n diameter. Tubercles dark green,
conical, 1/3 in. long, 1/2 in. broad at base, naked at the point, but with
four to six spines springing from the areole a little below the point;
spines ash-coloured, stiff, black-tipped. Flowers in a ring about the
top of the stem, length 1 in., the tube enveloped in long, black, twisted
hairs; sepals brown-purple; petals narrow, sharp-pointed, purple-rose
coloured; stamens white and yellow; stigma rose-coloured. Flowers in
June and July. Native of Mexico. A large, handsome-stemmed kind, easily
kept in health, and flowering freely if grown on a shelf in a cool
greenhouse in winter, and placed in a warm, sunny position out of doors
in summer. It produces seeds freely, and pretty plants, 3 in. or more in
diameter, may be obtained in two years from seeds. By grafting it, when
young, on the stem of a Cereus or cylindrical Opuntia, a healthy,
drumstick-like plant is easily obtained.

CHAPTER XII.

THE GENUS LEUCHTENBERGIA.

(Named in honour of Prince Leuchtenberg.)

Among the many instances of plant mimicry that occur in the Cactus
order, the most remarkable is the plant here figured. Remove the flower
from Leuchtenbergia, and very few people indeed would think of calling
it a Cactus, but would probably consider it a short-leaved Yucca. In
habit, in form, in leaf, and in texture, it more resembles a Yucca or an
Agave than anything else, and when first introduced it was considered
such by the Kew authorities until it flowered. The leaves, or rather
tubercles, are sometimes longer and slenderer than in Fig. 74. The
nearest approach to this plant is Mamillaria longimamma, in which the
tubercles are 1 in. or more long, finger-shaped, and crowned with a few
hair-like spines. But the Leuchtenbergia bears its flowers on the ends
of the tubercles, and not from the axils, as in all others. This
peculiarity leads one to infer that tubercles are modified branches, the
spines representing the leaves. Some species of Mamillaria and
Echinocactus develop young plants from the tops of their tubercles; and
this also points to the probability that the latter are branches. In
Leuchtenbergia, the tubercles fall away as the plant increases in
height, leaving a bare, woody stem similar to that of a Yucca.

Cultivation.--The Leuchtenbergia has always been difficult to keep in
health. It thrives best when kept in a warm, sunny house during winter,
and in an exposed, airy, warm position under a frame d