Galactia |
Galactia wrightii |
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milkpea |
Wright's milkpea |
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Habit | Herbs, perennial, [subshrubs, rarely shrubs], unarmed; with rhizomes, from woody taproot elongate or fusiform. | Herbs from woody taproot. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Stems | procumbent or twining and climbing, glabrous or with spreading or appressed hairs. |
procumbent proximally, weakly twining distally, strongly lignescent, densely to sparsely strigose, hairs retrorsely appressed to slightly spreading. |
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Leaves | alternate, unifoliolate or odd-pinnate; stipules present, deciduous or persistent; petiolate; leaflets 1 or 3(–9), stipels persistent, blades 6–85 mm, margins entire, surfaces pubescent or glabrous. |
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Leaflets | 3, blades oblong-elliptic to elliptic-ovate, 15–48 × 5–18 mm, herbaceous, veins not raised, apex rounded to obtuse or shallowly retuse, surfaces moderately to densely strigose-sericeous and glaucous abaxially, sparsely to densely short-strigose-sericeous with closely appressed hairs to pubescent with soft, spreading-erect hairs, sometimes strigose to glabrous, adaxially. |
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Inflorescences | 1–25(–38)-flowered, axillary [terminal], usually pseudoracemes, pedunculate or without axis and flowers in axillary fascicles, sometimes flowers solitary; rachis with slightly swollen nodes; bracts present, setaceous; bracteoles minute, caducous, rarely tardily so. |
flowers (2–)5–18(–30) in pseudoracemes, usually in fascicles, axis rarely 10 mm and 2- or 3-flowered; axis (10–)35–200(–250) mm. |
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Flowers | papilionaceous, solitary, paired, or fascicles of 2 or 3 at nodes; calyx campanulate, lobes 5 appearing as 4, adaxial 2 completely connate; corolla usually purplish to bluish, pink, rose, violet, or lavender, rarely white [red], 6–15(–17) mm; petals subequal, banner orbiculate to ovate or obovate-orbiculate, margins slightly inflexed or appendaged, apex rounded, wings narrow or obovate, adherent to keel, keel obtuse and almost straight, subequal to or longer than wings, carinate or moderately incurved; stamens 10, diadelphous [pseudomonadelphous], vexillary stamen free or proximally connate from middle; anthers dorsifixed; ovary subsessile; style filiform, glabrous; stigma terminal, capitate; nectary at ovary base. |
calyx 5–7 mm, loosely short-strigose to hirsute-pubescent, lobes greenish yellow to tan on inner surface when dry; corolla not persisting after anthesis, pink to purple-rose to lavender, lighter when dry, 11–12 mm. |
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Fruits | legumes, sessile, brown, laterally compressed, straight or weakly to strongly falcate, linear, with false septae between seeds, elastically dehiscent, pubescent. |
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Legumes | straight, 25–50 × 4–5 mm, moderately to densely strigose to strigose-sericeous. |
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Seeds | 1–12, brown or brownish orange, flattened, oblong, 3–7 mm, estrophiolate. |
(3–)5–9. |
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x | = 10. |
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Galactia |
Galactia wrightii |
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Phenology | Flowering May–Aug. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Habitat | Grasslands, desert scrub, oak-juniper and oak woodlands, granite crevices, igneous talus, among boulders, gravelly alluvium. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Elevation | 700–1900 m. (2300–6200 ft.) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Distribution |
United States; Mexico; Central America; South America; West Indies; Asia; Africa; Australia |
AZ; NM; TX; Mexico (Chihuahua, Sonora)
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Discussion | Species ca. 110 (21 in the flora). Most Galactia species are native to the Americas, distributed fairly evenly across the southeastern and south-central United States, Mexico, West Indies, Central America, and South America. Diversity in the flora area is concentrated in Florida and Texas, with relatively fewer species in Mexico and Central America. Three species of Galactia are native to Asia, Africa, and Australia. An overview of the genus in the flora area and a summary of previous studies worldwide were provided in G. L. Nesom (2015). The Texas species G. watsoniana W. C. Holmes & Singhurst is a synonym of Cologania pallida Rose (Nesom). Three sections have been recognized within Galactia (A. Burkart 1971), emphasizing the South American species. Most species of Galactia, including all of those in the flora area, are placed in sect. Odonia (Bertoloni) Burkart in the sense of Burkart. Galactia forms a group in the Diocleinae Bentham together with three or four other genera: Camptosema Hooker & Arnott, Collaea de Candolle, and Lackeya. R. H. Maxwell and D. W. Taylor (2003) included the Caribbean Rhodopis Urban in their Galactia clade. Phylogenetic studies indicate that Galactia is not monophyletic (L. P. de Queiroz et al. 2003; S. M. Sede et al. 2008, 2009; G. B. Ceolin 2011), but relatively few species have been included in analyses. Galactia appears to be paraphyletic without the inclusion of some species of Camptosema and perhaps the entire genus Collaea. In addition, the sections as circumscribed by Burkart do not appear to be monophyletic. R. H. Maxwell (1979) placed the eastern North American Dioclea multiflora in Galactia as G. mohlenbrockii R. H. Maxwell; R. H. Fortunato et al. (1996) segregated D. multiflora as the monospecific Lackeya. This placement is supported by molecular analyses (L. P. de Queiroz et al. 2015). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Galactia wrightii is characterized by twining stems, mostly oblong-elliptic leaflets with glaucous abaxial surfaces, relatively long inflorescences with numerous flowers and relatively large corollas, and strigose-sericeous fruits. The type of var. mollissima is a plant with vestiture more spreading than normal; such variants are scattered through the range in Arizona, as cited by Kearney and Peebles, as well as in Texas. Plants in southwestern New Mexico and southeastern Arizona (especially the Huachuca Mountains but not the Chiricahua Mountains) tend to have reduced vestiture; the leaves are sometimes completely glabrous. Such plants extend southward in Mexico along the Chihuahua-Sonora border region. Intermediates are numerous, especially in Arizona, and no distinct boundary seems evident. In Texas, G. wrightii is known from four counties of the trans-Pecos and Big Bend regions. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 11. | FNA vol. 11. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Synonyms | Heterocarpaea, Odonia | G. tephrodes, G. wrightii var. mollissima | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Name authority | P. Browne: Civ. Nat. Hist. Jamaica, 298, plate 32, fig. 2. (1756) | A. Gray: Smithsonian Contr. Knowl. 3(5): 44. (1852) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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