Opuntia tortispina |
Opuntia aureispina |
|
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plains pricklypear |
Rio Grande pricklypear |
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Habit | Shrubs, low, to 0.4 m, creeping from clumps, sometimes from thickened rootstocks. | Shrubs or trees, with short spiny trunks, erect, to 1(–1.5) m. Stem segments not disarticulating, light blue-green to yellow-green, flattened, circular to obovate, 8–12 × 8–12 cm, glaucous, ± tuberculate, glabrous; areoles 6–8 per diagonal row across midstem segment, oblong, 4–5 × 1–3 mm; wool brown to blackish. |
Stem | segments not easily detached, pale green to deep green, graying with age, wrinkled when stressed, flattened, broadly obovate to ovate, 6.5–15 × 4–10 cm, tuberculate, glossy, glabrous; areoles 6–9 per diagonal row across midstem segment, oval, obovate, or subcircular, 2.5–5 × 1.5–4 mm; wool tan, aging brown. |
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Spines | 1–9 on most areoles to only on distal 1/2 of stem segment, white to gray with pale brown tips and bases, sometimes brown throughout; central spines 1–3, all deflexed or 1–2 porrect or ascending, terete or flattened, occasionally spirally twisted, 25–70 mm; small spines (2–)3–6(–8) strongly deflexed, usually slender, even bristlelike, 5–15 mm. |
usually 4–12 per areole, evenly distributed on stem segments, spreading, bright yellow to orange, red-brown at extreme base, aging tan to blackish, not chalky white, acicular; major spines (1–)3–5(–6) per areole, sometimes flattened and/or curved, 20–60 mm; smaller spines 1–7 per areole, slender, to 20 mm. |
Glochids | forming a well developed adaxial tuft, yellow to brownish white, to 6 mm. |
well spaced in very narrow row encircling areole, subapical tuft not or poorly developed, yellow, unequal in length, to 5 mm. |
Flowers | inner tepals yellow to gold, commonly darker to red near base, broadly spatulate, 30–40 mm, apiculate; filaments usually pale yellow; anthers yellow; style whitish to pale green; stigma lobes greenish. |
inner tepals yellow with orange to red bases, obovate, 30–40 mm; filament yellow to pale green; anthers pale yellow; style yellow, sometimes basally pinkish; stigma lobes green. |
Fruits | purple-red, oval to broadly ovate, subspheric or short ovoid, bases not narrowed, 30 × 20–25 mm, fleshy, base not narrowed, glabrous, spineless or nearly so; umbilicus deep; areoles 18–30. |
green to reddish, turning tan, burlike, 30–40 × 20–25 mm, beginning fleshy, quickly drying, glabrous, bearing several rigid, yellow spines; areoles 12–25. |
Seeds | whitish to tan, irregularly shaped, flattened, 4–6 × 3–4 mm; girdle protruding 1–2 mm. |
tan, flattened, irregular in outline, 3–6 mm diam.; girdle protruding to 1 mm. |
2n | = 44, 66. |
= 22. |
Opuntia tortispina |
Opuntia aureispina |
|
Phenology | Flowering spring–early summer (Apr–Jul). | Flowering spring (May). |
Habitat | Grass-lands, pinyon-juniper-oak woodlands, sandy or shaley flats, rocky hills | Limestone desert flats, low hills |
Elevation | 1400-1800 m (4600-5900 ft) | 500-600 m (1600-2000 ft) |
Distribution |
CO; KS; NE; NM; OK; TX; WY |
TX; Mexico (Coahuila) |
Discussion | Opuntia tortispina is apparently of hybrid origin. It has intermediate character states from its putative parents, O. macrorhiza (fleshy and spineless fruits) and O. polyacantha (areoles with basal deflexed spines and barrel-shaped fruits). The spirally twisted spines, which the specific epithet implies, are not at all characteristic for this species. When O. tortispina and O. cymochila are considered conspecific, the former has priority, as first selected by N. L. Britton and J. N. Rose (1919–1923, vol. 1). One favored hypothesis as to the origins is that the O. humifusa-O. macrorhiza-O. pottsii complex spread across the United States from the east coast to Arizona. Opuntia polyacantha originated in north-central Mexico and spread northward. Tetraploid O. macrorhiza came into contact with the east flank of O. polyacantha and hybridized (probably repeatedly, even at present), producing the highly variable taxon referred to here as O. tortispina, which then spread eastward onto the plains. Opuntia tortispina has hexaploid members, presumably from unions of reduced and unreduced gametes. Those hexaploids apparently hybridize with hexaploid O. phaeacantha and add further to variation of O. tortispina. Many of these variations have been formally named or since treated as synonyms of O. macrorhiza. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Opuntia aureispina hybridizes with O. phaeacantha (= O. ×spinosibacca M. S. Anthony) and O. macrocentra (= O. ×rooneyi M. P. Griffith). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 4, p. 132. | FNA vol. 4. |
Parent taxa | Cactaceae > subfam. Opuntioideae > Opuntia | Cactaceae > subfam. Opuntioideae > Opuntia |
Sibling taxa | ||
Synonyms | O. cymochila, O. mackensenii, O. tortispina var. cymochila | O. macrocentra var. aureispina |
Name authority | Engelmann & J. M. Bigelow: Proc. Amer. Acad. Arts 3: 293. (1856) | (S. Brack & K. D. Heil) Pinkava & B. D. Parfitt: J. Arizona-Nevada Acad. Sci. 33: 150. (2001) |
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