Rhinotropis |
Rhinotropis rimulicola |
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milkwort |
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Habit | Herbs, perennial, subshrubs, or shrubs, single- or multi-stemmed, with or without thorns, then as modified tips of racemes. | Herbs or subshrubs, multi-stemmed, often loosely mat-forming to 2.5 dm diam., 0.1–0.5 dm. | ||||||||||||||||||||||||||||||||||||||||||||||||
Stems | usually sprawling to erect, sometimes prostrate or decumbent, usually not glaucous, pubescent or glabrous. |
prostrate to laxly erect, glabrous or very sparsely pubescent, hairs incurved. |
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Leaves | alternate; sessile, subsessile, or petiolate; usually not strongly dimorphic; blade surfaces pubescent or glabrous. |
sessile or subsessile; blade elliptic, obovate, ovate, or scalelike, (1.5–)2–5.9(–8) × 0.8–3.5 mm, base cuneate or rounded, apex acute, surfaces sparsely pubescent to subglabrous, hairs incurved. |
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Racemes | terminal, sometimes appearing axillary (from branches proximal to racemes of major branches with vegetative portions highly reduced), reduced to 1–3(–5) flowers, 0.5–1 × 0.7–1.9 cm; peduncle 0–0.2 cm; rachis not thorn-tipped; bracts persistent, ovate, lanceolate, or linear. |
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Inflorescences | terminal or leaf-opposed, sometimes appearing axillary if poorly developed, racemes, sometimes reduced and appearing fasciculate or aggregated into pseudopanicles; peduncle present or absent; bracts deciduous to subpersistent or persistent. |
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Pedicels | present. |
(0.6–)1–3(–3.6) mm, usually glabrous, rarely sparsely pubescent. |
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Flowers | cream, yellowish green,yellow, white, pink, rose, or purple, cleistogamous usually absent, sometimes present (in R. californica and R. lindheimeri), (2.4–)3.5–14.5 mm; sepals deciduous or persistent (when persistent, usually only upper; all persistent in R. rusbyi), sometimes appearing very slightly connate basally, pubescent or glabrous; wings deciduous, 2.5–12.5 mm, glabrous or pubescent; keel usually beaked with unlobed projection, beak sometimes reduced or obscure (rarely on all flowers unless cleistogamous, and then inflorescence usually proximal), keel glabrous or pubescent; stamens usually 7 or 8, rarely 9 (in R. acanthoclada), in chasmogamous flowers, fewer in cleistogamous flowers, not grouped; ovary 2-loculed. |
pink or purple with pale margins, keel sometimes cream, distally greenish yellow, (2.4–)2.9–5.1(–5.4) mm; sepals: lateral ones deciduous, elliptic, ovate, or obovate, (1.2–)1.6–3(–3.2) mm, upper sepal persistent, ovate, (1–)1.2–2.4 mm, glabrous, margins sometimes sparsely ciliate proximally; wings obovate, (2.2–)2.5–4.6(–5.1) × 1.8–2.8 mm, glabrous or sparsely pubescent proximally; keel (1.7–)2.3–3.6 mm, sac incurved-puberulent in distal 1/2, beak obscure, deltate, bluntly rounded, or linear to oblong, (0–)0.1–0.7 × (0–)0.1–0.5 mm, glabrous. |
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Fruits | capsules, dehiscent, margins winged or not, glabrous or pubescent. |
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Capsules | ellipsoid-obovoid, sometimes broadly so, 1.9–3.6 × 1.6–2.9 mm, base cuneate to rounded, margins narrowly and evenly winged or slightly expanded apically, glabrous or sparsely pubescent apically. |
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Seeds | pubescent to subglabrous, arillate. |
(1.7–)1.9–3.2 mm, body, excluding aril and pubescence, 1–1.9 mm, densely pubescent; aril (0.3–)0.4–0.7 mm, lobes often highly reduced, nearly absent to 1/6 length of seed. |
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x | = 9. |
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Rhinotropis |
Rhinotropis rimulicola |
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Distribution | w United States; sc United States; Mexico; Central America (Guatemala) |
sw United States; sc United States |
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Discussion | Species 17 (12 in the flora). Of the 17 species of Rhinotropis ranging from the southwestern United States and/or Mexico, only R. purpusii (Brandegee) J. R. Abbott extends into Guatemala. Of all the genera treated here, this is the only one that has been monographed within the last 100 years (T. L. Wendt 1978). Rhinotropis is probably sister to the Caribbean clade Phlebotaenia Grisebach, and appears to be fairly closely related also to the pantropical (although predominantly neotropical) genus Securidaca Linnaeus. Rhinotropis is largely endemic to arid regions but some species (R. californica) occur in mesic areas. The flower beak is a cylindric, conic, or contorted non-fimbriate hollow projection from the lower (or central) apex of the keel region. It is highly reduced or absent in some species. The other diagnostic features of Rhinotropis are also not monothetic across all species. Many species have the upper sepal persistent in fruit and the other sepals, including the wings (and the corolla), deciduous. Unlike other North American Polygalaceae, species of Rhinotropis often have five petals; the lateral petals are much reduced, linear, and adnate for most of their length to the staminal column; additionally, several species are shrubs and a few have thorn-tipped inflorescence axes. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Varieties 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 10. | FNA vol. 10. | ||||||||||||||||||||||||||||||||||||||||||||||||
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Synonyms | Polygala section rhinotropis | Polygalarimulicola steyermark | ||||||||||||||||||||||||||||||||||||||||||||||||
Name authority | (S. F. Blake) J. R. Abbott: J. Bot. Res. Inst. Texas 5: 134. (2011) | (Steyermark) J. R. Abbott: J. Bot. Res. Inst. Texas 5: 135. (2011) | ||||||||||||||||||||||||||||||||||||||||||||||||
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