Opuntia polyacantha |
Opuntia macrocentra |
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hair-spine prickly pear, panhandle prickly pear, plains prickly pear, starvation prickly-pear |
black-spine pricklypear, nopal violaceo, purple pricklypear |
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Habit | Shrubs, low, 10–25 cm, with ± prostrate branches. | Shrubs, erect to decumbent, to 1 m. Stem segments not easily detached, purple (particularly under stress) to green with purple near areoles and margins of stem segment, flattened, broadly obovate to subcircular, thickish, 7–20 × 6–18 cm; areoles 6–8(–10) per diagonal row across midstem segment, elliptic to circular, 3–7 × 2.5–5 mm; wool tan to whitish, aging black. | ||||||||||||||||
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. |
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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 or 1–15+ per areole, few and at distal areoles or many and on most areoles, usually erect to spreading, appearing unruly, sometimes deflexed, straight or curving, acicular, often flexible, subterete to flattened basally; longer ones reddish brown to ± black (rarely yellow to red in w Texas), or partly to wholly white, 30–120(–170) mm; reflexed spine rarely present, 1 in some areoles, short, whitish. |
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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. |
dense in crescent at adaxial edge of areole and well-developed subapical tuft, reddish yellow, aging brown, 2–3(–6) 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, obovate-apiculate, 25–40 mm; filaments and anthers yellowish; style cream; stigma lobes green. |
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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. |
red to purplish, obovoid to barrel-shaped, 25–40 × 20–23 mm, fleshy or ± juicy, glabrous, spineless; umbilicus 8–10 mm deep; areoles 22–44. |
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Seeds | tan to gray, flattened, warped, oblong to subcircular, 3–7 × 2–4 mm; girdle protruding 1–2 mm. |
yellowish, suborbicular to reniform, angled, 5–7 × 3.5–5 mm, sides flattened; girdle protruding 0.8–1.2 mm. |
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2n | = 22, 44. |
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Opuntia polyacantha |
Opuntia macrocentra |
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Phenology | Flowering spring (Mar–Jun). | |||||||||||||||||
Habitat | Desert uplands, grasslands, oak woodlands, sandy desert flats, rocky hills and valleys | |||||||||||||||||
Elevation | 900-1600 m (3000-5200 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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AZ; NM; TX; Mexico (Chihuahua, Coahuila, Sonora)
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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 macrocentra var. minor is represented by relatively short and compact shrubs with a glochid pattern of a dense crescent in the adaxial edge of the areoles like the species and a much taller tuft of spreading glochids. This variety, which grows along the western side of the Rio Grande in Big Bend, Texas, appears best interpreted as a tetraploid hybrid between tetraploid putative parents, Opuntia macrocentra and O. tortispina. (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. violacea, O. violacea var. castetteri, O. violacea var. macrocentra | ||||||||||||||||
Name authority | Haworth: Suppl. Pl. Succ., 82. (1819) | Engelmann: Proc. Amer. Acad. Arts 3: 292. (1856) | ||||||||||||||||
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