* Flowers yellow.
+ The originally central flowers pushed aside by the continuous
development of new tubercles: usually a single prominent
central spine.
37. Cactus missouriensis (Sweet) Kuntze, Rev. Gen. Pl. 259
(1891).
Cactus mamillaris Nutt. Gen. i. 295 (1818), not Linn. (1753).
Mamillaria missouriensis Sweet, Hort. Brit. 171 (1827).
Mamillaria simplex Torr. & Gray, Fl. N. Am. i. 553 (1840).
Mamillaria nuttallii Engelm. Pl. Fendl. 49 (1849).
Mamillaria notesteinii Britton, Bull. Torr. Bot. Club, xviii,
367 (1891).
Globose, 3.5 cm. in diameter, simple or nearly so: tubercles ovate-cylindrical, 12 to 14 mm. long, slightly grooved: radial spines 13 to 17, straight, whitish, setaceous, somewhat unequal, 8 to 10 mm. long; central spine more robust, straight and porrect, puberulent, 10 to 12 mm. long, often wanting: flowers about 2.5 cm. long, yellow or reddish: stigmas 2 to 5: fruit globose, scarlet, 6 to 8 mm. in diameter: seeds globose, black and pitted, 0.8 to 1.1 mm. in diameter. (Ill. Cact. Mex. Bound. t. 74., f. 6, seeds.) Type unknown.
High prairies of the Upper Missouri, from Montana to South Dakota and southward through western Nebraska to western Kansas and the eastern slopes of the mountains of Colorado. Fl. May.
Specimens examined: Montana (Notestein of 1893): National Park (Tweedy 423): South Dakota, (collector unknown, in 1847, 1848, 1853): Nebraska (Hayden of 1855).
38. Cactus missouriensis similis (Engelm.).
Mamillaria similis Engelm. Pl. Lindh. 246 (1845).
Mamillaria nuttallii caespitosa Engelm. Syn. Cact. 265 (1856).
Mamillaria missouriensis caespitosa Watson, Bibl. Index,
403 (1878).
Cespitose, with 12 to 15 puberulent radial spines, the central very often wanting, larger flowers (2.5 to 5 cm. long), fruit and seeds (1.6 to 2.2 mm. in diameter), and 5 stigmas. (Ill. Cact. Mex. Bound. t. 74. f 7, seeds) Type, Lindheimer, of 1845 (?) in Herb. Mo. Bot. Gard.