Epithelantha micromeris var. micromeris

Common names: Common button cactus
Treatment appears in FNA Volume 4. Treatment on page 240. Mentioned on page 238.

Plants usually unbranched, appearing ashy gray and rough in general aspect. Stems short cylindric to ovoid, (1.3–)2–3.8 cm diam. Spines 20–35(–40) per areole, in 1–3 series, mature lateral spine clusters grayish or purplish white with brown bases, collectively appearing as brown spot at center of each spine cluster, 4–5(–7) mm diam.; longest intact spines near apex of stem 3–12 mm; worn spines 1–3 mm. Flowers partially obscured by longer spines at stem apex, 6–8.5 × 3–4.6 mm; inner tepals 5–8 per flower, (1–)2.5–3.5 × 1–2 mm; stamens 15–16. 2n = 22.


Phenology: Flowering late winter–early spring (Feb–Apr); fruiting late spring–early summer (Apr–Jun).
Habitat: Woodlands, deserts, grasslands, crevices, coarse gravel, cliffs, sedimentary (rarely igneous) substrates
Elevation: 500-1800 m

Discussion

Epithelantha micromeris var. micromeris has the smallest flowers of any cactus species in the flora. Unlike other taxa in this genus, it is autogamous. No hybrids with E. bokei have been found. The spines of var. var. micromeris are never as strongly appressed as on E. bokei except on sexually immature plants less than 15 mm in diameter; those immature plants have the fewest spines.

Selected References

None.

Lower Taxa

None.
Allan D. Zimmerman +  and Bruce D. Parfitt +
(Engelmann) F. A. C. Weber ex Britton & Rose +
Mammillaria micromeris +
Common button cactus +
Ariz. +, N.Mex. +  and Tex. +
500-1800 m +
Woodlands, deserts, grasslands, crevices, coarse gravel, cliffs, sedimentary (rarely igneous) substrates +
Flowering late winter–early spring (Feb–Apr) +  and fruiting late spring–early summer (Apr–Jun). +
Illustrated +
Epithelantha micromeris var. micromeris +
Epithelantha micromeris +
variety +