Echinocactus

Link & Otto

Verh. Vereins Beförd. Gartenbaues Königl. Preuss. Staaten 3: 420. 1827.

Common names: Barrel cactus eagle-claw cactus echinocactus
Etymology: Greek echinos, hedgehog, an d Cactus, an old genus name
Synonyms: Homalocephala Britton & Rose
Treatment appears in FNA Volume 4. Treatment on page 188. Mentioned on page 97, 207.

Plants erect, branched or unbranched, forming compact mounds of 30+ branches, not deep-seated in substrate (or deep-seated in E. texensis and, if plants immature or at high altitude, in E. horizonthalonius). Roots diffuse or short taproots. Stems unsegmented, gray-blue, gray-green, yellow-green, or grass green, flat-topped spheric to short cylindric, 4–40 (–45) [–250] × 8–30 [–80] cm, apical region appearing copiously woolly (shortly velvety in E. texensis) [glabrous]; ribs (7–) 8–27 [–60+], very prominent, straight (or only slightly undulate), sometimes helically curving around stems, broadly rounded to nearly keeled, rib crests uninterrupted or ± constricted between areoles; areoles widely spaced or confluent with age, nearly circular to oblong, with fertile portion as short, broad adaxial prolongation confluent with spine cluster; areolar glands absent; cortex and pith hard, not mucilaginous. Spines (5–) 7–19 per areole, straw colored, pink, red, gray, tan, or brown, conspicuously annulate-ridged, rigid, stiff; radial spines 5–14 per areole, straight to curved, 2–5 cm; central spines 1–4 per areole, straight to curved, terete, flattened, or abaxially ridged. Flowers diurnal, near stem apex, near adaxial edges of short adaxial extensions of areoles, broadly funnelform to nearly salverform (more narrowly funnelform in E. texensis); outer tepals margins entire, apically spinose; inner tepals yellow or pink to magenta, 2.4–3.2 × 0.3–1.5 cm, margins entire, serrate, toothed, or erose; ovary scaly, spineless, copiously woolly, with white or pale tan hairs from areoles hiding ovary and flower tube at anthesis; scales 8–60, margins entire or fimbriate, spine-tipped; stigma lobes 6–14 (–17), yellow, pink, or olive, 1–4.5 mm. Fruits either indehiscent or rupturing irregularly, or tardily dehiscent through basal abscission pore, whitish tan to pinkish (bright red in E. texensis), spheric to ovoid or ovoid-cylindric, 10–50 × 10–40 [–100] mm, usually nearly dry (strongly succulent in E. texensis), many scaled; axils of scales copiously woolly (wool hiding surface of fruits except in E. texensis), spineless, distal scales spine-tipped; pulp red; floral remnant persistent. Seeds reddish-brown to black, spheric, or subreniform to obovoid, 2.4–4.7 mm, shiny or dull; testa cells convex or flat. x = 11.

Distribution

sw United States, Mexico

Discussion

Species 6 (3 in the flora).

With the exception of the much-branched Echinocactus polycephalus, species of Echinocactus in the flora area are almost never branched, and will die instead of producing a lateral bud when the apex is injured. Smaller than normal fruits of Echinocactus are usually aborted and hollow as the result of infestation by insect larvae (M. Chamberland, pers. comm.).

Selected References

None.

Key

1 Inner tepals yellow; plants many branched (except in very young adults); w Arizona, s Nevada, se California, Mexico Echinocactus polycephalus
1 Inner tepals pink, magenta, or proximally red and distally pink; plants unbranched (rarely few branched); c to s Arizona, New Mexico, Texas, Mexico > 2
2 Ribs (7-)8(-9), crests broadly rounded, never keeled; stems flat-topped or hemispheric to stoutly cylindric; fruit surfaces hidden by abundant wool at maturity; spines and bract tips glabrous (use lens) Echinocactus horizonthalonius
2 Ribs 13-27, crests narrow, ± keeled; stems flat-topped to hemispheric; fruit surfaces exposed at maturity, bright red; spines and bract tips densely puberulent with ± matted, strap-shaped, unicellular hairs (use at least 8× lens) Echinocactus texensis
... more about "Echinocactus"
cushionlike +
confluent +  and spaced +
circular to linear +
deciduous +  and persistent +
nearly circular +  and oblong +
Allan D. Zimmerman +  and Bruce D. Parfitt +
Link & Otto +
hardened +
triangular +
straight +  and curved +
ridged +, flattened +  and terete +
proliferating +
flattened +  and cylindric +
Barrel cactus +, eagle-claw cactus +  and echinocactus +
not mucilaginous +
sw United States +  and Mexico +
not separating +
Greek echinos, hedgehog, an d Cactus, an old genus name +
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 />) +
4 cm40 mm <br />0.04 m <br /> (10 cm100 mm <br />0.1 m <br />) +
whitish tan;pinkish +
indehiscent +  and dehiscent +
persistent +, long +  and deciduous +
10mm;50mm +
spheric +  and ovoid or ovoid-cylindric +
dry +, fleshy +  and juicy +
1 cm10 mm <br />0.01 m <br /> (4 cm40 mm <br />0.04 m <br />) +
pale tan +  and white +
2.4 cm24 mm <br />0.024 m <br /> (3.2 cm32 mm <br />0.032 m <br />) +
0.3cm;1.5cm +
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 +
spine-tipped +, serrate +  and entire +
fimbriate +, entire +  and toothed +
deciduous +  and persistent +
not mucilaginous +
dehiscent +, , +, rupturing +  and indehiscent +
abscission +
ridgelike +  and nipple--shaped +
Verh. Vereins Beförd. Gartenbaues Königl. Preuss. Staaten +
curving +  and straight +
constricted +
prominent +
broadly rounded +  and nearly keeled +
8 +  and 60 +
triangular +
arillate +  and strophiolate +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
dull +  and shiny +
subreniform;obovoid +
radial +  and cluster +
brown +, tan +, gray +, red +, pink +  and straw colored +
straight +  and curved +
deciduous +  and persistent +
5 (?) +  and 14 (?) +
annulate-ridged +
2 cm20 mm <br />0.02 m <br /> (5 cm50 mm <br />0.05 m <br />) +
decurrent +
unsegmented +
30 cm300 mm <br />0.3 m <br /> (80 cm800 mm <br />0.8 m <br />) +
grass green +, yellow-green +, gray-green +  and gray-blue +
4cm;40cm +
spheric +  and short cylindric +
succulent +
8cm;30cm +
olive +, pink +  and yellow +
tuberculate +
Homalocephala +
adventitious +
tuberlike +
epipetric +  and epiphytic +
Echinocactus +
Cactaceae subfam. Cactoideae +
flat +  and convex +
dull +  and glossy +
unbranched +  and branched +
epiphytic;epiphytic;epiphytic +
not deep-seated +
barrel-shaped +  and spheric +