This genus, named in honour of Philibert Collet, a French botanist (1643-1718), consists of about a dozen species, all natives of S. America. The following hardy ones have a curious – one of them a unique – appearance out-of-doors in this country. The smaller branches are really spines arranged oppositely, and there is very little or no leafage, especially on old plants. The most conspicuous part of the flower is the bell-shaped or tubular calyx, the petals being very minute or absent. At Kew the three species described below are hardy in sheltered situations and grow well in a sandy, well-drained loam, flowering freely if given a sunny position. Propagation can be effected by means of cuttings.