Opuntia basilaris, Beavertail Cactus

Opuntia basilaris ramosa
Opuntia basilaris ramosa

Engelmann & Bigelow, Proceedings of the American Academy of Arts and Sciences 3: 298, 1856

Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Herbarium; Holotype (O. basilaris brachyclada); Herbarium (O. basilaris brachyclada); Herbarium (O. basilaris brachyclada); Herbarium (O. basilaris brachyclada); Isolectotype (O. basilaris ramosa); Holotype (O. basilaris ramosa); Herbarium (O. basilaris heilii); Herbarium (O. basilaris heilii); Herbarium (O. basilaris heilii); Isolectotype (O. basilaris woodburyi); Holotype (O. humistrata); Herbarium (O. basilaris treleasei); Holotype (O. basilaris whitneyana); Painting; Painting; Painting

Original Description

What is Opuntia basilaris?

Shrubs: Dense, clumping plants about 15–30 cm tall and 30–100 cm across. Cladodes: Blue-green to gray-green, often purplish in drought or cold; commonly wedge-shaped, obovate, or fan-shaped (sometimes oval or elongate-obovate), (7)15–17(22) cm long. Areoles: Slightly sunken. Glochids: Numerous and persistent; plants spineless. Flowers: Showy, magenta, typically 7–8 cm across. Filaments: Red. Anthers: Yellow. Styles: White to pinkish-white. Stigmas: White. Fruits: Dry at maturity. Seeds: Large, thick, often angular to subspherical, approximately 6.5–9 × 6.5–7 mm.

Other Notes

  • Infraspecific taxa currently recognized here include:

    • Opuntia basilaris var. basilaris — the autonym and most common variety

    • Opuntia basilaris var. brachyclada

    • Opuntia basilaris var. longiareolata

    • Opuntia basilaris var. ramosa

    • Opuntia basilaris var. treleasei

Britton and Rose described additional varieties such as albiflora, coerulea, and nanna, which are not recognized here. O. basilaris var. basilaris is by far the most commonly encountered variety. Except for var. treleasei, all varieties are spineless. O. woodburyi was formerly treated as a variety of O. basilaris but is considered here a distinct species due to its octaploid chromosome number; additional study would be welcome.

Native Americans traditionally used O. basilaris medicinally (Anderson, 2001). The cactus contains 3,4-dimethoxyphenethylamine, a compound chemically related to dopamine and mescaline, which may contribute to its effects.

O. basilaris is favored in cultivation for its distinctive form, pad coloration, and vibrant flowers; some high-elevation clones exhibit notable cold hardiness.

For more information, see:

Shaw et al., 2019: Tucson area Opuntia, the prickly pears
Majure et al., 2023: Beavertail cactus and relatives (Xerocarpa clade)

4 thoughts on “Opuntia basilaris, Beavertail Cactus”

  2. Joseph

    There are 2 types of Opuntia fruits.

    Some are juicy when ripe, like a berry.
    Some are dry when ripe, like a rattle.

    Dry fruit refers to those types that produce a rattle type fruit.

    Juicy fruits are by far the most common.

  3. Shawnee Giles

    I have inherited a collection of basilaris. I am having difficulty telling the varieties apart. Some have names attached to them but I’m not sure they are correct. Is there a printed paper or photos describing with more detail how to tell each one apart?

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