9.
Echinocereus engelmannii
(Parry ex Engelmann) Lemaire, Cactées. 56. 1868.
Engelmann's hedgehog cactus, strawberry hedgehog cactus
Cereus engelmannii
Parry ex Engelmann, Amer. J. Sci. Arts, ser. 2, 14: 338. 1852 (as engelmanni);
Echinocereus engelmannii
var.
armatus
L. D. Benson;
E. engelmannii
var.
chrysocentrus
(Engelmann & Bigelow) Rümpler;
E. engelmannii
var.
howei
L. D. Benson
Plants
3-60-branched, ultimately forming somewhat open clumps.
Stems
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.
Spines
(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).
Flowers
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.
Fruits
red or orangish, 25-45 mm, pulp whitish be-coming infused with pink or red from the skin.
2
n
= 44.
Flowering Mar-Apr; fruiting May-Jul. Sonoran and Mojave deserts, chaparral, pinyon-juniper woodlands; 200-2400 m; Ariz., Calif., Nev., Utah; Mexico (Baja California, Sonora).
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.
