ONI 
ORC 
are remarkable for tlieir large hispid 
leaves, and the number of white or blue 
flowers they produce. 
ONICIDIUM (Swartz.) Nat. Ord. 
Orchidaceae. This is perhaps the most 
extensive and varied genus in the whole 
order to which it belongs. Some of its 
species have extremely large pseudo- 
bulbs, others have the pseudo-bulbs very 
small; another portion are entirely des¬ 
titute of this organ, and have instead 
thick leathery leaves, which again vary 
in size from two feet long and nearly half 
as much in breadth, to scarcely six inches 
in their greatest measurement; a third 
group are distinguished by their rounded 
rusli-like leaves about the thickness of 
a little finger, and from two to tour teet 
in length. Besides this, quite as much 
disparity exists in the size and colour of 
the flowers and in the length of the 
flower-spike, which in some species will 
attain an extent of twenty feet, while in 
others it is not more than three or four 
inches ; yet every individual is beautiful, 
and worthy a place wherever Orcliidaceee 
are grown. We prefer to cultivate all 
the larger growing kinds in pots, and 
to place them in rather large ones, that 
they may not require frequent shifting, 
which, each time it is performed, inflicts 
a serious check upon the plants, in con¬ 
sequence of the unavoidable breaking of 
the roots; the soil for them should be 
fibrous peat, sphagnum, and rotten wood, 
thoroughly mixed, but not broken finely ; 
this, with abundant drainage, a brisk 
moist temperature in the growing season, 
shade from strong light, a careful pre¬ 
servation from insects and dirt, and a 
moderate rest in winter, will not fail to 
form healthy blooming specimens in a 
short time. The smaller species may 
be placed on blocks. The following are 
a few deserving particular attention: 
ampliatum major , Baueri, bifolium , Gebol- 
letti, crispum, divaricatum, flexuosum, 
Lanceanum , leucochilum, luridum, L. gut- 
taturn , ornithoryncum , papilio, pidvina- 
tmi, sanguineum , and triquetrum . 
ONOCLEA (Linn.) Nat. Or .Polypo- 
diacere. Handsome hardy ferns, suitable 
for the shaded side of rockwork or root- 
work. They should be planted in peat soil. 
ONOSMA (Linn.) Nat. Ord, Bo- 
raginacece. It is only the hardy species 
of these plants that are worth culture ; 
these, however, should always be grown 
among alpines on rockwork; they are 
not particular as to soil, and increase 
themselves rapidly if allowed to shed 
their seeds; giganteum , yellow; Gmelini, 
striped; and tauricum, yellow, are well 
suited for this purpose. 
OPERAS (Linn.) Nat. Ord. Orchi¬ 
dacea. Aery pretty British Orchids. We 
have succeeded in growing them strongly 
in the following manner : the roots were 
potted in rich loam, mixed with nearly 
half its quantity of powdered chalk; 
after flowering in spring, the pots were 
plunged in a shaded dry border, and the 
surface of the soil between and over the 
pots was covered with fresh turf; the 
plants were thus kept moist through the 
summer, and grew well; about Mid¬ 
summer their stems died and fell down, 
and by allowing the turf to remain, the 
roots were sufficiently protected through 
the winter, and shot forth with much 
vigour in the succeeding season. 
OPUNTIA (Tournefort.) Nat Ord. 
Cactacere. The marvellous forms which 
this genus takes in its several members 
is only equalled by the grotesque appear¬ 
ance of its allies of the same order; 
many of them are exceedingly beautiful, 
both in the manner of growing and the 
rich hues of their flowers ; but all are 
armed with spines which the tyro should 
regard with jealous eye, lor they cause 
more pain and irritation if once fixed in 
the skin, than any others over which our 
experience extends. Eor management 
they may be referred to Mammillaria. 
ORBEA (Haworth,) Nat. Order 
Asclepiadaceat. Curious and interesting 
plants, belonging to the same class of 
vegetation as the preceding genus; the 
major part of this one was formerly in¬ 
cluded in the well-known Stapelia, and 
all of them are equally remarkable for 
the rich though lurid colouring of their 
flowers, and the unpleasant scent which 
accompanies them. 
ORCHYS (Linn.) Nat. Ord. Orchi¬ 
dacea. This, the type of the most ex¬ 
traordinary order known in the whole 
