| Melons
and Turk's Caps
By a curious twist of fate, the first cactus ever seen by Europeans
was a member of one of the most peculiar and in many ways anomalous
genus of the family. Brought from the West Indies back to Spain
by Christopher Columbus, this Melocactus (for that’s
what it was) caused something of a sensation, as no one in the
Old World had ever seen a plant even remotely like it. It’s
hard to say definitively what early fifteenth century courtiers
would have thought about such a thing. Would they have wondered
about the plant’s long spines, organized in symmetrical
clusters, or perhaps the remarkable, thickened body, similar
in way to the fleshy root of a beet or turnip, but obviously
designed for life above ground? We can guess, however, about
the most memorable part of the strange new plant, its cephalium,
for it led to its popular name, the “turk’s cap,” and interestingly enough, only Melocactus, and the
ecologically similar genus Discocactus possesses this
type of permanent, apical, hatlike appendage. The other nickname, “melon cactus” (or simply “melon”) presumably
refers to the shape (like an apple—Malus) of a precephalium-sized
plant.
It’s only when a Melocactus reaches maturity
that the cephalium begins to grow. Cylindrical, with a diameter
distinctly smaller than that of the plant body proper, the cephalium
will keep growing for the rest of the plant’s life, but
the body of the plant stops growing the moment the cephalium
starts to form. At a certain stage the cephalium somewhat resembles
a fez sitting on top of a larger head, and thus the nickname.
Adding to the resemblance, the cephaliums of most species of
Melocactus have a covering of orange or red bristles. As the
plants age the cephalium doesn’t increase in girth it
will steadily grow taller, in some species reaching over two
feet in height, out of the body of a globular cactus no more
than a foot or so tall. The cephalium bears small flowers and
fruit that sometimes remain embedded inside, with seeds waiting,
perhaps, for the parent plant to die and provide a bit of organic
matter for them to germinate in their surprisingly inhospitable
environments.
Melocacti generally live in areas we don’t associate with
cacti; the islands of the West Indies, the east coasts of central
and northern South America, places with lots of heat and humidity.
The sites chosen by the plants as habitat, however, offer little
in the way of tropical splendor. A typical Melocactus
site looks something like a parking lot made of huge flat slabs
of stones instead of asphalt, with a few narrow cracks running
here and there. These cracks serve as homes for the plants,
and there often will be fairly good-sized plants, over a foot
tall and wide, growing out of a crack perhaps an inch across.
Many of these sites are close to the sea as well, with the salt
air drying things out even more. Only in a few places in Peru
do melocacti occur at some altitude, growing at as much as 6500
or 7000 feet, but there too they will typically just sit in
tiny fissures in otherwise quite barren expanses of solid rock.
An immature melocactus simply looks like a smallish barrel cactus,
and there is nothing in its appearance that would suggest anything
odd about its cultural needs or ecological propensities. These
will become only too obvious, however, if the plant is subjected
to any degree of cold, with severe damage or death occurring
at temperatures that the great majority of cacti wouldn’t
mind in the least. A few Peruvian and other Andean species (as
well as occasional Brazilian plants) can survive a typical Bay
Area winter without heat if kept dry, but keeping them warm
won’t hurt them either. The root systems of melocacti
are notoriously weak and difficult to reestablish, a consequence,
presumably, of their preferred habitat of next to no soil. Nonetheless,
again as a result of their tropical origins, they need a fair
amount of water, and most prefer more frequent water in winter
than other cacti, say once a month. Their soil mix should be
very quick draining, and they like very bright light, not as
much as the most arid growing cacti, but plenty nonetheless.
Most melocacti look pretty much alike, ribbed globular plant
with outward facing spine clusters distributed along the edges
of the ribs. Some species (such as the aptly named Melocactus
longispinus—sometimes considered just a form of M.
ernestii) have very long spines, but all species are well
armed. Other species that are sometimes encountered in cultivation
include Melocactus bellavistensis (from Peru) and M.
broadwayi and M. intortus, both from the West
Indies. In contrast to the typical cephaliums covered with reddish
bristles, in some melocacti, such as the very rare Brazilian
Melocactus deinacanthus, the upper portion of the cephalium
tends to remain white, with few bristles to poke out beyond
a layer of woolly fibers. A few species have pure white, bristle
free cephaliums, and one of these, Melocactus glaucescens,
combines a cephalium densely covered in curly white wool with
an almost sky-blue body. A last species, Melocactus matanzanus
(from Cuba), resembles the more typical species, with a bristly
orange-red top, except it rarely reaches more than four inches
in diameter, and grows to maturity relatively quickly.
In many ways similar to Melocactus, the genus Discocactus
grows only in Brazil and a few parts of Bolivia and Paraguay
not far from the Brazilian border. Discocactus consists
of round, often somewhat flattened little cacti, rarely more
than six inches in diameter and often less than half that size.
Their bodies look like a small melocactus but in contrast to
that genus, discocacti bear much less fierce spines that adhere
closely to the body of the plant, and in the case of the tiny
Discocactus horstii, are little more than harmless
tufts. Discocactus cephaliums arise from the apex of
the plant, but don’t get very tall and lack the reddish
color or glassy texture of Melocactus cephaliums. Their
proportionately much larger flowers are white and seem more
suited to a columnar cactus than to a squat tiny little plant.
The plant sometimes called Discocactus araneispinus
(also considered just a form of D. zehntneri) clumps
from the base fairly readily, and as a result shows up in the
trade fairly frequently; the other species stay solitary and
mostly have remained rare collector’s items.
These cacti are not the easiest things to grow. They generally
resent being repotted and can take a long time to establish.
Most of them can’t stand cold, or even fairly cool temperatures,
and though they can’t endure long stretches of total dryness,
too much water will rot them, as their weak root systems tend
to be inefficient at sucking up water from wet soil. Melocactus
glaucescens, M. matazanus and Discocactus
araneispinus may be the easiest examples to grow, but even
they aren’t plants for beginners. When grown to maturity,
however, both Melocactus and Discocactus possess
an exotic look shared by no other cacti, and they’ll generally
attract a lot of attention.
The Garden has a very good collection of Melocactus
(20 species out of 31 known). We have a few small ones for sale
from time to time. |
