33 CACTACEOUS SLANTS. 



were associated with it — viz., M. prolifera and M. discolor, which at that 

 time, 1819, were all that were known. Since then, however, the number 

 of described species has been increased to 300, which abound in Mexico, 

 the head quarters of the genus, some being also found in the West Indies, 

 Brazil, and Bolivia, their habitats and the elevation at which they are 

 found varying considerably. In characters of flowers and fruit the 

 Mamillarias resemble several other genera, but the chief distinguishing 

 mark is found in the mamillae, papillse, or tubercles from which the plants 

 derive their name. The stem is cylindrical, globular, or conical, seldom 

 exceeding 10 or 12 inches high under cultivation, and more freqnently 

 only 3 to 6 inches high and 1 to 3 inches in diameter. From this axis 

 arise the teat-like projections termed the mamillse, but for which the word 

 tubercle is here adopted. These vary in size from minute elevations 

 scarcely a sixteenth of an inch high to some 1 inch high and as much in 

 diameter ; in form they also vary, from cylindrical, spindle-shape, 

 conical, or ovoid to angular and irregularly pyramidal. They are ar- 

 ranged spirally round the stem with great regularity, and each bears at 

 its apex a cluster of spines, often in two series, the outer white, very fine 

 and hair-like, from six to twenty, very closely set, and radiating laterally 

 in a star-like manner, much resembling the pappus crowning the fruits 

 of some plants in the Composite family ; the inner series is usually com- 

 posed of a few stifE spines, sometimes hooked at the points, and usually 

 coloured differently from the others, being yellow, brown, red, or purplish. 



The variations in these organs or appendages furnish the chief charac- 

 ters for distinguishing the species, and upon them some authors have 

 constructed an elaborate system of classification in groups and sec- 

 tions. In Hooker and Bentham's " Genera Plantarum," however, Engel- 

 rcanu's three subgenera Bumamillaria, Coryphanta, and Anhaloninm are 

 adopted for the main divisions. The first includes the majority of the 

 species, which are characterised by the tubercles not being furrowed, and 

 by the flowers being produced from the axils of the previous year's 

 tubercles — that is, from the side of the stem. The second has furrowed 

 tubercles, and the flowers produced from the apex of the stem or from 

 the axils of the tubercle of that season's growth. The third was con- 

 stituted a genus by Lemaire, but is regarded as inseparable from the 

 Mamillarias, though in general appearance they are quite different, the 

 ubercles in Anhalonium being spreading, thick, and leaf-like, sometrhat 

 after the style of the Gasterias. 



Culture. — Many of the Mamillarias are found in limestone districts, 

 and though inhabiting varying climates and elevations, they may be 

 all grown in an intermediate temperature, such as a greenhouse, where 

 they can be protected from frosts during the winter, but a higher tempe- 



