Echinocereus engelmannii
Echinocereus davisii
calico cactus, Engelmann's hedgehog cactus, strawberry hedgehog cactus
Davis' hedgehog cactus
mostly erect, cylindric or somewhat tapering distally, (5–)14–45(–70) × 3–9 cm;
ribs 10–13, crests slightly undulate;
areoles 6–10(–15) mm apart.
erect, spheric, (1–)2–3 × 1–2(–2.5) cm;
ribs 6–9, crests poorly defined, undulate;
areoles of largest plants 6–7(–10) mm apart.
(8–)15–20 per areole, usually straight (curved and twisted in desert mountains and peninsular ranges of California), individual spines with broad zones of different colors: whitish or grayish, dull golden-yellow, or reddish brown to nearly black;
radial spines 6–14 per areole, 8–20(–50) mm;
central spines (2–)4–6(–9) per areole, divergent-porrect, 12–70 mm, abaxial central spine often fading whitish, flat to sharply angled (terete or nearly so in north-central Arizona).
8–14(–15) per areole, in relatively old plants curving irregularly in random directions, gray or white, some or all tipped black, dark reddish brown, or dull reddish purple;
radial spines 8–14 per areole, ± pectinately arranged, (5–)10–15(–19) mm;
central spines 0(–1) per areole, terete, 10–12 mm, closely resembling largest radial spines.
6–9 × 5–9 cm;
flower tube 13–30 × 10–30 mm;
flower tube hairs 1 mm;
inner tepals bright rose-pink to magenta, often varying from paler to darker in same population, proximally darker, 37–75 × (8–)14–25 mm, tips relatively thin, delicate;
anthers yellow;
nectar chamber 4–6 mm.
1.5–2 × 1.5–2(–2.7) cm;
flower tube 5–8 × 5–10 mm;
flower tube hairs very short, inconspicuous;
inner tepals bright yellow-green, often with maroon midstripes, 9–18 × 2.7–3.8 mm, tips relatively thin and delicate;
anthers yellow;
nectar chamber 1 mm.
red or orangish, 25–45 mm, pulp whitish becoming infused with pink or red from the skin.
purplish brown or remaining green when ripe, 5.5–9(–11) mm, pulp white.
= 44.
= 22.
Echinocereus engelmannii
Echinocereus davisii
The characteristics distinguishing Echinocereus engelmannii from E. fasciculatus to the east are poorly documented, and W. Blum et al. (1998) combined the two as separate subspecies of E. engelmannii. Historically, E. engelmannii has been characterized as having the abaxial central spine in each areole particularly long, pale, and strongly compressed dorsiventrally (sharply angled, hence daggerlike), contrasting with the other spines. In practice that trait is not always diagnostic. Plants called Echinocereus engelmannii var. acicularis L. D. Benson are essentially morphologically and geographically intermediate between those referred to E. fasciculatus and E. engelmannii var. chrysocentrus.
The history of confusion with Echinocereus nicholii has resulted in misidentification of yellow-spined individuals of E. engelmannii.
Spine color polymorphism, common within Echinocereus engelmannii, provided the original basis for varieties chrysocentrus and purpureus. The well-marked, identifiable extremes often occur in populations that include individuals easily assigned to other named varieties, or not assignable to any. L. D. Benson (1969, 1982) and subsequent authors (e.g., N. P. Taylor 1985; W. Blum et al. 1998) have attempted to recognize infraspecific taxa within E. engelmannii. However, one of those is clearly a distinct species (E. nicholii), while the remainder are either too poorly defined or too poorly known to treat fully here. At higher elevations beyond the western edge of the desert, E. engelmannii var. munzii (Parish) P. Pierce & Fosberg has been distinguished by its curving, twisting, gray spines, somewhat resembling spines of westernmost plants of E. triglochidiatus var. mojavensis. Plants of the western Sonoran Desert margin in the Mexican boundary region in California are the typical E. engelmannii var. engelmannii. Similar plants from the opposite, eastern, side of the Sonoran Desert, in Arizona, have been called E. engelmannii var. acicularis L. D. Benson. In the intervening Colorado River Valley is spinier E. engelmannii var. chrysocentrus (Engelmann & J. M. Bigelow) Rümpler. In E. engelmannii var. acicularis at the lowest altitudes, central spines are usually four, in which cases taxonomic segregation from E. engelmannii var. chrysocentrus seems arbitrary. At higher altitudes, plants of E. engelmannii var. acicularis with only one or two central spines per areole are frequent, and the abaxial central spine may be terete instead of angular and daggerlike as in E. engelmannii var. chrysocentrus. The most formidably spiny extremes of the species were segregated as E. engelmannii vars. howei and armatus; however, other individuals in the original populations (type localities) are readily assigned to E. engelmannii var. chrysocentrus. W. Blum et al. (1998) placed all of the above varieties under E. engelmannii subsp. engelmannii.
Plants smaller in all parts and with fewer central spines from north-central Arizona are Echinocereus engelmannii subsp. decumbens (Clover & Jotter) W. Blum & Mich. Lange. L. D. Benson (1969) referred those to var. variegatus (Engelmann & J. M. Bigelow) Rümpler, but the type locality of var. variegatus is in a different region. The status of E. engelmannii var. purpureus L. D. Benson remains uncertain; its similarity to unidentified diploid material found in northern Arizona suggests that it could be a separate species, but more variable than its original diagnosis allowed.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The relatively heavy, brown-and-white, often slightly contorted radial spines of Echinocereus davisii help to distinguish these tiny plants from seedlings of their larger congeners; remains of flowers and fruits, such as scattered flower tube spine-clusters, provide proof of sexual maturity. Echinocereus davisii is easily distinguished from E. viridiflorus; it is parapatric with E. viridiflorus without evidence of introgression. Echinocereus davisii is less compatible with E. viridiflorus than any varieties of E. viridiflorus are with one another (E. E. Leuck 1980).
Echinocereus davisii is in the Center for Plant Conservation’s National Collection of Endangered Plants.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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