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1900 SUPPLEMENT—RECENT INTRODUCTIONS, &c. 171 
Cacti—continued. 
and~the petals are spread in regular whorls, except in the 
Epiphyllums. Stamens many, springing from the side of 
the tube or throat of the calyx, sometimes joined to the 
petals, generally equal in length; anthers small and oblong. 
Ovary smooth, or*covered with scales and spines, or 
woolly, one-celled; style simple, filiform or cylindrical, 
with a stigma of two or more spreading rays, upon which 
are small papille. Fruit pulpy, smooth, scaly, or spiny, 
the pulp soft and juicy, sweet or acid; and full of numerous 
small, usually black, seeds. 
, Tribe I.—Calyz-tube produced beyond the Ovary. Stem covered 
with Tuber 
cles, or Ribs, bearing Spines. 
1. MELocactus. Stem globose ; flowers in a dense cap-like head, 
composed of layers of bristly wool and slender spines, amongst 
which the small flowers are developed. The cap is pesistent, and 
increases annually with the stem. 
2. MAMILLARIA (including Anhalonium). Stems short, usually 
globose, and covered with tubercles or mamme, rarely ridged, the 
apex bearing spiny cushions; flowers mostly in rings round the 
stem. 
3. PELECYPHORA. Stem small, club-shaped ; tubercles in spiral 
rows, and flattened on the top, where are two rows of short scale- 
like spines. 
4. LEUCHTENBERGIA. Stemi naked at the base; tubercles on 
the upper part large, fleshy, elongated, three-angled, bearing at 
the apex a tuft of long, thin, bristle-like spines. 
5. Ecurnocactus. Stem short, ridged, spiny; calyx-tube of the 
flower large, bell-shaped ; ovary and fruit scaly. 
6. Disocactus. Stem short; calyx-tube thin, the throat filled 
by the stamens ; ovary and fruit smooth. 
7. CEREUS. Stem often-lo: and erect, sometimes scandent, 
branching, ridged, or angular ; flowers from the sides of the stem ; 
calyx-tube elongated and regular ; stamens free. 
8. PHYLLOcACcTUS. Stem flattened, jointed, and notched ; flowers 
from the sides, large, having long, thin tubes, and a regular 
arrangement of the petals. 
9. EPIPHYLLUM. Stem flattened, jointed ; joints short ; flowers 
from the apices of the joints ; calyx-tube short; petals irregular, 
almost bilabiate. 
Tribe II.—Calyz-tube not. produced beyond the Ovary. Stem 
é branching, jointed. 
10. RHIPSALIS. Stem thin and rounded, angular, or flattened, 
bearing tufts of hair when young ; flowers small ; petals spreading ; 
ovary smooth ; fruit a small pea-like berry. 
11. OPUNTIA. Stem jointed ; joints broad and fleshy, or rounded ; 
spines barbed ; flowers large ; it spinous, large, pear-like. 
12, PERESKIA. Stem woody, spiny, branching freely; leaves 
fleshy, large, persistent ; flowers medium in size, in panicles on the 
ends of the branches. 
The above is a key to the genera on the plan of the 
most recent botanical arrangement, but for horticultural 
purposes it is necessary that the two genera Echinopsis 
and Pilocereus should be kept up. They come next to 
Cereus, and are distinguished as follow : ps 
EcHINopsis. Stem as in Echinocactus, but the flowers are pro- 
duced low down from the side of the stem, and the flower-tube is 
long and curved. ~ 
PILOCEREUS. Stem tall, columnar, bearing long silky hairs as 
nay as spines; flowers in a head, on the top of the stem, rarely 
produced. 
With the aid of the above key anyone ought to be able 
to say to what genus a particular Cactus belongs, and by ~ 
referring to the descriptions of the species, he may succeed 
in making out what the plant is. For the classification of 
Cactuses, botanists rely mainly on their floral organs and 
frnit. 
The stems of Cactuses show a very wide range of 
variation in size, in form, and in structure. In size, we 
have the colossal Cereus giganteus, whose straight stems, 
when old, are as firm as iron, and rise with many ascending 
arms, or rear their tall leafless trunks like ships’ masts to 
a height of 60ft. or 70ft. From this we descend through a 
multitude of various shapes and sizes to the tiny tufted 
Mamillarias, no larger'than a lady’s thimble, or the creeping 
Rhipsalis, which lies along the hard ground on which it 
~ 
Cacti—continued. 
grows, and looks like hairy caterpillars. In form, the 
variety is very remarkable. We have the Mistletoe Cactus, ° 
with the appearance of a bunch of Mistletoe, berries and 
all ; the Thimble Cactus ; the Dumpling Cactus; the Melon 
Cactus ; the Turk’s Cap Cactus ; the Rat’s-tail Cactus ; the 
Hedgehog Cactus; all having a resemblance to the things 
whose names they bear. Then there are the Indian Fig 
(Opuntia), with branches like battledores, joined by their 
ends; the Epiphyllum and Phyllocactus, with flattened 
leaf-like stems; the columnar, spiny Cereus, with deeply- 
channelled stems and the appearance of immense candelabra. 
, Totally devoid of leaves, and often skeleton-like in appear- 
ance, these plants have a strange look about them, which is 
suggestive of some fossilised forms of vegetation belonging 
to the past ages. 
The greater part of Cactuses belong to the group with 
tall or elongated stems. ‘It is worthy of remark that as 
the stems advance in age the angles‘fill up, or the 
articulations disappear, in consequence of the slow growth 
of the woody axis and the gradual development of the 
cellular substance; so that, at the end of a number of 
years, all the branches of Cactuses, however angular or 
compressed they originally may haye been, become trunks 
that are either perfectly cylindrical, or which have scarcely 
any visible angles.” : ‘ 
A second large group is that of which the Melon and 
Hedgehog Cactuses are good representatives; these have 
sphere-shaped stems, covered with stout spines. We have 
hitherto spoken of the Cactuses as being without leaves, 
but this is only true of them when in an old or fully- 
developed state.. On many of the stems are found upon 
their surface, or angles, small tubercles, which, when young, 
bear tiny scale-like leaves. These, however, soon wither and 
fall off, so that, to all appearance, leaves are never present 
on these plants. There is one exception, however, in the 
Barbados Gooseberry (Pereskia), which bears true and 
persistent leaves; but these may be considered anomalous 
in the order. 
The term “succulent” is applied to Cactuses because of - 
the large proportion of cellular tissue, i.e., flesh, of their 
stems, as compared with the woody portion, In some of 
them, when young, the woody system appears to be 
altogether absent, and they have the appearance of a mass 
of fleshy matter, like a Vegetable Marrow. This succulent 
“ mass is protected by a tough skin, often of leather-like 
firmness, and almost without the little perforations called 
breathing and evaporating pores, which in other plants are 
very numerous. This enables the Cactuses to sustain without 
suffering the full ardour of the burning sun and parched-up 
nature of the soil peculiar to the countries of which they 
are native. Nature has endowed Cactuses with a skin 
similar to that with which she clothes many succulent 
fruits, such as the Apple, Plum, Peach, &c., to which the 
sun’s powerful rays are necessary for their growth and 
ripening. 
The spiny coat of the majority of Cactuses is no doubt 
intended to serve as a protection against the wild animals 
inhabiting with them the sterile plains of America, and to 
whom the cool, watery flesh of the Cactus would otherwise 
fall a prey. Indeed, these spines are not sufficient to 
prevent some animals from obtaining the watery insides of 
these plants, for we read that mules and wild horses kick 
them open and greedily devour their succulent flesh. It 
has also been suggested that the spines are intended to 
serve the plants as a sort of shade from the powerful 
sunshine, as they often spread over and interlace about the 
stems. 
There is nothing in the nature or the requirements of 
Cactuses that should render their successful management 
beyond the means of anyone possessing a small, heated 
greenhouse, or even a window recess to which sunlight 
can be admitted during some portion of the day. In large 
establishments, such as Kew, it is possible to provide 
