Chylismia sect. Chylismia
Onagraceae tribe Onagreae
alternate or basal;
stipules absent.
usually opening at sunrise, rarely at sunset;
floral tube 0.4–9 mm;
petals usually bright yellow, rarely white or cream, usually with red dots basally, or lavender to purple with white or yellow basally, sometimes with darker flecks near base, fading yellow, orange, reddish, or lavender;
pollen shed singly.
usually actinomorphic, rarely slightly zygomorphic (in Oenothera), (3 or)4-merous;
stamens 2 times as many, or rarely as many, as sepals;
pollen usually shed in monads, rarely tetrads (Chylismia sect. Lignothera).
a dry capsule, usually dehiscent, sometimes indehiscent.
few to numerous, without hairs or wings, [very rarely with asymmetrical dry wing (Xylonagra)], or with dry (Oenothera), erose or smooth wing, or with thick, papillate wings (Chylismiella).
Chylismia sect. Chylismia
Onagraceae tribe Onagreae
Species 14 (14 in the flora).
Section Chylismia consists of 10 diploid (2n = 14) species, and two that are partly polyploid (2n = 14, 28) [C. scapoidea subsp. scapoidea and C. walkeri subsp. walkeri (only one tetraploid population)]; no chromosome counts are available for the remaining two species, C. atwoodii and C. confertiflora (P. H. Raven 1962, 1969). Species of sect. Chylismia usually occur on sandy desert slopes, flats, and washes, often in sagebrush shrubland in the northern part of its range, or on rock slides or cliffs, mainly in the Mojave and northwestern Sonoran deserts, the Great Basin, and the lower elevations of the surrounding Sierra Nevada and Rocky Mountains. The limits of this range stretch from southeastern Oregon, central and southern Idaho, and central Wyoming, south through Nevada and Utah to eastern and southeastern California, northern Baja California and northwestern Sonora, Mexico, Arizona, northwestern New Mexico, and western Colorado. Several species are rare; C. confertiflora and C. specicola are known only from the Grand Canyon in northwestern Arizona, C. megalantha only from the vicinity of the type locality in Nye County, Nevada, and C. atwoodii also only from a narrow area around its type locality in Kane County, Utah. Others are widespread, especially the very diverse C. claviformis (11 subspp.), C. scapoidea (4 subspp.), C. walkeri (2 subspp.), and C. brevipes (3 subspp.). Chylismia scapoidea is the only species in the genus to occur east of the continental divide, both in Colorado on the upper Arkansas River in Fremont and Pueblo counties, and much more widely in Wyoming. Chylismia does not occur west of the Cascade-Sierra Nevada axis. Because R. A. Levin et al. (2004) included only C. claviformis in their analysis, they did not test the monophyly of sect. Chylismia; however, this section is both geographically distinct and morphologically set apart by the characteristic pinnate leaves (modified in some species, which have retained the entire apical lobe but do not have the smaller lateral lobes). Most species have bright yellow petals with red dots proximally and ultraviolet reflectance distally; some subspecies of C. claviformis have white petals; three species (C. atwoodii, C. heterochroma, and C. megalantha) have lavender or purple petals, often with lavender or purple flecks toward base, and white or yellow at the base and no reflectance, clearly a derived condition within the section (Raven 1962, 1969).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genera 13, species 265 (12 genera, 199 species in the flora).
Onagreae account for more than half the total genera in Onagraceae and diversified from a center in southwestern North America (L. Katinas et al. 2004). Delimitation of the tribe by W. L. Wagner et al. (2007) differs from previous ones by the exclusion of Gongylocarpus, now in its own tribe, by the segregation of eight genera (Camissoniopsis, Chylismia, Chylismiella, Eremothera, Eulobus, Neoholmgrenia, Taraxia, and Tetrapteron) from Camissonia, and by the inclusion of three previously separate genera (Calylophus, Gaura, and Stenosiphon) in Oenothera. Within the branch of the family that lacks stipules (Gongylocarpeae, Epilobieae, and Onagreae), the last two tribes form a clade that has very strong molecular support (R. A. Levin et al. 2003, 2004), but no obvious morphological synapomorphy. The clade may be defined by a cytogenetic change from the base chromosome number of x = 11 found in Circaeeae, Gongylocarpeae, and Lopezieae, to x = 18 in Epilobieae, and x = 7 in Onagreae; however, these changes could also have occurred independently. Other than the new chromosome number x = 7, the only apparent morphological synapomorphy for Onagreae alone is pollen with prominent apertural protrusions (J. Praglowski et al. 1987, 1989), a character state also found in Circaeeae (Praglowski et al. 1994). The monophyly of Onagreae has moderate (Levin et al. 2004) to strong support (V. S. Ford and L. D. Gottlieb 2007).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Stamens usually 4, rarely 8, then antipetalous anthers abortive, smaller. | C. exilis |
1. Stamens 8, anthers all fertile. | → 2 |
2. Petals lavender or purple, often with purple or lavender flecks near base. | → 3 |
3. Stigma surrounded by anthers at anthesis, plants autogamous; petals 2–6 mm. | C. heterochroma |
3. Stigma exserted beyond anthers at anthesis, plants outcrossing; petals 7–14 mm. | → 4 |
4. Capsules 8–14 mm, erect or ascending; floral tubes 4–9 mm. | C. megalantha |
4. Capsules 11–25 mm, spreading to reflexed; floral tubes 0.6–1 mm. | C. atwoodii |
2. Petals yellow or white, often with red dots at base. | → 5 |
5. Capsules distinctly clavate. | → 6 |
6. Stigma surrounded by anthers at anthesis; petals 1.5–5.5(–8) mm. | C. scapoidea |
6. Stigma exserted beyond anthers at anthesis; petals 2–10 mm. | → 7 |
7. Mature capsules sharply reflexed; petals bright yellow. | C. munzii |
7. Mature capsules ascending, spreading, erect, or slightly reflexed; petals yellow or white. | → 8 |
8. Raceme branches intricate and filiform; leaves in poorly defined basal rosette; capsules 4–10 mm. | C. parryi |
8. Raceme branches not filiform; leaves primarily in well-defined basal rosette; capsules 8–40 mm. | → 9 |
9. Stamens subequal; leaves usually pinnately lobed, with well-developed lateral lobes, sometimes these reduced or absent, margins dentate, sinuate-dentate, or serrate. | C. claviformis |
9. Stamens unequal, differentiated into 2 sets; leaves usually unlobed, rarely pinnately lobed with reduced lateral lobes, margins entire or sparsely denticulate. | C. eastwoodiae |
5. Capsules oblong-cylindrical. | → 10 |
10. Stigma surrounded by anthers at anthesis; petals 1–6 mm; styles 1.5–6(–7) mm; racemes erect in bud, mature buds individually reflexed. | → 11 |
11. Plants perennial, base sometimes woody; leaf blades glabrous or sparsely villous; anthers glabrous. | C. specicola |
11. Plants annual or short-lived perennial, base not woody; leaf blades moderately to densely villous; anthers glabrous or sparsely ciliate. | C. walkeri |
10. Stigma exserted beyond anthers at anthesis; petals 3–18 mm; styles 7–18 mm; racemes erect or nodding in bud, mature buds individually reflexed or not. | → 12 |
12. Racemes erect to nodding, elongating in bud, mature buds individually reflexed; plants virgate; floral tubes 1–3 mm. | C. multijuga |
12. Racemes nodding, mostly elongating after flowers open; plants not virgate; floral tubes 3–8 mm. | → 13 |
13. Buds without free tips or with subapical free tips 1–2 mm, or with minute apical free tips less than 1 mm, and then bud pubescent but not glandular puberulent; plants branched or unbranched distally; stamens subequal. | C. brevipes |
13. Buds with subapical free tips 1–2 mm, glandular puberulent; plants well branched; stamens differentiated into 2 sets. | C. confertiflora |
