m globose, about 4 in. in
diameter; tubercles smooth, egg-shaped, their bases embedded in white
wool, their tips crowned with stellate tufts of short, reddish spines.
Flowers numerous, and borne from almost all parts of the stem, less than
1 in. wide, and composed of a single whorl of narrow, reflexed,
rose-purple petals, surrounding a large, disk-like cluster of yellow
stamens. The flowers are so short that they are half hidden by the
tubercles. It is a native of Mexico, where it grows on rocks, in warm,
sheltered places. Under cultivation it thrives when grown on a dry shelf
in a warm house, and kept moist in summer, but perfectly dry in winter.

M. dolichocentra (long-spurred); Fig. 58.--Apparently this is a
variable species; at all events, plants of widely different habit are
found under this name, one of them represented in the Figure here,
another in the Garden, Vol. XVII., whilst others are figured or
described in other books. What is known at Kew as the true plant is that
here figured. This has a stout stem, about 8 in. high and 3 in. wide, and
covered with smooth cone-shaped mammae, with woolly bases and stellate
tufts of spines on their tips. The flowers are produced about 1 in. from
the top of the stem, and are less than 1 in. wide; they are, however,
often very numerous, sometimes a closely-set ring of them surrounding
the stem, like a daisy chain, their colour being pale purple. Below the
flowers there is often a whorl of club-shaped fruits, 3/4 in. long, and
rose-coloured. These contain numerous little black seeds, which, when
ripe, may be sown in pots of very sandy loam. The plant is a native of
Mexico, and flowers in summer. It thrives in a tropical temperature, and
enjoys a daily syringing overhead on bright days in summer, but in
winter requires little or no water.

[Illustration: FIG. 58. MAMILLARIA DOLICHOCENTRA.]

M. echinata (hedgehog-like).--A charming little plant, with very small
stems, clustered together in a cushion-like tuft, each stem less than
1 in. wide; but a well-grown specimen is composed of dozens of these,
packed almost one on top of the other. The tubercles are hidden by the
star-like spine clusters which cap them, and look like a swarm of
insects. Flowers very small, rose-coloured, and lasting only about a
day. These are succeeded by numerous currant-like red berries, so
numerous, in fact, that the plants look as if thickly studded all over
with coral beads. The central stem is so