Hamatocactus

Britton & Rose

Cact. 3: 104, figs. 110–114. 1922.

Common names: Twisted-rib cactus
Etymology: Latin hamatus, hooked, in reference to the hooked central spines, and Cactus, an old genus name
Treatment appears in FNA Volume 4. Treatment on page 218. Mentioned on page 98, 207, 208.

Plants erect, unbranched or branched in basal portion, not deep-seated in substrate. Roots diffuse. Stems unsegmented, bright deep green, hemispheric when young, becoming spheric or ovoid to cylindric, 3.6–12 (–20) × 4.5–12 cm, glabrous; ribs 13, spiraling or vertical, slender, crests sinuate, sharp, not interrupted or undulate, narrow; areoles circular or, on older parts of stem, elliptic to ovate, adaxially elongated into short areolar grooves; areolar glands golden, darker with age, cylindric or peglike; cortex and pith firm, not mucilaginous. Spines 11–20 per areole, not obscuring stems, yellowish, whitish, or reddish-brown, acicular (rarely central spine flattened), longest spines 12–38 mm; radial spines 10–19 per areole, straight or slightly curved toward stem, longest spines 11–32 mm; central spines 1 per areole, porrect, hooked, terete (rarely flattened). Flowers diurnal, near stem apex, at adaxial edge of areoles or at axillary ends of short areolar grooves, widely funnelform, 3.7–7 × 4–7 cm; outer tepals finely fringed; inner tepals yellow (to ivory) with red bases, 20–25 × 6–9 mm, margins entire, toothed, or lacerate; ovary scaly, hairless, spineless; stigma lobes 5–11, pale-yellow to orangish, 3–7 mm. Fruits indehiscent or eventually dehiscent by vertical slits, bright red, spheric or nearly so, ca. 10 × 8–13 mm, fleshy, with 15 or fewer whitish, broad fringed, naked, spineless scales; floral remnant persistent. Seeds black, obovoid, usually 1–1.4 × 0.8–1 mm, minutely papillate; testa cells weakly convex, nearly flat toward proximal end of seed. x = 11.

Distribution

Arid regions, sw United States, Mexico

Discussion

Species 1.

Hamatocactus has been submerged in Ferocactus or Thelocactus by various authors and grouped with Glandulicactus by others.

Selected References

None.

"elongated" is not a number.

... more about "Hamatocactus"
cushionlike +
darker +  and golden +
peglike +  and cylindric +
deciduous +  and persistent +
elliptic +  and ovate +
Allan D. Zimmerman +  and Bruce D. Parfitt +
Britton & Rose +
hardened +
triangular +
terete +  and hooked +
proliferating +
flattened +  and cylindric +
Twisted-rib cactus +
not mucilaginous +
not interrupted +
undulate +, sharp +  and sinuate +
Arid regions +, sw United States +  and Mexico +
not separating +
Latin hamatus, hooked, in reference to the hooked central spines, and Cactus, an old genus name +
3.7 cm37 mm <br />0.037 m <br /> (7 cm70 mm <br />0.07 m <br />) +
15 cm150 mm <br />0.15 m <br /> (30 cm300 mm <br />0.3 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (15 cm150 mm <br />0.15 m <br />) +
dehiscent +  and indehiscent +
persistent +, long +  and deciduous +
nearly +  and spheric +
0.8 cm8 mm <br />0.008 m <br /> (1.3 cm13 mm <br />0.013 m <br />) +
2 cm20 mm <br />0.02 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
deciduous +  and persistent +
rudimentary +
flat +  and terete +
nearly +  and microscopic +
0 cm0 mm <br />0 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
tuberculate +
fluted;spheric;depressed-spheric or club-shaped +
1.1 cm11 mm <br />0.011 m <br /> (3.2 cm32 mm <br />0.032 m <br />) +
lacerate +, toothed +  and entire +
deciduous +  and persistent +
not mucilaginous +
ridgelike +  and nipple--shaped +
slender +
spineless +  and naked +
fringed +
arillate +  and strophiolate +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.14 cm1.4 mm <br />0.0014 m <br />) +
papillate +
obovoid +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
reddish-brown +, whitish +  and not yellowish +
curved +  and straight +
deciduous +  and persistent +
10 (?) +  and 19 (?) +
acicular +
hard +  and rigid +
decurrent +
unsegmented +
3.6cm;12cm +
ovoid +  and cylindric +
succulent +
4.5cm;12cm +
pale-yellow +  and orangish +
tuberculate +
adventitious +
tuberlike +
epipetric +  and epiphytic +
Hamatocactus +
Cactaceae subfam. Cactoideae +
dull +  and glossy +
branched +  and unbranched +
epiphytic;epiphytic;epiphytic +
not deep-seated +
barrel-shaped +  and spheric +