THE GENUS MELOCACTUS.
(From melon, a melon, and Kaktos, a name applied by Theophrastus to a
spiny plant; the species are melon-formed, and their angles are beset
with tufts of spines.)
This genus forms a group of well-marked and curious plants, with stems
similar to those of the globose Echinocactuses and floral characters
quite distinct from all other genera. They cannot be said to possess any
particular beauty, as their stems are stiff and dumpy, their spines
large and rigid, and their flowers small and unattractive. But what is
wanting in beauty of form or colour is atoned for in the cap which
crowns the stem, and forms the flower-head, growing taller and taller
whilst the stem remains stationary, till, under favourable
circumstances, a cylindrical mass of spines and hairs, not unlike a
large bottle-brush, and 1 ft. or more in length, is developed before the
whole plant succumbs to old age. This character belongs more
particularly to M. communis, the commonest species, and the one best
known in English gardens. Additional interest attaches to this species,
from the fact of its having been the first Cactus introduced into
Europe, for we are informed that in the year 1581 living plants of the
Melon Cactus were known in London. Fifty years later, Gerard, the Adam
of English gardening, wrote: "Who can but marvel at the care and
singular workmanship shown in this Thistle, the Melocarduus echinatus,
or Hedgehog Thistle? It groweth upon the cliffes and gravelly grounds
neere unto the seaside in the islands of the West Indies, called St.
Margaret's and St. John's Isle, neere unto Puerto Rico, and other places
in these countries, by the relation of divers that have journied into
these parts who have brought me the plant itself with his seed, the
which would not grow ill my garden, by reason of the coldnesse of the
clymate." After this, the plant appears to have been frequently
cultivated in gardens in this country, and it has only been in recent
years that this and similar curiosities have almost disappeared from all
except botanical collections.
The most prominent distinctive characters of Melocactus reside in the
cap or cluster of spines, wool, and flowers on the summit of the stem.
Thirty species are included in the genus, their stems ranging from 1 ft.
to 3 ft. in height, the ridges straight, and, as a rule, large; whilst
all have stiff stout spines in clusters about 1 in. apart. The small
flowers are succeeded by bright red, cherry-like berries, containing
numerous black, shining seeds. The distribution of the species is over
the hottest parts of some of the West Indian Islands and a few places in
Central and South America.
Cultivation.--The cultivation of the several kinds known in gardens is
as follows: A tropical temperature all the year round, with as much
sunlight as possible, and a moist atmosphere for about three months
during summer, when growth is most active. Very little soil is required,
as the largest stems have comparatively few roots; indeed, imported
stems have been known to live, and even make growth, nearly two years
without pushing a single root; but, of course, this was abnormal, and
was no other than the using-up of the nourishment stored up in the stem
before it was removed from its native home. M. Louis de Smet, a
well-known Ghent nurseryman, who grows a fine collection of Cactuses,
stated that he had kept M. communis a long time in robust health and
growth by feeding it with a very weak solution of salt. Tried at Kew,
this treatment did not appear to make any perceptible difference; but,
bearing in mind that the Turk's-Cap Cactus is found in great abundance
within the reach of sea spray, in some of the West Indian Islands, there
seems much reason in M. de Smet's treatment. The same gentleman informed
us that he had a specimen of this Cactus bearing no less than thirteen
heads. There is, at the time of writing, a specimen at Kew bearing four
fine heads. Large imported plants are very rarely, established; and even
when established, they do not thrive long, owing to the fact that, after
the cap has commenced to form, no further stem-growth is made. Young
plants grow very slowly, a plant 3 ft. across taking, according to Sir W.
Hooker, from 200 to 300 years to reach that size. It has been stated
that grafting is a good plan to adopt for the Melocactus, Mr. F. T.
Palmer, in "Culture des Cactées", recommending the following treatment
for M. communis: Take a Cereus peruvianus of about the same diameter as
that of the base of the Melocactus, cut off the head of the former, but
not so low as to come upon the hard, ligneous axis, and then pare off
the hard epidermis and ribs for about 1 in. Then take off a slice from
the base of the Melocactus, also paring off about 1 in. of the epidermis
all round; place the two together, and bind on firmly with strong
worsted. In warm weather, a union should take place in about two months,
but it will be safest to allow the ligature to remain till growth
commences. The precaution of paring off the hard skin and ribs is
absolutely necessary, as the juicy centre contracts, and the rind, or
epidermis, does not. There would, therefore, be a cavity formed
sufficient to prevent all cohesion, be the graft tied on ever so
tightly.
Large imported stems should be kept perfectly dry for about a fortnight,
and, if they show any signs of rottenness, they should be carefully
examined and the bad portions cut away; exposure to the air for a few
days will generally cause these pared places to callus over. At all
times, even when the stems appear to be in good health, a sharp look-out
should be kept for patches of rottenness in the stem, and especially
about its base.
Propagation.--This is effected by means of seeds, which usually follow
quickly after the flowers produced on cultivated specimens.
Multiplication is also possible by means of offsets, which are formed
about the base of the stem if the top of a growing plant is cut out. The
thirteen-headed plant mentioned above was the result of the removal of
the top of a stem which had developed these lateral growths, and thus
formed a family of red-capped stems; this had, however, taken place
before the plant was removed from its native home. As the cap is the
most remarkable part of M. communis, the purchase of large imported
stems, in preference to young ones raised from seeds, is recommended;
for, as the cap does not form till the stem attains a large size, there
would be small hope of seedlings reaching the flowering stage during a
lifetime.
SPECIES.
M. communis (common); Fig. 54.--Stem from 2 ft. to 3 ft. in diameter,
globose, with from twelve to twenty ridges, and armed with numerous
clusters of strong, short spines, the clusters placed closely together.
On the summit of the stem is a cylindrical crown, about 4 in. broad, and
varying in height from 5 in. to 12 in. This cylinder is composed of a
thick pad of whitish, cotton-like substance, through and beyond which a
great number of bristle-like red spines are developed, the whole being
not unlike a bottle-brush. About the top of this brush-like growth the
flowers are produced. These are small, red, fleshy, and tube-shaped, the
calyx and corolla forming a regular flower, as in a Hyacinth. They are
borne at various times in the year, as long as the cap is growing;
afterwards the latter falls off; and the stem rots. We have a cap that
was cast by an old plant, and which has stood as an ornament on a shelf
in a room for about four years, and is still in perfect condition. In
addition to the name of Turk's-Cap Cactus this plant is also known as
"Englishman's Head" and "Pope's Head." It is a native of several of the
islands of the West Indies, being very abundant in St. Kitt's Island,
where it grows in very dry, barren places, often on bare porous rocks.
[Illustration: FIG. 54. MELOCACTUS COMMUNIS.]
M. depressus (flattened); Bot. Mag. 3691.--Stem broader than high,
deeply cut into about ten broad furrows, along the sharp angles of which
are clusters of pale brown spines, from ½ in. to 1 in. long, arranged in a
star, each cluster 1 in. apart. Instead of the cylinder-like cap of the
Turk's-Cap species, this one has a short, broad tuft of white wool and
red spines, like a skull-cap. The flowers are small, and soon wither,
but remain attached to the oblong berries, which stand erect in a dense
cluster in the centre of the cap, and are of a delicate rose-colour. The
first introduced plant of this was sent home by Mr. Gardner, who
introduced the Epiphyllums and other Cactuses. It flowered on the way to
England, and matured its seeds soon after its arrival. It is a native of
Pernambuco.
M. Miquelii (Miquel's); Fig. 55.--This species appears to have been
introduced in 1838, when two plants of it were sent from the West Indian
Island, St. Croix, to the Hamburg Botanic Gardens. The stem is oval,
dark green, with fourteen well-defined ribs, as regular as if they had
been carved with a knife. The spine-tufts are small; spines short,
black-brown, about nine in each tuft, one of which is central, the
others radiating; they are less than ½ in. long. The "cap" is cylindrical,
3 in. high by 4 in. in diameter, and composed of layers of snow-white
threads, mixed with short reddish bristles.
[Illustration: FIG. 55. MELOCACTUS MIQUELII.]
These three are the only species of Melocactus that have become known in
English gardens, although various other kinds, named M. Lehmanni, M.
Zuccarini, M. Ellemeetii, M. Schlumbergerianus, &c., occur in books.