This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Stems solitary or clustered, globose or ovoid, tubercled. Tubercles conic or cylindric, grooved, at least in many species, woolly and with clusters of spines at the apex. Leaves none. Flowers borne from areolae at the bases of the tubercles. Calyx-tube campanulate or funnel-form, produced beyond the ovary, which is often hidden between the tubercles. Petals in several rows. Ovary smooth, ovoid; style filiform. Berry ovoid or club-shaped, emersed, sometimes crowned by the withering corolla. [Greek, summit-flowering, the flowers being produced near the top.]
Perhaps 100 species, natives of warm and tropical America. Besides the following, many others occur in the southwestern States. The generic name Cactus used for these plants in our first edition belongs to the Turk's-head Cacti of tropical America. Type species: Mamillaria sulcata Engelm.
Cactus mamillaris Nutt. Gen. 1: 295. 1818. Not L. 1753.
M. Nuttallii Engelm. Mem. Am. Acad. 4: 49. 1849.
Cactus missouriensis Kuntze, Rev. Gen. Pl. 259. 1891.
Stems mostly single, globose, 1'-2' high. Tubercles 6"-8" long, arranged in about 8 spiral rows, slightly grooved; spines gray, 10-20 together, the stouter central one 5"-6" long, or wanting; flowers yellow, or reddish, about 1' long and about the same breadth when expanded; petals 2"-3" wide, acute, abruptly mucronate; stigmas 2-5, very short, erect; berry globose, scarlet, 3"-4" in diameter, ripening the following spring; seeds black, globose, pitted, about i" in diameter.
Plains and dry soil. North Dakota to Kansas and Texas, west to Colorado. Pelots. May.
Cactus viviparus Nutt. Fraser's Cat. 1813.
Stems single or tufted, 1-5' high, 1 1/2-2' in diameter. Tubercles terete or nearly so, slightly grooved, bearing 3-8 slender reddish-brown spines 6"-10" long, surrounded by 12-25 somewhat shorter, whitish or greenish ones in a single row; flowers purple, nearly 2' long; petals lanceolate, narrow; sepals fringed; berry ovoid, 6"-9' long, green; seeds light brown, obovoid, curved, pitted, about \" long.
Plains and rocky soil, Minnesota to Manitoba, Alberta, Kansas, and Colorado.