Most of the species have purple or whitish flowers, but some, such as _R. chrysanthemum_, and _R. anthopogon_, have yellow flowers; _R. ferrugineum_ and _R. hirsutum_, have bright pink or rose-coloured flowers; and those of _R. arboreum_ the Nepaul tree Rhododendron, are of a rich scarlet. The commonest small kinds are _R. ferrugineum_ and _R. hirsutum_, both dwarf shrubs and natives of the north of Europe, with funnel-shaped corollas, and leaves dotted on the under surface. They are so much alike as scarcely to be distinguished at first sight, but on examination the leaves of _R. ferrugineum_ will be found to have brown dots, and to be plain on the margin; while those of _R. hirsutum_ have white dots and are fringed with fine hairs. Of all the species of the genus, those which differ most widely from the others are the Indian kinds. Of these _R. arboreum_ has a ten-celled capsule, and the segments of the corolla two-lobed with waved margins. The leaves are long and silvery beneath; and the capsules, the peduncles, and the calyxes, are all woolly. In _R. campanulatum_, a splendid species with very large flowers, the capsule is six-celled, the leaves are somewhat cordate at the base, and the bracts are fringed; and in _R. anthopogon_ the corolla has a cylindrical tube, woolly inside, and a small but spreading limb, cut into five lobes. There are eight stamens, and the capsule is five-celled. _R. Camtschaticum_, _R. Chamæcistus_, and _R. dauricum_ differ from the preceding species in having their corollas rotate, that is, wheel-shaped. The last of these kinds is a favourite greenhouse shrub, from its flowering under shelter in winter. In the open ground it flowers in March. The species has rose-coloured flowers which appear before the leaves; and leaves which turn red in autumn before they fall. The roots are knobbed and fibrous; and the stems are twisted and knobbed in a wild state. There is a variety _R. d. atrovirens_ which has purple flowers, and evergreen leaves, and which is hardier than the species.