Opuntia tortispina |
Opuntia chisosensis |
|
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plains pricklypear |
Chisos Mountain pricklypear |
|
Habit | Shrubs, low, to 0.4 m, creeping from clumps, sometimes from thickened rootstocks. | Shrubs, erect, to 1 m. Stem segments not easily detached, bluish to gray-green, flattened, circular to broadly obovate, 15–30 × 12–25 cm, nearly smooth, glabrous; areoles 5–7 per diagonal row across midstem segment, elliptic to obovate, 3–8 × 2–6 mm; wool tan, aging 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. |
1–5 per areole, spreading, yellow to orange, tipped yellow, darkening with age (at higher elevations), or dark red-brown (lower elevations), ± acicular, longest 20–67 mm, terete to flattened near base, often curved. |
Glochids | forming a well developed adaxial tuft, yellow to brownish white, to 6 mm. |
widely spaced, in crescent at adaxial margin of areole, partially encircling areoles, and in poorly developed subapical tuft, yellow, of irregular lengths, tending to elongate towards bases of areoles, to 4 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 pale yellow to buff throughout, to 25–30 mm; filaments pale green; anthers and style yellow; 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. |
reddish purple, ellipsoid to spheric, barrel-shaped, 33–45 × 40–50 mm, juicy, base not or little tapered, glaucous, spineless; areoles 16–20, mostly near apex. |
Seeds | whitish to tan, irregularly shaped, flattened, 4–6 × 3–4 mm; girdle protruding 1–2 mm. |
yellow to tan, 3.5–4.5 × 3–4 mm diam.; girdle protruding to 1 mm. |
2n | = 44, 66. |
= 22. |
Opuntia tortispina |
Opuntia chisosensis |
|
Phenology | Flowering spring–early summer (Apr–Jul). | Flowering late spring (May). |
Habitat | Grass-lands, pinyon-juniper-oak woodlands, sandy or shaley flats, rocky hills | Pine-oak and mixed conifer forests, grasslands |
Elevation | 1400-1800 m (4600-5900 ft) | 1600-2200 m (5200-7200 ft) |
Distribution |
CO; KS; NE; NM; OK; TX; WY |
TX |
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 chisosensis is local in the Chisos Mountains in western Texas, and it has been reported from Sierra del Carmen in Coahuila, Mexico by Ferguson, but this has not been confirmed by the author. It is perhaps related to, or part of, the O. azurea Rose complex in northern Chihuahuan Desert of Mexico. (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. lindheimeri var. chisosensis |
Name authority | Engelmann & J. M. Bigelow: Proc. Amer. Acad. Arts 3: 293. (1856) | (M. S. Anthony) D. J. Ferguson: Cact. Succ. J. (Los Angeles) 58: 124. (1986) |
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