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.
Description:
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.
© 2002-2010 Jan Mynar
Last modified December 29, 2010