Echinocereus poselgeri

Echinocereus poselgeri, also known as the dahlia cactus, is a species of Echinocereus. It is native to Coahuila and southern Texas.

Description
Echinocereus poselgeri typically grows with several spreading shoots, forming a tuberous, dahlia-like rhizome. The dark blue-green shoots are slender, cylindrical, and taper to a point, measuring 60 to 120 cm long and 1 to 2 cm in diameter. They have eight to ten low, inconspicuous ribs that are not tuberculated. A single, slightly flattened, dark central spine points toward the shoot tip and is up to 9 mm long. The eight to 16 whitish or grayish marginal spines, which have darker tips, are 2 to 4.5 mm long.

The funnel-shaped flowers are slightly pinkish-magenta, appearing near the tips of the shoots. They can be up to 6 cm long and 7 cm in diameter. The dark green to brown fruits are egg-shaped and covered with persistent wool and thorns.

Distribution
Echinocereus poselgeri is growing in scrub valleys and hills of southern Texas, USA, and the Mexican states of Coahuila, Nuevo León, Tamaulipas, and San Luis Potosí, typically found at low elevations in sandy soil at elevations up to 1150 meters.

Taxonomy
Charles Lemaire first described the species in 1868. The specific epithet poselgeri honors Heinrich Poselger, a German doctor, chemist, and botanist who collected succulent plants in North America from 1849 to 1851.