a cluster of pale yellow stamens protruding 1 in. beyond the throat.  The flowers are produced from the sides of the stems, a few inches from the apex, and as they are borne in abundance and last three or four days each, a large specimen makes a very attractive display for several weeks in the summer.  The plant at Kew, a large one, is grafted on the stem of C. Macdonaldiae, which is trained along a rafter, so that the stems of C. Mallisoni hang conspicuously from the roof.

C. serpentinus (serpent-like); Fig. 16.—­When young, the stems of this plant are erect and stout enough to support themselves; but as they lengthen they fall over and grow along the ground, unless supported by a stake or wire; they have numerous ridges, with clusters of hair-like spines, which are usually purplish.  Flowers large, handsome, fragrant; tube 6in, long, green; petals and sepals spreading and forming a star 3 in. in diameter, the petals purplish on the outside, and pinkish-white inside; stamens arranged in a sort of cup 1 in. deep.  This plant rarely produces aerial roots.  Small specimens are ornamental even when not in flower, the bright green, regularly ridged stem, with its numerous little clusters of fine spines, at the base of which are short tufts of a white woolly substance, being both curious and pretty.  It flowers freely every summer.  South America, 1814.

[Illustration:  Fig. 16.—­Cereus serpentinus.]

The globose and columnar stemmed species.

Many of these are unsuited for culture in ordinary plant-houses, whilst others are so rare that, although cultivated in botanical collections, they are not available for ordinary gardens, not being known in the trade.  There are, however, a good many species that may be obtained from dealers in Cactuses, and to these we shall confine ourselves here.  At Kew, the collection of Cereuses is large and diversified, some of the specimens being as tall as the house they are in will allow them to be, and the appearance they present is, to some eyes at least, a very attractive one.  Such plants are:  C. candicans, which is a cluster-stemmed kind, very thick and fleshy, and in shape like an Indian club; C. chilensis;—­with tall hedgehog-skinned stems, the numerous ridges being thickly clothed with clusters of yellowish spines, which become dark brown with age; C. Dyckii, 10 ft. high, the stems thick and fleshy, with ridges 11/2 in. deep; C. gemmatus, a hexagonal, almost naked-stemmed species 10 ft. high; C. strictus, C. peruvianus, C. geometrizans, and C. Jamacaru, which are tall, weird-looking plants, 10 ft. or more high, some of them freely branched.  The following is a selection of the largest-flowered and handsomest kinds: