If the stems are more curious than beautiful, the flowers of the majority of the species of Cactuses are unsurpassed, as regards size and form, and brilliancy and variety in colour, by any other family of plants, not even excluding Orchids.  In size some of the flowers equal those of the Queen of Water Lilies (Victoria regia), whilst the colours vary from the purest white to brilliant crimson and deep yellow.  Some of them are also deliciously fragrant.  Those kinds which expand their huge blossoms only at night are particularly interesting; and in the early days of Cactus culture the flowering of one of these was a great event in English gardens.

Of the many collections of Cactuses formed many years ago in England, that at Kew is the only one that still exists.  This collection has always been rich in the number of species it contained; at the present time the number of kinds cultivated there is about 500.  Mr. Peacock, of Hammersmith, also has a large collection of Cactuses, many of which he has at various times exhibited in public places, such as the Crystal Palace, and the large conservatory attached to the Royal Horticultural Society’s Gardens at South Kensington.  Other smaller collections are cultivated in the Botanic Gardens at Oxford, Cambridge, Glasnevin, and Edinburgh.

A great point in favour of the plants of the Cactus family for gardens of small size, and even for window gardening—­a modest phase of plant culture which has made much progress in recent years—­is the simpleness of their requirements under cultivation.  No plants give so much pleasure in return for so small an amount of attention as do these.  Their peculiarly tough-skinned succulent stems enable them to go for an extraordinary length of time without water; indeed, it may be said that the treatment most suitable for many of them during the greater portion of the year is such as would be fatal to most other plants.  Cactuses are children of the dry barren plains and mountain sides, living where scarcely any other form of vegetation could find nourishment, and thriving with the scorching heat of the sun over their heads, and their roots buried in the dry, hungry soil, or rocks which afford them anchorage and food.

In beauty and variety of flowers, in the remarkable forms of their stems, in the simple nature of their requirements, and in the other points of special interest which characterise this family, and which supply the cultivator and student with an unfailing source of pleasure and instruction, the Cactus family is peculiarly rich.

CHAPTER II.

BOTANICAL CHARACTERS.

Although strictly botanical information may be considered as falling outside the limits of a treatise intended only for the cultivator, yet a short account of the principal characters by which Cactuses are grouped and classified may not be without interest.