Opuntia polyacantha |
Opuntia macrorhiza |
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hair-spine prickly pear, panhandle prickly pear, plains prickly pear, starvation prickly-pear |
grassland pricklypear, plains prickly pear, plains twistspine pricklypear, twistspine pricklypear, western pricklypear |
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Habit | Shrubs, low, 10–25 cm, with ± prostrate branches. | Shrubs, forming clumps, 7.5–16 cm, sometimes from tuberlike rootstocks. | ||||||||||||||||
Stem | segments not easily detached, green, elliptic to narrowly to broadly obovate to circular, 4–27 × 2–18 cm, low tuberculate; areoles 4–14 per diagonal row across midstem segment, subcircular, 3–6 mm; wool tan to brown. |
segments not easily detached, dark dull green, often cross wrinkled when stressed, flattened, obovate to circular, 5–11 × 3.5–7.5 cm, fleshy (to flabby and cross wrinkled when stressed), tuberculate, glaucous; areoles 5–6(–8) per diagonal row across midstem segment, oval to subcircular, 2–4 mm diam.; wool tan. |
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Spines | at all or only distal areoles of stem segment, terete to flattened, stout to acicular to bristlelike, straight to curling, of 1 or 2 kinds; if 1 kind: 0–18 per areole, spreading and curling in various directions, sometimes straight, erect, ascending to deflexed, yellow to dark brown to black, turning gray, pink-gray to gray-brown, longest (35–)40–90(–185) mm; if ± 2 kinds: major spines (0–)1–5, reflexed to porrect, yellow-brown to brown to gray, longest 20–150 mm; minor spines (0–)5–11, deflexed, white to white-gray, longest 4–16 mm. |
(0–)1–4 per areole, usually in distal areoles, erect to spreading, white to red-brown, acicular, straight, terete or 1 flattened, ± stout (0.5 mm diam. at base), longest to 60 mm. |
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Glochids | inconspicuous, in narrow, tidy crescent at adaxial edge of areole or in broad, brushy crescent and tuft, yellow to reddish, aging brown, to 10 mm. |
in dense tuft, pale yellow, tan to red-brown, aging brown, to 5 mm. |
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Flowers | inner tepals yellow to magenta throughout, 25–40 mm; filaments white, yellow, or red to magenta (flowers may superficially appear bicolored); anthers yellow; style white to pale pink; stigma lobes green. |
inner tepals yellow with red basal portions, 25–40 mm; filaments pale yellow; anthers yellow; style white; stigma lobes cream to yellowish. |
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Fruits | tan to brown, ± cylindric, 15–45 × 12–25 mm, dry at maturity, glabrous, sometimes burlike; areoles 10–33, each or only distal areoles bearing 3–16 spines, 4–20 mm. |
green to yellowish to dull red, stipitate, elongate-obovoid, 25–40 × 15–28 mm, fleshy, glabrous; areoles 16–28. |
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Seeds | tan to gray, flattened, warped, oblong to subcircular, 3–7 × 2–4 mm; girdle protruding 1–2 mm. |
tan, subcircular, 4–5 mm, thickish, warped; girdle broad, protruding to 0.5 mm. |
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2n | = 44. |
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Opuntia polyacantha |
Opuntia macrorhiza |
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Phenology | Flowering late spring (May–Jun). | |||||||||||||||||
Habitat | Plains, chaparral, grassy woodlands, coniferous forests, sandy to loamy soils | |||||||||||||||||
Elevation | 100-2300 m (300-7500 ft) | |||||||||||||||||
Distribution |
AZ; CA; CO; ID; KS; MT; ND; NE; NM; NV; OK; SD; TX; UT; WY; AB; SK; n Mexico
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AR; AZ; CO; KS; MO; NM; OK; TX; UT; Mexico (Chihuahua)
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Discussion | Varieties 5 (5 in the flora). Populations of Opuntia polyacantha with spines few or absent (especially var. hystricina) were the basis for several names including O. juniperina, O. utahensis, and O. rhodantha. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Opuntia macrorhiza hybridizes with the hexaploid O. engelmannii (apparently var. lindheimeri) forming the pentaploid O. ×edwardsii V. E. Grant & K. A. Grant. This hybrid is a small subshrub, 20–40 cm, with a mixture of widely spaced, unequal glochids and closely spaced, shorter glochids. Its major spines are gray, and its tepals are yellow or yellow with red bases. Those characteristics are similar to one parent or the intermediate of the two putative parents reported from Blanco and Guadalupe counties, central Texas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 4. | FNA vol. 4. | ||||||||||||||||
Parent taxa | Cactaceae > subfam. Opuntioideae > Opuntia | Cactaceae > subfam. Opuntioideae > Opuntia | ||||||||||||||||
Sibling taxa | ||||||||||||||||||
Subordinate taxa | ||||||||||||||||||
Synonyms | Cactus ferox, Tunas polyacantha | O. compressa var. macrorhiza, O. mesacantha var. acrorhiza | ||||||||||||||||
Name authority | Haworth: Suppl. Pl. Succ., 82. (1819) | Engelmann: Boston J. Nat. Hist. 6: 206. (1850) | ||||||||||||||||
Web links |
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