Wisteria
Wisteria × formosa
wisteria
twining counterclockwise or clockwise, high-climbing or scandent, pubescent or glabrescent;
peduncles and pedicels usually eglandular, pedicels sometimes with clavate glands.
alternate, odd-pinnate;
stipules present, linear-lanceolate;
petiolate;
leaflets (7 or)9–17(or 19), stipels linear-lanceolate, blade margins entire, surfaces glabrous or villous.
30–100-flowered, terminal, pendent racemes;
bracts present, caducous, lanceolate, pubescent, sometimes with clavate glands.
ebracteolate, sometimes with clavate glands, pubescent.
papilionaceous;
calyx campanulate, bilabiate, pubescent, lobes 5, abaxial lip 3-lobed, middle lobe long-acuminate, adaxial lip 2-lobed;
corolla azure, purple, rose, or white, petals subequal, banner reflexed at a 2-auricled callosity near middle or base, wings oblong-falcate, 1-clawed with auricle at one or both sides of base, keel incurved, petals connate at apices;
stamens 10, diadelphous;
anthers basifixed;
ovary stipitate, with disc surrounding stipe.
legumes, stipitate, erect, flattened bilaterally or cylindric, torulose, oblong-elliptic, oblanceolate, or linear-oblong, 2-valved, explosively or tardily dehiscent, constricted between seeds, glabrous or pubescent.
1–5 (rarely more in W. frutescens), black, sometimes mottled brown, reniform or lenticular.
, perennial, woody, unarmed;
with long-creeping rhizomes.
= 8.
Wisteria
Wisteria × formosa
Species 8 (4, including 1 hybrid, in the flora).
Wisteria japonica, W. sinensis, and W. × formosa are commonly cultivated and have become naturalized in the flora area. Native W. frutescens is becoming more popular in cultivation as the invasive nature of the Asian taxa is better understood by consumers. All parts of Wisteria plants contain toxins that can cause severe nausea, vomiting, and abdominal cramping (L. S. Nelson et al. 2007).
Four additional generic names pertain here: Diplonyx Rafinesque and Phaseoloides Duhamel are both rejected names against which Wisteria is conserved; Kraunhia Rafinesque is an invalid name; and Thyrsanthus Elliott, not Schrank 1814, is illegitimate.
Recognition of Rehsonia as separate from Wisteria (L. R. Stritch 1984) was based on differences in position of the banner petal callosity and the place of reflexing of the banner petal, legume characters, and seed traits. In Rehsonia, the banner is reflexed at the base at the auricled callosity, the ovary is pubescent, the legume is thick and coriaceous, tardily dehiscent, flattened, and pubescent, with valves that split easily into an endocarp and exocarp, and the seeds are flat and lenticular. In Wisteria in the narrow sense, the banner is reflexed at the middle of its length at the auricled callosity, the ovary is glabrous, the legume is thin, explosively dehiscent, cylindric, and glabrous, with valves that do not split into an endocarp and exocarp, and the seeds are plump and reniform. Recognition of these as separate genera has not been borne out in subsequent molecular studies (Hu J. M. et al. 2000; Li J. H. et al. 2014), and Wisteria is consequently being recognized here in the broader, traditional sense.
Anthesis within a raceme may be gradual, with anthers of flowers at the inflorescence base abscising while those at the apex are still in bud, or more or less simultaneous, with the anthers abscising at about the same time.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Banners reflexed at middle; ovaries glabrous; legumes plump, glabrous, explosively dehiscent; seeds plump, reniform. | W. frutescens |
1. Banners reflexed at base; ovaries pubescent; legumes flattened, pubescent, tardily dehiscent; seeds flat, lenticular. | → 2 |
2. Flowers unscented, appearing before leaves, anthesis within a raceme nearly simultaneous; banners 2.1–2.4 × 2.1–2.3 cm; stems twining counterclockwise. | W. sinensis |
2. Flowers scented, appearing with or after leaves, anthesis within a raceme gradual, those at base abscising while those at apex still in bud; banners 1.6–1.8 × 1.6–1.8 cm; stems usually twining clockwise, rarely counterclockwise. | → 3 |
3. Banners: auricles of callosity 1.1–1.2 mm, apex acuminate; stems twining clockwise. | W. floribunda |
3. Banners: auricles of callosity 0.7–0.8 mm, apex rounded; stems usually twining counterclockwise, rarely clockwise. | Wisteria × formosa |
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