Opuntia phaeacantha
Opuntia macrorhiza
brown-spine prickly-pear, dark-spine prickly pear, Mojave prickly pear, tulip prickly pear
grassland pricklypear, plains prickly pear, plains twistspine pricklypear, twistspine pricklypear, western pricklypear
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.
(0–)2–8 per areole, at most areoles to only distal 1/4 of stem segment, or essentially absent, brown to white, straight, curved, or spirally twisted;
major central spines deflexed or spreading, brown to red-brown (to blackish), or partly to wholly gray to tan, subulate, usually flattened near base, 30–80 mm;
abaxial spines usually 1–3, deflexed, white, flattened, shorter, to 20 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.
dense in crescent at adaxial edge of areole and subapical tuft, tan to red-brown, to 5 mm.
in dense tuft, pale yellow, tan to red-brown, aging brown, to 5 mm.
inner tepals yellow with red basal portions (rarely entirely pink to red), 30–40 mm;
filaments greenish basally, pale yellow to white distally;
anthers yellow;
style white;
stigma lobes green to yellow-green.
inner tepals yellow with red basal portions, 25–40 mm;
filaments pale yellow;
anthers yellow;
style white;
stigma lobes cream to yellowish.
wine red to purple, with greenish flesh (sometimes reddish and ± juicy), not long stipitate, obovate to barrel-shaped, 30–50 × 20–30 mm, fleshy, glabrous, spineless;
areoles 18–24.
green to yellowish to dull red, stipitate, elongate-obovoid, 25–40 × 15–28 mm, fleshy, glabrous;
areoles 16–28.
tan, subcircular, 4–5 mm diam., evidently notched, warped;
girdle protruding 1 mm.
tan, subcircular, 4–5 mm, thickish, warped;
girdle broad, protruding to 0.5 mm.
= 66.
= 44.
Opuntia phaeacantha
Opuntia macrorhiza
Much of the material formerly assigned to varieties of Opuntia phaeacantha has been segregated as O. engelmannii. Various combinations of overlapping character states make separation of O. phaeacantha var. major from var. phaeacantha impractical. Presumably var. major comprises sprawling to erect shrubs with obovate stem segments bearing usually few darker colored spines (usually one to three) per areole, in the distal half of the stem segment or less, whereas plants of var. phaeacantha are trailing shrubs with narrowly obovate stem segments bearing more spines (usually three to ten) per areole throughout most to all of the stem segment. Recently some workers have applied O. camanchica Engelmann & Bigelow to those plants with the very dark colored spines and merged vars. major and phaeacantha. Distinctions among taxa are further blurred by hybridization of O. phaeacantha with O. engelmannii, yielding several named and unnamed hybrids, including O. wootonii Griffiths. Morphologic and genetic analyses of the populations are needed before correct names can be assigned to many of these plants with confidence.
Opuntia phaeacantha also hybridizes with O. aureispina (forming O. ×spinosibacca), O. ficus-indica, and O. littoralis (forming O. ×vaseyi), and members of the O. polyacantha complex, particularly near the regions of Grand Canyon and Four Corners.
(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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