Dahlia Apple Cactus

Echinocereus poselgeri, with tuberous roots and erect, slender, elongate stems, superficially resembles some Peniocereus species. The polyphyletic genus Wilcoxia Britton & Rose formerly included this species along with species of Peniocereus. The flowers, fruits, and seeds of E. poselgeri are typical for Echinocereus, quite similar to those of E. reichenbachii.

Plants straggling, very tall and slender, sparingly branched at any level. Stems initially erect, later sprawling or clambering, long cylindric, 12-60(-130) × 0.6-1(-2) cm; ribs 8-10, crests low, uninterrupted or shallowly undulate; areoles 1-2-5 mm apart. Spines (9-)11-13(-17) per areole, stiff and straight, usually tan, brown, or black, sometimes yellow, pale pink, ashy white, or gray, sometimes black central spines contrasting with white radial spines; radial spines 8-16 per areole, 2-5 mm; central spines 1(-3) per areole, closely appressed (except at the stem tip), terete, 4-9 mm. Flowers 3.5-6 × 3.5-7 cm; flower tube 15-20 × 7-18 mm; flower tube hairs 3-5(-10) mm; inner tepals rose-pink with darker pink to magenta midstripes, proximally darker, 25-35 × 4-12 mm, tips relatively thin and delicate; anthers yellow; nectar chamber 1-4 mm. Fruits dark green to brownish, 2-3 cm, pulp white. 2n = 22.

Tex.; Mexico (Coahuila, Nuevo León, Tamaulipas).

Flowering Mar-Apr; fruiting 2.

-3 months after flowering. Tamaulipan thorn scrub, alluvial soils; 0-200[-1100]m.

Echinocereus tuberosus (Poselger) Rümpler; Wilcoxia poselgeri (Lemaire) Britton & Rose