973]; W. L. Wagner et al. 2007). The most recent molecular studies (G. D. Hoggard et al. 2004; R. A. Levin et al. 2004) place Gaura strongly within the Oenothera clade and equally strongly in a clade with other sections possessing winged/angled capsules that are sometimes indehiscent or nearly so. Hoggard et al. found strong support for the inclusion of the monotypic Stenosiphon within Gaura; Levin et al. concurred, finding strong support for the monophyly of the Gaura lineage, but placed it unequivocally within Oenothera. Reconsidering the distinctive features of Gaura, Wagner et al. found that the indusium characterizes the whole genus Oenothera, and the indehiscent fruits seem to characterize a larger clade in the genus. The reduction in seed number appears to be a strong synapomorphy for the reconstituted Oenothera sect. Gaura. Wagner et al. recognized eight subsections within sect. Gaura that also includes Stenosiphon. The subsections are arranged according to the synthesis of morphological characters, crossing analyses, and molecular data (Raven and Gregory; Wagner et al.). Oenothera anomala Curtis and O. hexandra (Ortega) W. L. Wagner & Hoch are Mexican species that occur well south of the flora area.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Filaments without basal scales or with minute scale; flowers nearly actinomorphic.
→ 2
2. Floral tubes 6–17 mm; herbs probably biennial, glaucous at least in proximal part 17k.
O. subsect. Stenosiphon
2. Floral tubes 1.5–5 mm; herbs annual, not glaucous 17k.
O. subsect. Schizocarya
1. Filaments with basal scales; flowers zygomorphic or sometimes nearly actinomorphic.
→ 3
3. Capsules with a slender stipe (0.5–)2–10 mm 17k.
O. subsect. Stipogaura
3. Capsules usually with a stipe 0.2–2.2 mm.
→ 4
4. Capsules pyramidal in distal 1/2, abruptly constricted to a cylindrical proximal part.
→ 5
5. Capsules not conspicuously bulging at base of distal pyramidal 1/2; plants not rhizomatous 17k.
O. subsect. Campogaura
5. Capsule conspicuously bulging at base of the distal pyramidal 1/2; plants rhizomatous 17k.
O. subsect. Xenogaura
4. Capsules fusiform, ellipsoid, ovoid, or obovoid and then abruptly constricted or cuneate to base.
→ 6
6. Capsules ellipsoid, ovoid, or obovoid 17k.
O. subsect. Gaura
6. Capsules fusiform.
→ 7
7. Floral tubes 9–13 mm; flowers nearly actinomorphic 17k.
O. subsect. Xerogaura
7. Floral tubes 3–11(–13) mm; flowers zygomorphic 17k.
O. subsect. Campogaura
Source FNA vol. 10. FNA vol. 10.
Parent taxa Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera > sect. Gaura > subsect. Stenosiphon Onagraceae > subfam. Onagroideae > tribe Onagreae > Oenothera
Sibling taxa
O. acutissima, O. albicaulis, O. argillicola, O. arida, O. arizonica, O. biennis, O. boquillensis, O. brachycarpa, O. calcicola, O. californica, 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. 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. subsect. Campogaura, O. subsect. Gaura, O. subsect. Schizocarya, O. subsect. Stenosiphon, O. subsect. Stipogaura, O. subsect. Xenogaura, O. subsect. Xerogaura
Synonyms Gaura linifolia, Stenosiphon linifolius Gaura
Name authority W. L. Wagner & Hoch: Syst. Bot. Monogr. 83: 212. (2007) (Linnaeus) W. L. Wagner & Hoch: Syst. Bot. Monogr. 83: 165. (2007)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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