Oenothera sect. Lavauxia

(Spach) Walpers

Repert. Bot. Syst. 2: 83. 1843.

Basionym: Lavauxia Spach Hist. Nat. Vég. 4: 366. 1835
Synonyms: Oenothera [unranked] Lavauxia (Spach) Endlicher Oenothera subg. Lavauxia (Spach) Reichenbach
Treatment appears in FNA Volume 10.

Herbs usually perennial, sometimes annual or biennial, usually acaulescent or short-caulescent; from a taproot, sometimes lateral roots producing adventitious shoots. Stems (when present) ascending [or decumbent]. Leaves in a basal rosette, sometimes also cauline, (4–) 8–36 cm; blade margins coarsely pinnatifid or lobed to dentate or subentire. Inflorescences solitary flowers in axils of leaves. Flowers opening near sunset, with a slightly sweet fragrance and a spermaceous background odor, or nearly unscented; buds erect, obtusely quadrangular, with unequal or subequal free tips; floral-tube (20–) 40–200 (–265) mm; sepals splitting along one suture, remaining coherent and reflexed as a unit at anthesis or separating in pairs; petals yellow [white], fading orange to lavender, drying purple to lavender or purplish brown, obovate with acute apex or obcordate; stigma deeply divided into 4 linear lobes. Capsules leathery or woody in age, usually narrowly ovoid or ellipsoid to rhombic-obovoid, sometimes ovoid or lanceoloid, winged, wings oblong to triangular in distal [1/2–] 2/3 of capsule, constricted to a short beak, dehiscent 1/4–1/2 their length; sessile. Seeds numerous, usually in 2 rows per locule, rarely 3 adjacent and distinct rows (O. triloba), asymmetrically cuneiform, narrowly winged distally, also along one adaxial margin, surface minutely beaded. 2n = 14.

Distribution

w, c North America, n, c Mexico, s South America

Discussion

Species 5 (3 in the flora).

Section Lavauxia consists of five diploid (n = 7) species, divided into two subsections, which are locally common in seasonally wet depressions, flats, meadows, stream banks, or disturbed sites from southern Canada through the western and east-central United States to central Mexico, disjunct in Baja California, and two species in southern South America, at 0–3200 m elevation. The monophyly of sect. Lavauxia is strongly supported, but its relationships to the rest of the genus are obscure. No member of the South American subsect. Australis has been included in molecular analyses, but it shares unique morphological features with the North American subsect. Lavauxia; the monophyly of this section is not in doubt, based on the shared dandelionlike acaulescent habit and unique capsule morphology. Species are self-compatible or, rarely, apparently self-incompatible (some plants of O. acutissima); flowers vespertine, fragrance pungent, often slightly sweet with a spermaceous background scent in O. acutissima and outcrossing populations of O. flava, or without noticeable scent in autogamous populations of O. flava and in O. triloba. Species are outcrossing and pollinated by hawkmoths (O. acutissima and large-flowered populations of O. flava) or autogamous, occasionally cleistogamous in O. flava (W. L. Wagner et al 2007; R. A. Raguso et al. 2007; H. E. Summers et al. 2015).

Selected References

None.

"/4" is not declared as a valid unit of measurement for this property.

... more about "Oenothera sect. Lavauxia"
Warren L. Wagner +
(Spach) Walpers +
pale green +  and yellow usually fading orange purple pale-yellow reddish or whitish +
pedicel-like +
Lavauxia +
indehiscent +  and loculicidal +
lobed +  and dentate or subentire +
quadrangular +
curved +  and straight +
indehiscent +  and dehiscent +
lanceoloid +, ovoid +, ellipsoid +  and rhombic-obovoid +
woody +  and leathery +
w +, c North America +, n +, c Mexico +  and s South America +
whitish +  and green +
exfoliating +
basifixed +  and versatile +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
20 cm200 mm <br />0.2 m <br /> (26.5 cm265 mm <br />0.265 m <br />) +
hispid +, lanate +  and glabrous +
4 cm40 mm <br />0.04 m <br /> (20 cm200 mm <br />0.2 m <br />) +
zygomorphic +  and actinomorphic +
unscented +
curved +  and straight +
indehiscent +  and dehiscent +
4-angled +, terete +, tapering +, cylindrical +, ellipsoid +, clavate +, ovoid ellipsoid +  and cylindrical rhombic-obovoid or globose +
short-caulescent +  and acaulescent +
biennial +, annual +  and perennial +
suffrutescent +
nodding +  and erect +
4 cm40 mm <br />0.04 m <br /> (8 cm80 mm <br />0.08 m <br />) +
deciduous +
8 cm80 mm <br />0.08 m <br /> (36 cm360 mm <br />0.36 m <br />) +
pedicellate +  and sessile +
1 +  and 8 +
fading orange +  and lavender drying purple +
obcordate +  and obovate +
Repert. Bot. Syst. +
basal +  and cauline +
distinct +
clavate +  and globose +
sculptured +  and smooth +
cuneiform +
reduced +
purple +, pink +, red +  and green +
deciduous +
coherent +
parietal +, axile +  and placentation +
unequal +
adventitious +
aquatic +, amphibious +  and terrestrial +
in 2 unequal series +  and subequal +
2 times as many or as many as sepals +
petiolate +  and sessile +
intrapetiolar +
pubescent +  and glabrous +
aquatic +, amphibious +  and terrestrial +
smooth +, reticulate +  and furrowed +
rugose +, papillose +  and non-papillate +
Oenothera +  and Oenothera subg. Lavauxia +
Oenothera sect. Lavauxia +
Oenothera +
section +
3(-5)-aperturate +
subequal +  and unequal +
woody +  and hard +
papillate +
oblong +  and triangular +
constricted +