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beavertail, beavertail cactus, beavertail pricklypear

erect pricklypear, nopal estricto, pest pricklypear

Habit Shrubs, forming clumps, 1–2(–3) segments tall, to 7–40 cm. Shrubs, sprawling or erect, to 2 m. Stem segments not disarticulating, green, flattened, narrowly elliptic or obovate, 10–25(–40) × 7.5–15(–25) cm, tuberculate, making margins appear scalloped between raised areoles, glabrous; areoles 3–5 per diagonal row across midstem segment, oval, 3–6.5 × 3.5 mm; wool dense, tan.
Stem

segments not disarticulating, blue- to yellow-green, sometimes tinged maroon-purple, flattened, spatulate to broadly obovate or subcircular, thick, 5–22(–35) × 2–13.5(–16) cm, nearly smooth, papillose to puberulent (rarely glabrous);

areoles 4–16(–19) per diagonal row across midstem segment, circular to elliptic, 3–5 × 3 mm;

wool white to tan, aging gray.

Spines

0(–8) per areole, when present, usually in distal areoles, spreading, yellow, straight, acicular, 5–25 mm.

0–11 per areole, in nearly all areoles to only in some marginal areoles or absent, spreading in all directions, yellow, aging brown, straight or curving, the longest stout, oval in cross section, 12–40(–60) mm, not markedly barbed.

Glochids

numerous, nearly filling areoles, yellow to red-brown or dark brown, to 3 mm.

inconspicuous, few to many in crescent at adaxial edge of areole, yellow, aging brown, often incurved, subequal to increasing in length toward adaxial edge of areole, to 4 mm.

Flowers

inner tepals pink to magenta throughout (rarely white), 25–40 mm;

filaments red-magenta (rarely pale);

anthers yellowish;

style white to pink;

stigma lobes white to cream.

inner tepals light yellow throughout, 25–30 mm;

filaments yellow;

anthers yellow;

style and stigma lobes yellowish.

Fruits

maturing tan, 20–40 × 15–23 mm, dry at maturity, puberulent, spineless (except in var. treleasei);

umbilicus 5–12 mm deep;

areoles 24–76.

purplish throughout, stipitate, ellipsoid or barrel-shaped, 40–60 × 25–30(–40) mm, juicy, spineless;

areoles 6–10.

Seeds

yellowish to tan, ± subspheric but angular, thick, 6.5–9 × 6.5–7 mm, sides smooth or bearing 1–3 depressions;

girdle protruding to 1 mm.

tan, subcircular, 4–5 × 4–4.5 mm, with slightly irregular surface;

girdle protruding to 1 mm.

2n

= 44 (cultivated), 66.

Opuntia basilaris

Opuntia stricta

Phenology Flowering spring–summer (Feb–Jul).
Habitat Coastal sand dunes, hammocks, edges of maritime forests, shell middens
Elevation 0 m (0 ft)
Distribution
from FNA
AZ; CA; NV; UT; n Mexico
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; FL; GA; SC; TX; Mexico; Central America; West Indies [South Africa (introduced); Australia (introduced)]
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 4 (4 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Opuntia stricta hybridizes with O. engelmannii (apparently var. lindheimeri) forming O. ×alta Griffiths (as species) along the coast of southeastern Texas and adjacent Louisiana. The hexaploid hybrid is arborescent to 3 m; it has stem segments subcircular to oblong-ovate, with a glochid pattern intermediate of the putative parents, all yellow spines, and light green stigma lobes.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Stem segments bearing spines in at least several of distal areoles
var. treleasei
1. Stem segments essentially spineless (rarely 1-few per stem segment)
→ 2
2. Stem segments broadly obovoid to subcircular, erect; areoles (8-)10-16(-19) per diagonal row across midstem segment
var. basilaris
2. Stem segments spatulate to elongate, oblong, usually decumbent; areoles 4-8(-9) per diagonal row across midstem segment
→ 3
3. Stem segments spatulate, apex rounded; areoles 4-8(-9) per diagonal row across midstem segment; Arizona, Utah.
var. longiareolata
3. Stem segments oblong to narrowly spatulate to subcylindric, apex truncate to rounded; areoles 4-6(-7) per diagonal row across midstem segment; California
var. brachyclad
Source FNA vol. 4, p. 144. FNA vol. 4, p. 133.
Parent taxa Cactaceae > subfam. Opuntioideae > Opuntia Cactaceae > subfam. Opuntioideae > Opuntia
Sibling taxa
O. aciculata, O. atrispina, O. aurea, O. aureispina, O. chisosensis, O. chlorotica, O. cubensis, O. ellisiana, O. engelmannii, O. ficus-indica, O. fragilis, O. humifusa, O. littoralis, O. macrocentra, O. macrorhiza, O. microdasys, O. oricola, O. phaeacantha, O. pinkavae, O. polyacantha, O. pottsii, O. pusilla, O. rufida, O. santa-rita, O. stricta, O. strigil, O. tortispina, O. triacantha, O. ×columbiana, O. ×curvispina, O. ×occidentalis, O. ×spinosibacca, O. ×vaseyi
O. aciculata, O. atrispina, O. aurea, O. aureispina, O. basilaris, O. chisosensis, O. chlorotica, O. cubensis, O. ellisiana, O. engelmannii, O. ficus-indica, O. fragilis, O. humifusa, O. littoralis, O. macrocentra, O. macrorhiza, O. microdasys, O. oricola, O. phaeacantha, O. pinkavae, O. polyacantha, O. pottsii, O. pusilla, O. rufida, O. santa-rita, O. strigil, O. tortispina, O. triacantha, O. ×columbiana, O. ×curvispina, O. ×occidentalis, O. ×spinosibacca, O. ×vaseyi
Subordinate taxa
O. basilaris var. basilaris, O. basilaris var. brachyclad, O. basilaris var. longiareolata, O. basilaris var. treleasei
Synonyms Cactus strictus, O. dillenii, O. inermis, O. stricta var. dillenii
Name authority Engelmann & J. M. Bigelow: Proc. Amer. Acad. Arts 3: 298. (1856) (Haworth) Haworth: Syn. Pl. Succ., 191. (1812)
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