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 sometimes about 6 in. high, those surrounding it being shorter and shorter, till the outside ones rise only just above the soil.  A well-grown plant of this is strikingly pretty, even when not in fruit.  It is a native of Mexico, and requires the treatment of a warm house.  A few pieces of broken brick should be placed upon the surface of the soil about the base of the plant, as the stems like to press against, or grow upon, anything in the nature of rocky ground.

M. echinus (hedgehog-like); Fig. 59.—­A distinct and pretty little plant, the largest specimen having a stem about the size and shape of a small hen’s-egg, completely hidden under the densely interwoven radial spines, which crown the thirteen spiral rows of tubercles, and are almost white when mature.  The tubercles are 1/2 in. long, and, in addition to these white radiating spines, they also bear each a stout spike-like spine, growing from the centre of the others.  This spine gives the plant an appearance quite distinct from all other cultivated Mamillarias.  The flowers are produced two or three together, on the top of the stem, and they are nearly 2 in. long, cup-shaped, and coloured yellow; they usually appear about June.  As yet this species is rare in cultivated collections.  It comes from Mexico, where it is found growing on limestone hills, in hot and arid localities.  Under cultivation it requires a warm greenhouse temperature, exposure to bright sunshine all the year round, with a moderate supply of water in summer, and none at all during winter.  A few large pieces of broken brick or sandstone placed in the soil, just under the base of the stem, afford the roots conditions suitable to their healthy growth.

[Illustration:  Fig. 59.  Mamillaria echinus.]