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Citation: Wagner WL, Krakos KN, Hoch PC (2013) Taxonomic changes in Oenothera sections Gaura and Calylophus (Onagraceae). PhytoKeys 28: 61–72. doi: 10.3897/phytokeys.28.6143
The long-recognized genus Gaura was shown recently to be deeply nested within one of two major clades of Oenothera. New molecular data indicate further taxonomic changes are necessary in Oenothera sect. Gaura. We make these changes here, including three new combinations, in advance of the Onagraceae treatment for the Flora of North America. The new phylogenetic studies show that several pairs of taxa treated as subspecies in the most recent revision by Raven and Gregory (1972) had independent origins within sect. Gaura, and are here elevated to species level (Oenothera nealleyi for Gaura suffulta subsp. nealleyi; Oenothera dodgeniana for Gaura neomexicana subsp. neomexicana; and Oenothera podocarpa for Gaura hexandra subsp. gracilis). Also, a nomenclatural problem in Oenothera sect. Calylophus is corrected by adopting the name Oenothera capillifolia Scheele for the species known previously, and nomenclaturally correct, as Calylophus berlandieri Spach. This problem necessitates a new combination Oenothera capillifolia subsp. berlandieri.
Oenothera, Gaura
The molecular studies by
Portion of a Bayesian tree of Oenothera sect. Gaura within a larger analysis of one of two major clades of Oenothera, which has been referred to as clade B by
Below we provide the nomenclature, revised descriptions, and geographic and ecological ranges for all six species of subsect. Gaura involved in these changes. We also provide a key to all 13 species of subsect. Gaura.
| 1a | Flowers 3-merous; fruits 3-angled | 2 |
| 1b | Flowers 4-merous; fruits 4-angled | 5 |
| 2a | Plants usually unbranched proximally, 60–180 cm tall; fruit narrowly ellipsoid or ellipsoid; coastal plain from Florida to North Carolina | Oenothera simulans |
| 2b | Plants usually branched proximally, 15–65 cm tall; fruits ellipsoid or ovoid | 3 |
| 3a | Sepals strigillose to subglabrous; pollen ca. 50 % fertile; north-central Texas and Oklahoma | Oenothera triangulata |
| 3b | Sepals strigillose to glandular puberulent; pollen 90–100 % fertile | 4 |
| 4a | Sepals 3–10 mm; inflorescence usually glandular puberulent; Mexico and Guatemala | Oenothera hexandra |
| 4b | Sepals 10–15 mm; inflorescence strigillose; Texas, Oklahoma, Louisiana, and Alabama | Oenothera patriciae |
| 5a | Flowers opening near sunrise; plants clumped perennial, usually branching from the base, villous throughout and usually glandular puberulent in the distal parts; southeast Texas and Louisiana | Oenothera lindheimeri |
| 5b | Flowers opening near sunset or rarely sunrise (Oenothera demareei); plants annual or biennial, branched or unbranched; villous, strigillose or short-hirtellous throughout, distal parts usually glandular puberulent, short-hirtellous, strigillose, or subglabrous, occasionally villous | 6 |
| 6a | Fruits angled but not winged; plants (5–)100–400 cm tall | 7 |
| 6b | Fruits broadly winged on the angles and deeply furrowed between the angles; plants rarely more than 15–100(–120) cm tall | 12 |
| 7a | Sepals 2.5–8 mm; stem usually single, branched or unbranched from base upwards; coastal plain from Florida to North Carolina | Oenothera simulans |
| 7b | Sepals (7–)9–20 mm; stems usually several, branched from base upwards | 8 |
| 8a | Flowers opening near sunrise; plants exclusively strigillose throughout; southwestern Arkansas, and perhaps adjacent Texas and Oklahoma | Oenothera demareei |
| 8b | Flowers opening near sunset; plants with some combination of villous, glandular puberulent, short-hirtellous, strigillose, or subglabrous; rarely exclusively strigillose | 9 |
| 9a | Anthers with pollen 35–65% fertile (sterile pollen smaller); plants villous and glandular puberulent, never strigillose; north-central to north-eastern U.S. | Oenothera gaura |
| 9b | Anthers with pollen 90–100% fertile; plants strigillose, villous, short-hirtellous, or subglabrous | 10 |
| 10a | Plants annual; fruit 4.5–7 mm; central U.S. | Oenothera filiformis |
| 10b | Plants biennial; fruit 6–11 mm; Colorado, Nebraska, New Mexico, and Wyoming | 11 |
| 11a | Plants strigillose proximally, becoming glandular puberulent and strigillose distally; Colorado, Nebraska, and Wyoming | Oenothera coloradensis |
| 11b | Plants villous and strigillose proximally, becoming also glandular puberulent distally and only sparsely villous; Colorado and New Mexico | Oenothera dodgeniana |
| 12a | Sepals 11–20 mm; floral tube 7–20 mm | 13 |
| 12b | Sepals 6–15 mm; floral tube 6–12 mm | 14 |
| 13a | Plants glabrous distally, except sometimes bracts sparsely villous; fruit sessile | Oenothera suffulta |
| 13b | Plants glandular puberulent distally; fruit on a stipe 0.2–2 mm | Oenothera nealleyi |
| 14a | Sepals 6–12 mm long, glandular puberulent, subglabrous or strigillose; Mexico to Arizona, and New Mexico | Oenothera podocarpa |
| 14b | Sepals 10–15 mm, glabrous or strigillose; Texas, Oklahoma, Louisiana, and Alabama | Oenothera patriciae |
Gaura nealleyi J. M. Coulter, Contr. U.S. Natl. Herb. 1: 38. 1890. Gaura suffulta subsp. nealleyi (J. M. Coulter) P. H. Raven & Gregory, Mem. Torrey Bot. Club 23: 81. 1973 [“1972”]. Oenothera suffulta (Engelmann ex A. Gray) W. L. Wagner & Hoch subsp. nealleyi (J. M. Coulter) W. L. Wagner & Hoch, Syst. Bot. Monogr. 83: 214. 2007.
United States. Texas: Presidio County, Chenate [Chinati] region, 1889, G. C. Nealley 545 [the species entry number (150) from Coulter’s publication also on sheet below 545] (Holotype: US-00015158!; isotype: F!).
Gaura suffulta Engelmann ex A. Gray var. terrellensis Munz, Bull. Torrey Bot. Club 65: 121. 1928.
Type: United States. Texas: Terrell County, Sanderson, 1 May 1934, V. L. Cory 8469 (Holotype: POM-200873; Isotype: TAES).
Annual from a stout taproot, usually branched from the base, 20–70 (-100) cm tall, villous proximally, the leaves subglabrous or sparsely villous along the veins and margins, becoming glandular puberulent in the distal portion of the plant, especially on the outside of the floral tube and the sepals. Leaves: rosette leaves lyrate, 3.5–9 × 0.5–1.5 cm, gradually narrowed to the petiole, cauline leaves 1.5–7 × 0.1–0.6 cm, narrowly lanceolate to linear, margin sinuate-dentate, undulate, subsessile. Flowers 4-merous, opening at sunset; floral tube 10–20 mm; sepals 11–21 mm; petals 10–15 mm; staminal filaments 8–13 mm, anthers 2–6 mm, pollen 90–100% fertile; style 22–36 mm. Capsule indehiscent, 4.5–8 × 2–5 mm, nut-like, hard, woody, not reflexed, the body ellipsoid or ovoid, broadly winged on the angles and deeply furrowed between the angles, lower angles or projections of the wings at or above the middle prominent; stipe 0.2–2.2 mm long. Seeds 3–4 (-5), 2–3 (-4) mm, ovoid, usually flattened on one or several sides by crowding in the fruit, yellowish to light brown. Gametic chromosome number: n = 7. Self-incompatible.
Flowering from April to October. Trans-Pecos Texas and northern Coahuila, Mexico, north to Bernalillo and Torrance counties, New Mexico, in washes and other sandy places, grasslands, and extending to pinyon-juniper woodlands; 1220–2140 m.
Gaura suffulta Engelmann ex A. Gray, Bost. J. Nat. Hist. 6: 190. 1850.
United States. Texas: Comal County, New Braunfels, May 1847, F. Lindheimer 611 (Lectotype, designated by Raven & Gregory, 1972 [1973]: 80, GH- 00054125!; Isolectotypes: BM, F!, GH [3]!, K [2]!, LE, M!, MO [3]!, NY!, PH, TEX!, , US[2]!, YU!).
Annual from a stout taproot, moderately branched from the base, 25–120 cm tall, villous proximally, the leaves subglabrous or sparsely villous along the veins and around the margins, becoming glabrous distally or rarely sparsely villous on the bracts. Leaves: rosette leaves 7–11 × 0.1–2.3 cm, lyrate, gradually narrowed to the petiole; cauline leaves 1–9.5 × 0.1–2.3, narrowly lanceolate to linear, margin sinuate-dentate, undulate, subsessile. Flowers 4-merous, opening at sunset; floral tube 6.5–14 mm; sepals 11–21 mm; petals 10–15 mm; staminal filaments 6–9 mm, anthers 2–6 mm, pollen 90–100% fertile; style 16–32 mm. Capsule indehiscent, 4.5–8 × 2–5 mm, nut-like, hard, woody, not reflexed, the body ellipsoid or ovoid, broadly winged on the angles and deeply furrowed between the angles, without prominent lower corners or projections of the wings at or above the middle; stipe 0–1 mm long. Seeds (1-)2–4, 2–2.5 mm, ovoid, usually flattened on one or several sides by crowding in the fruit, yellowish to light brown. Gametic chromosome number: n = 7. Self-incompatible.
Flowering from April to June. Common in western Texas, but rare elsewhere throughout the state and absent in the Trans-Pecos; southern Oklahoma, east to Tulsa, Okfuskee, and Coal counties, and in Woodward County, in open, sandy places; 10–1010 m.
Gaura neomexicana Wooton, Bull. Torrey Bot. Club 25: 307. 1898, non Oenothera neomexicana (Small) Munz (1931). Oenothera coloradensis (Rydberg) W. L. Wagner & Hoch subsp. neomexicana (Wooton) W. L. Wagner & Hoch, Syst. Bot. Monogr. 83: 211. 2007.
United States. New Mexico: Lincoln County, White Mts., 6500 ft, 25 Jul 1897, E. O. Wooton 204 (Holotype: US-330429!; Isotypes: AC!, E!, GH!, K!, LE, MIN, MO! ND, NY [2]!, P, US!).
Biennial from a stout fleshy taproot, with a single or a few branches from the base, 50–120 cm tall, villous and strigillose proximally, leaves subglabrous or strigillose, becoming also glandular puberulent distally, and sometimes also sparsely villous. Leaves: rosette leaves 6–20 × 1–3 cm; cauline leaves 5–10 × 1–2.5 cm, lanceolate to narrowly elliptic, subentire to repand-denticulate. Flowers 4-merous, opening at sunset; floral tube 10–11 mm; sepals 11–15 mm; petals 11–13.5 mm; staminal filaments 6.5–9 mm, anthers 2.5–4 mm long, pollen 90–100% fertile; style 22–28 mm. Capsule indehiscent, 9–11 × 3–5 mm, nut-like, hard, woody, not reflexed, the body ellipsoid or ovoid, sharply 4-angled, with fairly deep furrows alternating with the angles for 2–3 mm from the apex, ribbed from base of furrow to base of the fruit. Seeds 2–4, 2–3 mm, yellowish to light brown. Gametic chromosome number: n = 7. Self-compatible.
Flowering from June to September.In the western foothills of the San Juan Mountains in Archuleta County, Colorado, and Rio Arriba County, New Mexico; Sierra Blanca and Sacramento Mountains in Lincoln and Otero counties, south-central New Mexico. Collected once at Durango, La Plata County, Colorado (
The new name for this species is to honor David and Judy Dodgen of Cloudcroft, New Mexico, landowners who graciously allowed one of us (Krakos) to conduct research on their land, which harbors populations of this rare species. Oenothera dodgeniana and Oenothera coloradensis were considered by
Gaura coloradensis Rydberg, Bull. Torrey Bot. Club 31: 572. 1904. Gaura neomexicana var. coloradensis (Rydberg) Munz, Bull. Torrey Bot. Club 65: 114. 1938. Gaura neomexicana subsp. coloradensis (Rydberg) P. H. Raven & Gregory, Mem. Torrey Bot. Club 23: 63. 1973 [“1972”].
United States. Colorado: Larimer County, Ft. Collins, 5000 ft, 8 Jul 1895, J. M. Cowen s.n. (Holotype: NY-BC00232160!; Isotype: GH!).
Biennial from a stout, fleshy taproot, with several branches from the base, 50–80(-100) cm tall, strigillose proximally, becoming glandular puberulent and strigillose distally. Leaves: rosette leaves 4–18 × 1.5–4 cm; cauline leaves 5–13 × 1–4 cm, very narrowly elliptic, subglabrous or strigillose, margin subentire to repand-denticulate. Flowers 4-merous, opening at sunset; floral tube 8–12 mm; sepals 9.5–13 mm; petals 7–12 mm; staminal filaments 6.5–9 mm, anthers 2.5–4 mm, pollen 90–100% fertile; style 19–25 mm. Capsule indehiscent, 6–8.5 × 2–3 mm, nut-like, hard, woody, not reflexed, the body ellipsoid or ovoid, sharply 4-angled, with fairly deep furrows alternating with the angles for 2–3 mm from the apex, ribbed from base of furrow to base of the fruit. Seeds 1–4, 2–3 mm, yellowish to light brown. Gametic chromosome number: n = 7. Probably self-compatible.
Flowering in July and August.In early successional vegetation of the North and South Platte River watersheds on the high plains, sloping floodplains, and drainage base in heavy soils, from southern Laramie and Platte counties in Wyoming, northern Weld County, Colorado, formerly near Fort Collins, Larimer County, Colorado, and in western Kimbal County, Nebraska; 1530–1950 m.
The Colorado butterfly plant is currently known from fewer than two dozen populations and has been federally listed as a Threatened species in the U.S. (
Gaura podocarpa Wooton & Standley, Contr. U.S. Natl. Herb. 16: 154. 1913.
United States. New Mexico: Grant County, Bear Mt., near Silver City, 1500 m, 17 June 1903, O. B. Metcalfe166 (Holotype: US-495277!; Isotypes: DS, E!, G, GH!, LE, MIN!, MO!, NMC! POM, US!).
Gaura gracilis Wooton & Standley, Contr. U.S. Natl. Herb. 16: 153. 1913. Gaura hexandra subsp. gracilis (Wooton & Standley) P. H. Raven & Gregory, Mem. Torrey Bot. Club 23: 87. 1973 [“1972”].
United States. New Mexico: Grant County, Ft. Bayard forest nursery, 29 Aug 1905, J. C. Blumer 44 (Holotype: US-499693!; isotypes: GH!). Epithet not available in Oenothera as there are two earlier uses: Oenothera gracilis (Phil.) H. Léveillé, 1905 (syn. for Gayophytum micranthum Hooker & Arnott) and Oenothera gracilis Schrader ex Fischer & Meyer, 1835 (syn. For Oenothera perennis L.).
United States. New Mexico: Lincoln County, Wingfields Ranch on Ruidosa Creek, White Mts, 8 July 1895, E. O. Wooton s.n. (Holotype: US-561073!).
United States. New Mexico: Socorro County, Socorro, May 1881, G.R. Vasey s.n. (Holotype: US-45764!).
United States. New Mexico: Catron County, Reserve, 9 July 1906, E. O. Wootons.n. (Holotype: US 561072!; Isotype: US!).
Annual herb from a stout taproot, usually well-branched at the base and above, 15–100 cm tall, villous proximally, the leaves subglabrous to densely short-villous, becoming subglabrous, strigillose and/or glandular puberulent distally. Leaves: rosette leaves lyrate, 3–15 × 0.5–1 cm; cauline leaves 1–9 × 0.1–0.8 cm, linear to very narrowly elliptic or narrowly lanceolate, sinuate-dentate to subentire, subsessile. Flowers 4-merous, opening at sunset; floral tube 6–10 mm; sepals 6–12 mm; petals 5.5–9.5 mm; filaments 4–6 mm, anthers 2–3 mm, pollen 90–100% fertile; style 11–18.5 mm. Capsule indehiscent, 6–8 × 2–3 mm, nut-like, hard, woody, not reflexed, broadly winged on the angles and deeply furrowed between the angles, the body ellipsoid or narrowly obovoid, narrowed at the base but not stipitate. Seeds 4, 2–3 mm, ovoid, usually flattened on one or several sides by crowding in the fruit, yellowish to reddish brown. Gametic chromosome number: n = 7. Self-compatible.
Flowering from (May) June to October. In Arizona from eastern Mohave County south through the mountains of central Arizona to eastern Pima County and the southwestern quarter of New Mexico, and in Mexico southward in the Sierra Madre Occidental to eastern Sonora and throughout the western halves of Chihuahua and Durango, often in disturbed sites in or on sandy washes, slopes, grasslands, meadows, pinyon-juniper or ponderosa pine woodlands, and sometimes on volcanic cinders; 760–2750 m.
Oenothera podocarpa is the first species to branch off in the subsect. Gaura clade (Fig. 1), whereas Oenothera hexandra is nested well within the subsect. Gaura clade. The epithet “podocarpa” was selected among the three equally available names at the species rank for this species. Previously, Gaura gracilis, one of four species published simultaneously by Wooton and Standley, was selected by
Gaura hexandra Ortega, Hort. matr. dec. 14. 1797.
Based on living plants cultivated at the Royal Botanical Garden in Madrid from seeds sent by Sessé from Mexico [erroneously said to be from Cuba] (Holotype: not located).–Mexico. México. Comunidad Temascaltepec, 19 May 1936, G. B. Hinton 7688 (Neotype, designated, by
Annual herb from a stout taproot, usually well-branched at the base and above, 15–100 cm tall, villous proximally, the leaves subglabrous to densely short-villous, and becoming subglabrous, strigillose, and/or glandular-puberulent distally. Leaves in a basal rosette and cauline; rosette leaves lyrate, gradually narrowed to the petiole, usually quickly deciduous; cauline leaves 1–9 × 0.1–0.8 cm, linear to very narrowly elliptic or narrowly lanceolate, margin sinuate-dentate to subentire, subsessile. Inflorescence strict to somewhat branched, 7–53 cm long, bracts 2–5 cm long, narrowly lanceolate to ovate. Flowers 3-merous, opening at sunset; floral tube 4.5–7.5 mm; sepals 3–10 mm; petals 4.5–7 mm; staminal filaments 3–6 mm, anthers 1–2 mm, pollen 90–100% fertile; style 9–14.5 mm. Capsule indehiscent, 4.5–8 × 2–4.5 mm, nut-like, hard, woody, not reflexed, the body ellipsoid or narrowly obovoid, broadly winged on the angles and deeply furrowed between the angles, narrowed at the base but not stipitate. Seeds 3, 1.75–3 mm, ovoid, usually flattened on one or several sides by crowding in the fruit, yellowish to reddish brown. Gametic chromosome number: n = 7. Self-compatible and highly autogamous.
Flowering from March to November. From Durango, Mexico south in the Sierra Madre Occidental to the Trans Mexican Volcanic Belt, where abundant, and in Chiapas, Mexico as well as Guatemala in grasslands, meadows or oak woodlands, or disturbed areas, in sandy soils; 1800–2430 m.
A nomenclatural problem in Oenothera sect. Calylophus is corrected here by adopting the name Oenothera capillifolia Scheele for the species known previously, and nomenclaturally correct, as Calylophus berlandieri Spach when the genus Calylophus is recognized as distinct from Oenothera; however, when this species is considered to be a member of Oenothera as it was recently by
Meriolix capillifolia (Scheele) Small, Fl. S.E. U.S. 846, 1335. 1903.
United States. Texas: Comal County, NewBraunfels, April (1846?), Ferdinand Roemers.n. (not located). —United States. Texas: Comal County, NewBraunfels, May 1850, F. Lindheimer 809 (Neotype: here designated, US-502186!; Isoneotypes: ARIZ, DS, F, GH, MO!, NMC, NY, OKL, PH, TEX, UC).
Oenothera serrulata var. pinifolia Engelmann in A. Gray, Bost. J. Nat. Hist. 6: 189. 1850. Meriolix serrulata var. pinifolia (Engelmann) Small, Bull. Torrey Bot. Club 23: 187. 1896. Oenothera serrulata subsp. pinifolia (Engelmann) Munz, N. Amer. Fl., ser. 2, 5: 141. 1965. Calylophus berlandieri subsp. pinifolius (Engelmann) Towner, Ann. Missouri Bot. Gard. 64: 107. 1977.
United States. Texas: Comal County, New Braunfels, Apr-May 1846, F. Lindheimer 394 (Holotype: MO-122323!; Isotypes: DS, GH [2]!, K [3]! MO!, NY!, PH, RSA, US!, YU!).
Calylophus berlandieri Spach, Ann. Sci. Nat. Bot., sér. 2, 4: 272. Nov. 1835. Oenothera berlandieri (Spach) Steud., Nom. Bot., ed. 2. 2: 206. 1841, non D. Dietr. Dec. 1840. Meriolix berlandieri (Spach) Walp., Repert. Bot. Syst. 2: 79. 1843. Calylophus drummondianus Spach subsp. berlandieri (Spach) Towner & Raven, Madroño 20: 243. 1970.
United States. Texas: Bahia del Espiritu Santo [probably in present Calhoun County, March or May 1829], Jean Louis Berlandier 539=1919 (Holotype: P; Isotypes: GH!, PH).
We thank Tim Lowrey and Phil Tonne for images of UNM herbarium collections. We appreciate the useful review comments by George Yatskievych, and edits to the manuscript by Nancy Khan.