Sclerocactus papyracanthus

(Engelmann) N. P. Taylor

Bradleya 5: 94. 1987.

Common names: Grama-grass cactus paper-spined cactus toumeya
Basionym: Mammillaria papyracantha Engelmann Mem. Amer. Acad. Arts, n. s. 4: 49. 1849
Synonyms: Pediocactus papyracanthus (Engelmann) L. D. Benson Toumeya papyracantha (Engelmann) Britton & Rose
Treatment appears in FNA Volume 4. Treatment on page 205. Mentioned on page 197, 198, 203, 206, 207.

Stems unbranched, cylindric or obconic cylindric, 2–7.5(–8) × 1.2–2.5 cm; ribs not evident, tubercles prominent. Spines dense, obscuring stems; radial spines 5–10 per areole, white, straight, flat, (2–)3–5 × 0.3–0.6 mm; central spines 1(–4) per areole; abaxial central spine 1 per areole, whitish to tan or gray, straight, wavy, twisting, or curling, flat, flexible, papery, with obscure adaxial midrib, sometimes pointing upward and obscuring apex of plant, lacking hook, 15–45(–50) × 1–1.5 mm; lateral or adaxial central spines 0(–3) per areole, white to tan, (3–)20–40 × 0.5–1 mm. Flowers funnelform to narrowly campanulate, 2–2.5 × 1–2.5 cm; outer tepals with green-purple to red-brown midstripes and cream to white margins, cuneate-spatulate, usually 9–20 × 1–3 mm, finely toothed; inner tepals white with brown midstripes, largest tepals oblanceolate, 15–20 × 3.5–4.5 mm, apex acute to mucronate; filaments white to greenish yellow; anthers cream to pale yellow. Fruits indehiscent or irregularly dehiscent, green, subspheric, 4–6 × 3–5 mm, dry at maturity; scales few or none. Seeds black, 2.5–3 × 2–2.5 mm, shiny; testa with fine, rounded papillae.

Phenology: Flowering Apr–Jun.
Habitat: Desert grasslands, pinyon-juniper woodlands, Chihuahuan desert scrub
Elevation: 1500-2200 m


With long, flexuous, flattened spines and pale flowers, Sclerocactus papyracanthus is surprisingly cryptic in the field. There has been a long debate concerning its taxonomic placement. Chloroplast DNA analyses of J. M. Porter et al. (2000) unambiguously placed this species within Sclerocactus, a position first suggested based on morphologic evidence (K. D. Heil et al. 1981; C. Glass and R. A. Foster 1984).

Selected References


Lower Taxa

Kenneth D. Heil +  and J. Mark Porter +
(Engelmann) N. P. Taylor +
Mammillaria papyracantha +
Grama-grass cactus +, paper-spined cactus +  and toumeya +
Ariz. +, N.Mex. +  and Tex. +
1500-2200 m +
Desert grasslands, pinyon-juniper woodlands, Chihuahuan desert scrub +
Flowering Apr–Jun. +
Illustrated +  and Endemic +
Pediocactus papyracanthus +  and Toumeya papyracantha +
Sclerocactus papyracanthus +
Sclerocactus +
species +