Thelocactus bicolor var. bicolor

Illustrated
Synonyms: Thelocactus bicolor var. schottii (K. Schumann) F. M. Knuth Thelocactus bicolor var. tricolor
Treatment appears in FNA Volume 4. Treatment on page 218. Mentioned on page 215.

Plants few branched or unbranched, usually not deep-seated in substrate. Stems usually ovoid to cylindric at maturity, 7.5–18(–38) × 5–10(–13) cm, surface very poorly concealed to 1/2 hidden by spines; ribs 8–13, tubercles confluent into rounded ribs 15–25 mm wide; areoles spaced 8–20 mm apart along ribs. Spines red and white (older spines weather to ashy white); radial spines 9–18 per areole, longest spines 12–30 mm; adaxial (bladelike) spines 16–75(–100) × 1.5 mm; central spines (1–)4, longest spines terete to sharply angular, then abaxially keeled and adaxially flat to grooved, (13–)20–45(–60) × 0.4–1.5 mm, adaxial 3 like radials but larger. 2n = 22.


Phenology: Flowering (Feb–May)Jul–Sep.
Habitat: Chihuahuan desert scrub, Tamaulipan thorn scrub, sedimentary, igneous, and alluvial substrates
Elevation: 0-1200[-2000] m

Distribution

V4 407-distribution-map.gif

Tex., Mexico (Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Tamaulipas, Zacatecas).

Discussion

Thelocactus bicolor var. bicolor, in the strict sense, may be limited to Mexico; if so, then var. tricolor and/or var. schottii might deserve formal recognition.

Selected References

None.

Lower Taxa

None.
Allan D. Zimmerman +  and Bruce D. Parfitt +
(Galeotti ex Pfeiffer) Britton & Rose +
Echinocactus bicolor +
Tex. +, Mexico (Chihuahua +, Coahuila +, Durango +, Nuevo León +, San Luis Potosí +, Tamaulipas +  and Zacatecas). +
0-1200[-2000] m +
Chihuahuan desert scrub, Tamaulipan thorn scrub, sedimentary, igneous, and alluvial substrates +
Flowering (Feb–May)Jul–Sep. +
Bull. Torrey Bot. Clu b +
Illustrated +
Thelocactus bicolor var. schottii +  and Thelocactus bicolor var. tricolor +
Thelocactus bicolor var. bicolor +
Thelocactus bicolor +
variety +