Origin and Habitat: Known only from Sierra de la Paila, north of Parras de la Fuente, Cent.-S and SE Coahuila ( Sierra Madre Oriental), Mexico.
Altitude range. 1700-2000 metres above sea level.
Habitat and ecology: Chihuahuan Desert and pinon pine forest. Echinocereus longisetus subs. delaetiiSN|6788]]SN|6788]] grows on limestone slopes together with Mammillaria chionocephalaSN|15848]]SN|15848]], Coryphantha lauiSN|10061]]SN|10061]], Gymnocactus beguiniiSN|1913]]SN|1913]], and Escobaria zilzianaSN|10435]]SN|10435]].

• Echinocereus longisetus subs. delaetii (Gürke) N.P.Taylor
• Cephalocereus delaetii Gürke
• Echinocereus delaetii (Gürke) Gürke
• Echinocereus longisetus var. delaetii (Gürke) N.P.Taylor

• Echinocereus longisetus (Engelm.) Rümpler
• Cereus longisetus Engelm.
• Echinocereus barcena Rebut ex A.Berger

• Echinocereus longisetus subs. delaetii (Gürke) N.P.Taylor
• Cephalocereus delaetii Gürke
• Echinocereus delaetii (Gürke) Gürke
• Echinocereus longisetus var. delaetii (Gürke) N.P.Taylor

• Echinocereus longisetus subs. freudenbergeri (G.Frank) W.Blum in W.Blum et al.
• Echinocereus delaetii var. freudenbergeri (G.Frank) N.P.Taylor
• Echinocereus freudenbergeri G.Frank

• Echinocereus longisetus var. rayonesensis (N.P.Taylor)
• Echinocereus rayonesensis N.P.Taylor

Description: Echinocereus delaetiiSN|8281]]SN|6789]] (now regarded as Echinocereus longisetus subs. delaetiiSN|6789]]SN|6788]]) is a low, densely cespitose cactus with stems covered with long weak bristles or hairs. Over time, it can form -wide clumps up to 35 cm tall and 90 cm in diameter comprised of as many as 50 stems, but in cultivation it is typically smaller. Echinocereus delaetiiSN|6789]]SN|6789]] is one of the most remarkable species in the genus, that very much resembles a small plant of Cephalocereus senilisSN|6893]]SN|6893]], and owing to this resemblance it was first described as a Cephalocereus. Its flowers, however, are so different from those of that genus that as soon as they were seen the plant was at once transferred to Echinocereus. Unfortunately, although Echinocereus delaetiiSN|6788]]SN|6789]] will always appeal to collectors because of its long white hair, it seems to be rather reluctant to flower. The flowers are pink, the ovary is also hidden by clusters of long white bristles.
Derivation of specific name: This member of the Cactaceae family was named in honor of Frantz de Laet, a Belgian cactus dealer, who had imported many plants from Mexico through Dr. C. A. Purpus and other collectors.
Stems: Low, densely clustering, 10-20(-35) cm high, 3-8 cm in diameter, completely hidden by the long, white, curled hairs.
Ribs: 17-24 indistinct (less than 17 in Echinocereus longisetusSN|6789]]SN|8281]]).
Areoles: Closely set
Spines: 15 or more, reduced to white (or brownish white) hairs, and variously wavy or curled 8 to 10 cm long and a few stiff reddish bristles.
Flowers: Pink to pale purple, slightly drooping with yellow centres, 5.7-10 cm long, 5.8-12.5 cm in diameter, appearing near the top of the plant. Perianth-segments pink, oblanceolate, acute to 55 mm long and 15 mm wide. Stigma-lobes about 12, green. Ovary covered with clusters of long, white, bristly spines.
Flowering season. Late spring through early summer. In cultivation, some collectors report that it is difficult to coax into flower, but in mild climates it flowers easily when grown in the ground.

Bibliography: Major references and further lectures
1) Nathaniel Lord Britton, Joseph Nelson Rose “Cactaceae: Descriptions and Illustrations of Plants of the Cactus Family” Volume 3, 1922
2) James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11 August 2011
3) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
4) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
5) Echinocereus delaetii: The National Cactus and Succulent Journal: The Official Journal of the National Cactus & Succulent Society, National Cactus and Succulent Society, 1980
6) Echinocereus delaetii: Bradleya: Yearbook of the British Cactus and Succulent Society, The Society, 1988
7) Echinocereus delaetii: Cactaceas y Suculentas Mexicanas 31(4): front cover, fig. 36(1986)
8) Graham Charles “Cacti and Succulents: An illustrated guide to the plants and their cultivation” Crowood, 30 April 2014
9) Clive Innes “Complete Handbook of Cacti and Succulents” Van Nostrand Reinhold Company, 01 December 1981
10) Scott Calhoun “The Gardener' s Guide to - Cactus - The 100 Best Paddles, Barrels, Columns, and Globes” Timber Press, Inc. Portland-London 2012
11) Earle, Wh, “Powder puff, Echinocereus delaetii, Cactaceae, cactus family.” Saguaroland bulletin: 26 (9) 100.1972

Cultivation and Propagation: Echinocereus delaetiiSN|6789]]SN|6789]] is a very individual looking species with long white hairs reminiscent of an espostoa. It has the fame to be one of the more difficult to grow. It needs a very bright locality to grow well, soon making a clump of thick stems which then might produce its lovely pink flowers but only sparingly.
Water requirements: Less than average water at all times suits this choice plant. It rots easily and is very sensitive to overwatering (rot prone), so perfect soil drainage is a must.
Exposure. In the summer they need an airy location in bright sun; well watered when it's hot. To achieve the best spine density give these plants lots of sun.
Hardiness: In the winter light, cool, and absolutely dry conditions. It is cold resistant above approx -9 C or less for short periods of time. Hardiness Zone 8. In mild climate they grow well when planted freely outside in well-drained soil.
Pest and diseases: It is also rather susceptible to red spider mite, which can ravage the plant while concealed by the hairs.
Propagation: Seeds, Cuttings. It is best raised from seed.