Mammillaria radiosa     Engelmann in A. Gray, Boston Journal of Natural History, 6(2): 196-197. 1850.

Gray, A.: Plantae Lindheimerianea, Part II. An Account of a Collection of Plants made by F. Lindheimer in the Western part of Texas, in the Years 1845-6, and 1847-8, with Critical Remarks, Descriptions of new Species, &c., Boston Journal of Natural History, 6(2): 141-240. 1850.


Mammillaria radiosa (sp. nov.)

Simplex s. parce prolifera, ovata seu cylindrica; tuberculis teretibus supra plus minus sulcatis apice ex tomento albo aculeatis; aculeis rectis numerosis valde insequalibus, plurimis (20-30) radiantibus tenuioribus albidis, centralibus 4-5 robustioribus fuscis s. rarius flavis, 3-4 sursum directis, singulo deflexo; axillis nudis, sulco subtomentoso; floribus (violaceis) ex axillis tuberculorum hornotinorum ortis sparsis (nee centralibus); sepalis petalisque lineari-lanceolatis acuminatis aristatis; sepalis (40-50) arachnoideo-fimbriatis, exterioribus brevioribus adpressis, interioribus longioribus recurvatis; petalis (30-40) integris s. basi subciliatis patentibus; staminibus (violaceis) numerossimis oequalibus; stylo longe exserto; stigmatibus 7-9 (violaceis) erectis obtusis; bacca oblonga viridi floris rudimento coronata; seminibus fulvis ovatis scrobiculatopunctatis. — Sterile, sandy soil on the Pierdenales: flowers (in St. Louis) about the middle of June. The flowers open for three days, in direct sunshine only, and later than most other Cactaceae, viz., from 12 or 1 till 3 or 4 o'clock. Stems 2-4 inches high, about 2 inches in diameter, dark green; tubercles in 13 oblique rows; (1) radiant spines 3-4; central spines from 4-6 lines long: flowers 1 1/2-2 1/4 inches long, and about the same diameter when fully open, of a lighter violet color or of a splendid dark purple: stigmas deep velvety purple. — Very near M. vivipara, Haw., which has been found from the Upper Missouri to Santa Fe: this, however, is distinguished by its low, mostly csespitose growth, by the smaller number of radiant spines (14-18), the absence of the deflexed central spine, the smaller central flowers, the apiculate stigmata, and smaller seeds: it also flowers earlier (in St. Louis about the middle of May), but, like M. radiosa, opens the flowers only after 12 o'clock. In M. vivipara the youngest tubercles produce in their axils the flowers which appear central, and remain so till after fructification, whereupon new tubercles are developed in the centre, and the young fruit is pushed aside and becomes more and more lateral. In M. radiosa the flower buds are also formed in the axils of the first young tubercles of the season, but are immediately pushed aside by a continuous growth of more tubercules; the buds as well as the flowers and fruits are therefore lateral. M. vivipara has not yet been found in Texas, though it may be expected in the mountainous regions bordering New Mexico.

(1) It will hardly be necessary to mention that there are several different sets of rows of tubercles observable, but one set is usually more distinct than the others; they depend on the size of the plant, and the immber, size, and closeness of the tubercles. It is well known that in different specimens of the same species theyturn to either side, right or left.




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Last modified December 29, 2010

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