Echinocereus russanthus var. neocapillus
This species has an upright solitary stem with dense golden spines and greenish flowers,
 it is remarkable for its softly hairlike, not sharply spiny, seedlings.
 

Description: This cactus is rather small in size and usually solitary but can branch and form small clusters about 15 cm  wide.
Stem: Upright 6-8(-15) cm tall and forms a clump about 5" wide. Each head is about 4cm wide only.
Spines: Mature specimens have dense golden spines obscuring the stems, radiating in all directions, while the juvenile growth is marked by soft white hairlike spines
Flowers: it produces plenty of yellow-green flowers 1,5-2,5cm in diameter and they are fragrant. Well, if you think the smell of lemon is fragrant that is.
Blooming season: In mid to late spring,

Origin: This cactus was originated from New Mexico near Albuquerque.
 

Synonyms:

• Echinocereus chloranthus var. neocapillus Weniger
  D. Weniger
  Published in: Cact. Succ. J. (Los Angeles) 41: 39, fig. 4. 1969.
• Echinocereus chloranthus subsp. Neocapillus
• Echinocereus viridiflorus neocapillus,

Cultivation: In culture E. russanthus is without problems and regularly shows its small  purplish flowers if we provide an adequate winter rest period. Very hardy for a cactus.  But remember, the soil has to by dry.
This plant tends to lose it's roots and shrink in the wintertime, but in summertime needs more water. It is sensitive to overwatering (rot prone) needs good drainage, Keep drier and cool in winter. Need full sun; Very cold resistant hardy to -10° C or less for short periods of time.

Propagation: Seeds or cutting (if available)

Photo of conspecific taxa, varieties, forms and cultivars of plants belonging to the Echinocereus viridiflorus complex.
E. russanthus is part of the E. viridiflorus compless that comprises a large number of infraspecific taxa, differing in various combinations of flower color, spine color, number and thickness of central spines, and other characters, including floral scent. Wherever such taxa are sympatric they intergrade; all are freely interfertile in the greenhouse. Among them:

• E. viridiflorus var. viridiflorus: (Typical form) With small stems and relatively pure yellow flowers, extends from central New Mexico and the Texas Panhandle to South Dakota. (E. viridiflorus var. robustior) is a more robust form but not sufficiently differentiated and considered merely  a local variant of  E. viridiflorus v. viridiflorus.
• E. viridiflorus var. chloranthus (E. chloranthus) with the most numerous central spines (five or more per areole), giving the plants a bristly appearance, are often considered a separate species.
• E. viridiflorus var. russanthus (E. russanthus) : Plants with a bristly appearance usually with reddish or russet flowers. Yellow-spined plants may occur at high altitudes.
• E. viridiflorus var. cylindricus (E. chloranthus var. Cylindricus) : The common morphotype at middle altitudes in Texas and southeastern New Mexico has 0-2(-3) central spines.
• E. viridiflorus var. correllii  (E. chloranthus var. Cylindricus "corellii") A poorly defined, yellow-spined population near Marathon, Texas.
• E. viridiflorus var. neocapillus (E. chloranthus var. neocapillus): Remarkable for its softly hairy, not sharply spiny, seedlings.
• E. chloranthus subsp. rhyolithensis Bristly red-spined plants from New Mexico.

Echinocereus viridiflorus in the broad sense may prove paraphyletic with respect to E. davisii, but they are phenologically isolated, with E. davisii flowering earlier and thus appearing reproductively isolated in the wild.