M. multiceps (many-branched).—­Stem short, with numerous branches, which again push forth other branches, so that a dense tuft of dumpy, globose stems is formed.  The mammae are small, and arranged closely together, and they each bear a tuft of whitish wool, with a radiating cluster of spines, which are soft, almost hair-like in texture, the inner ones being stiffer, and coloured dull yellow.  The flowers are small, and almost hidden by the spines and tubercles; they are pale yellow, with a line of red down the middle of each petal.  Native country, Mexico.  This plant should be grown on a shelf in a cool greenhouse—­anything like a stove temperature being fatal to it.  As a flowering plant it is of no value, but the compact tuft formed by its numerous stems, with their attractive spines, renders it worthy of cultivation.

M. Neumanniana (Neumann’s).—­This is a member of the group with angular tubercles and comparatively small flowers.  It has a stem about 6 in. high, cylindrical, the tubercles arranged spirally, their bases compressed, four or five-angled, and with a tuft of white wool in their axils.  The areoles or tufts on the tops of the mammae are large, and the spines are about seven in number, 1/2 in. long, and of a tawny-yellow colour.  The flowers are produced near the top of the stem; they are about 1/2 in. long, and rose-red in colour.  Native country, Mexico.  It requires the same treatment as M. cirrhifera.

M. Ottonis (Ottoni’s); Fig. 66.—­A very distinct and pretty plant is cultivated under the name at Kew; but there are, apparently, two different species under the same name—­the one being spiny and large in the stem; the other, which is here shown, having a small, compressed stem, 3 in. across, numerous compressed tubercles, and short, hair-like spines.  The flowers, which are large for the size of the plant, are white, and are developed in May and June.  Native country, Mexico; introduced in 1834.  It requires similar treatment to M. micromeris.

[Illustration:  Fig. 66.  Mamillaria ottonis.]

M. pectinata (comb-like); Fig. 67.—­Stems globose, from 2 in. to 3 in. in diameter; the rootstock woody; the tubercles arranged in about thirteen spiral rows, swollen at the base, and bearing each a star-like tuft of about twenty-four stiff, brown, radial spines, without a central one; the length varies from 1/2 in. to 1 in., and they are comb-like in their regular arrangement.  When not in flower, this species bears a close resemblance to small plants of Cereus pectinatus.  Flowers terminal, solitary, large, their width quite 3 in. when fully expanded; sepals reddish-green; petals rich sulphur-yellow; filaments reddish, very numerous; the flowers open at noon, and close after about two hours, even although the sun be shining full upon them.  Flowering season, June to August.  Native country, Mexico, on slopes of limestone hills.  Although long since known to botanists, this pretty species has only lately found its way into English gardens.  It is attractive even when not in flower.  It requires warm greenhouse treatment, with exposure to full sunshine; during late autumn it should have plenty of air to ripen the new growth made whilst flowering.  In winter it should have a dry position near the glass.