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Pediocactus nigrispinus

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

Knowlton's miniature cactus, Knowlton's minute cactus

Habit Plants typically branched. Plants branched or unbranched.
Stems

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

areoles oval, villous.

globular to short cylindric, 0.7–5.5 × 1–3 cm;

areoles circular, villous.

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.

smooth, relatively hard, all radial, mostly 18–26 per areole, spreading, recurved, or somewhat pectinate, reddish tan, pink, or white, 1–1.5 mm, canescent.

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.

1–3.5 × 1–2.5 cm;

scales and outer tepals essentially entire, often undulate;

outer tepals with brownish midstripes to 1.5 mm wide, 4–17 × 4–6 mm;

inner tepals pink, oblanceolate, 8–25 × 3–8 mm.

Fruits

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

green, drying reddish tan, turbinate,4 × 3 mm.

Seeds

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

black, 1.5 × 1–1.2 mm, papillate but not rugose.

Pediocactus nigrispinus

Pediocactus knowltonii

Phenology Flowering spring. Flowering spring.
Habitat Great Basin desert scrub, sagebrush, grasslands, coniferous forests Gravel pavements in pinyon-juniper woodlands with mixed sagebrush
Elevation 400-2000 m (1300-6600 ft) 2000 m (6600 ft)
Distribution
from FNA
ID; OR; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
NM
[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 knowltonii is the smallest and rarest member of the genus. The species is very closely related to P. simpsonii; chloroplast DNA sequence analysis provides support that it represents a recent developmental mutation within P. simpsonii (J. M. Porter et al. unpubl.).

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

Source FNA vol. 4. FNA vol. 4.
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. nigrispinus, P. paradinei, P. peeblesianus, P. sileri, P. simpsonii, P. winkleri
Synonyms P. simpsonii var. nigrispinus, P. nigrispinus var. beastonii, P. nigrispinus subsp. beastonii, P. nigrispinus subsp. puebloensis P. bradyi var. knowltonii, P. simpsonii var. knowltonii
Name authority (Hochstätter) Hochstätter: Succulenta (Netherlands) 71: 99. (1992) L. D. Benson: Cact. Succ. J. (Los Angeles) 32: 193. (1960)
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