Nearly 50 species of hedgehog cactus are native to the Southwest, including Texas, New Mexico, and Mexico. Some grow at fairly high elevations, where they survive freezing temperatures. All have cylindrical, ribbed stems in clumps; showy flowers in spring to early summer; and fleshy fruit that is edible in some species. Blooms come in red, yellow, purple, pink, or white and have many rows of petals; they typically close at night. Plant in masses for best effect. Excellent choices for dry-land gardens. Give them maximum sun and gritty, well-drained soil.
E. berlandieri. Zones LS, CS, TS; USDA 8-11. Stems 1 in. thick, 1 ft. long; forms a clump 2 ft. wide. Purplish pink, 3-in. flowers with darker throat. Good candidate for a hanging basket.
E. engelmannii. Zones MS, LS, CS, TS; USDA 7-11. Clumps 12 ft. tall, 3 ft. wide, with 3- to 4-in.-thick stems. Lavender to deep purplish red flowers are 23 in. wide. Inch-long red fruits are edible.
E. enneacanthus. STRAWBERRY CACTUS. Zones CS, TS; USDA 9-11. Stems 14 in. thick, 2 ft. long. Forms colonies 3 ft. wide. New stems start at or just above the ground and grow sideways, then upright. Goblet-shaped, purplish red, 2- to 3-in. flowers remain open at night. The inch-long, greenish to brownish purple fruit is edible and tastes like strawberries.
E. reichenbachii. CREAM LACE CACTUS. Zones US, MS, LS, CS, TS; USDA 6-11. Each stem is 2 in. thick, 6 in. tall. Plant may have a single stem or as many as a dozen. Large (4-in.) flowers vary from pink to magenta. White, lacy-looking spines.
E. triglochidiatus. CLARET CUP. Zones US, MS, LS, CS; USDA 6-9. Dense clump, up to 3 ft. wide, sometimes with hundreds of 2- to 3-in.-diameter stems to a foot tall. Flowers are 3 in. wide, orange to red; inch-long fruits (not edible) are pink to red.
E. viridiflorus. Zones US, MS, LS, CS, TS; USDA 6-11. Stems grow to 2 in. thick, 1 ft. long, forming a clump to 2 ft. wide. Slender, 1-in. flowers are yellowish green with a lemon scent; remain nearly closed day and night.