rs at the base, and crowned with
tufts of from four to seven spines, usually all radial, sometimes one
central. The flowers, which usually appear in May, are arranged in a
zone on the top of the old stems; sepals greenish-yellow, petals bright
red. Fruit 1 in. long, pear-shaped, scarlet. Native of South Mexico, at
high elevations. It may be grown outside in summer, and wintered in a
heated greenhouse or frame. This is a singular-looking plant, the
tubercles having an appearance suggestive of carving. It is a slow
grower, and requires careful attention in winter, when sometimes the
roots all perish and the base of the stem rots.

[Illustration: FIG. 71. MAMILLARIA SUB-POLYHEDRA.]

M. sulcolanata (woolly-grooved); Fig. 72.--Stem simple when young,
proliferous at the sides when old, the young plants developing from the
apices of the tubercles, and not in the axils, as is usual. The
tubercles are nut-shaped, large, the bases surrounded by white wool, the
points bearing eight to ten rigid, brown spines, all radiating from a
little pad of wool. Flowers large, nearly 2 in. across, bright yellow,
poppy-scented, the spread of the petals suggesting Paris Daisies; they
are freely developed on the apex of the stem in June, and on till
August. Fruit egg-shaped, glaucous-green. Native country, South Mexico;
introduced 1836. This charming little plant should be grown in a frame
exposed to full sunshine all summer, and removed to a shelf in a warm
greenhouse in winter. With such treatment it grows and flowers freely.
Grafted on to a Cereus or Opuntia it is healthier than when on its own
roots.

[Illustration: FIG. 72. MAMILLARIA SULCOLANATA.]

M. tetracantha (four-spined); Bot. Mag. 4060.--Stem the size and shape
of an ostrich's egg, thickly studded with small, conical tubercles,
woolly at the base, the apices bearing each four spreading spines, 3/4 in.
long, rather stout, straight, brown when young, becoming almost white
with age. Flowers numerous, small, arranged as in M. sanguinea, to which
and M. cirrhifera this species is closely related. They are bright rose
in colour, with orange-yellow anthers, and are developed in July. Native
of Mexico. Requires the same treatment as M. cirrhifera.

M. tuberculosa (tubercled).--This is a very pretty and distinct plant,
of recent introduction, and easily cultivated. It has a central stem,
6 in. high by 2 in. in diameter, conical in shape, and surrounded at the
base by globose branches or