5 SEEDS

This cactus has stems about 1/2-1 inch wide with 6-9 edges. Its flowers are white, up to 30 centimetres in diameter with a scent redolent of vanilla. The flowers open after sundown, closing and wasting after a few hours. By 9 am the next day they are gone. They usually bloom one night a year in June or July. In any given area, they all bloom at the same time. They look dead during the rest of the year. They have a large tuber that tastes a bit like a potato. They tend to be ubiquitous throughout the higher Sonoran Desert area around Tucson. See "A Natural History of the Sonoran Desert" published by the Arizona-Sonora Desert Museum, pg 197.

Tohono Chul in Tucson, Arizona has the largest private collection of Sonoran Desert native Night-blooming Cereus - Peniocereus greggii. Each summer this botanical garden/museum hosts "Bloom Night," the one night each summer it is predicted the greatest number of cereus flowers will be in bloom, opening from 6pm until midnight to allow guests to stroll the grounds and view the flowers.

Shrubs, erect to sprawling, usually inconspicuous. Roots turnip-shaped, usually 15-30 × 5-12 cm (much larger ones known). Stems gray-green to gray, simple or with 2-5 branches, 40-120(-300) cm, distally 8-20 mm diam., at midlength ca. 10 mm diam., often narrowed toward base; wood hollow, solid-surfaced cylinders, 4-7 mm diam.; ribs 4-6, prominent; areoles (3.5-)12(-15) mm apart along ribs, circular to elliptic, 2-5 × 2 mm. Spines (9-)11-15(-17) per areole, usually in 3 vertical rows; abaxial 3-5 spines appressed, yellowish white throughout or only at tips, to 3 mm, puberulent when young; adaxial spines black, subulate, to 1 mm. Flowers: nocturnal (remaining open next day), 15-25 cm; scales of flower tubes green, tipped red or brown; outer tepals greenish white with brown to reddish midstripes; inner tepals white or lightly tinged cream or pink (or rarely all rose-pink), lanceolate-attenuate, apiculate, 4-7 cm, attenuate to mucronate; stamens 2.5 cm; anthers cream-yellow, 2 mm; style white, 10-14 cm; stigma lobes 9-11, white. Fruits bright red, darkening in age, ellipsoid, 60-90 × 40-50 mm. Seeds 3-4 × 2-2.5 mm. 2n = 22.