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Pediocactus nigrispinus

black-spine snowball cactus, Columbia Plateau cactus, dark-spine ball cactus, snowball cactus

gypsum cactus, Siler pincushion cactus, Siler's pincushion cactus

Habit Plants typically branched. Plants few branched or unbranched.
Stems

depressed-ovoid to elongate-ovoid, 5–30 × 5–15 cm;

areoles oval, villous.

depressed-ovoid or occasionally elongate-cylindric, 5–15(–25) × 6–11.5 cm;

areoles circular to pyriform, villous to lanate.

Spines

smooth, hard and rigid, distinguishable as radial and central;

radial spines 10–30 per areole, spreading at right angles to tubercles, nearly straight, white to dull reddish brown, 8–20 mm;

central spines 6–12 per areole, widely spreading or nearly erect, reddish brown to nearly black, rigid, straight or slightly curved, base yellow or cream, 15–35 mm, less than 1 mm diam. at base.

distinguishable as radial and central: radial spines 11–15 per areole, white, 11–21 mm;

central spines 3–7 per areole, nearly porrect, brownish black aging to pale gray or white, straight or slightly curving at tips, 13–30 × 1 mm at base.

Flowers

1–3.5 × 2.5–5 cm;

scales and outer tepals of flower tube minutely toothed, laciniate, or entire and undulate;

outer tepals with greenish brown midstripes, oblong-cuneate, 12–25 × 4.5–9 mm;

inner tepals white, pink, magenta, yellow, or yellow-green, 19–27 × 5–10 mm.

0.8–2.2 × 2–3 cm;

scales long fringed;

outer tepals brown with white margins, long fringed, 9–15 × 3–4.5 mm;

inner tepals yellow with purple veins, 15–20 × 4.5–6 mm.

Fruits

green tinged with red, drying reddish brown, short cylindric, 6–11 × 5–10 mm.

greenish yellow, short cylindric, 12–15 × 6–9 mm.

Seeds

gray to black, 2–3 × 1.5–2 mm, papillate but not rugose.

gray to nearly black, 3.5–5 × 3–3.5 mm, papillate and rugose.

Pediocactus nigrispinus

Pediocactus sileri

Phenology Flowering spring. Flowering spring.
Habitat Great Basin desert scrub, sagebrush, grasslands, coniferous forests Rounded hills in gypsum clay and sandy soils of Moenkopi Formation, Great Basin desert scrub
Elevation 400-2000 m (1300-6600 ft) 900-1600 m (3000-5200 ft)
Distribution
from FNA
ID; OR; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; UT
[BONAP county map]
Discussion

No known morphologic character supports the taxonomic recognition of infraspecific taxa within Pediocactus nigrispinus. Characteristics used to distinguish the three described subspecies almost completely overlap. Pediocactus nigrispinus has been referred to P. simpsonii var. robustior (J. M. Coulter) L. D. Benson, which remains well within the range of variation for P. simpsonii. An unpublished study by J. M. Porter et al. of noncoding chloroplast DNA sequences shows P. simpsonii is less closely related to P. nigripsinus than to P. knowltonii, P. winkleri, and P. despainii.

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

Of conservation concern.

Pediocactus sileri stems tend to develop a basal thatch of spines that anchor it to the fine, gypsum-rich soil. This species is endemic to a narrow strip along the Arizona-Utah border.

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

Source FNA vol. 4. FNA vol. 4, p. 212.
Parent taxa Cactaceae > subfam. Cactoideae > Pediocactus Cactaceae > subfam. Cactoideae > Pediocactus
Sibling taxa
P. bradyi, P. despainii, P. knowltonii, P. paradinei, P. peeblesianus, P. sileri, P. simpsonii, P. winkleri
P. bradyi, P. despainii, P. knowltonii, P. nigrispinus, P. paradinei, P. peeblesianus, P. simpsonii, P. winkleri
Synonyms P. simpsonii var. nigrispinus, P. nigrispinus var. beastonii, P. nigrispinus subsp. beastonii, P. nigrispinus subsp. puebloensis Echinocactus sileri, Utahia sileri
Name authority (Hochstätter) Hochstätter: Succulenta (Netherlands) 71: 99. (1992) (Engelmann ex J. M. Coulter) L. D. Benson: Cact. Succ. J. (Los Angeles) 33: 53. (1961)
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