Rhododendron subg. Hymenanthes

'Rhododendron'' subg. Hymenanthes' is a subgenus of the genus Rhododendron'', with a widespread distribution in the temperate Northern Hemisphere. The species are evergreen shrubs and small to medium-sized trees (up to 20 m tall), with medium-sized to large leaves (very large, over 40 cm long, in a few species). The flowers are large, produced in terminal trusses of 5-40 together.

The subgenus includes two sections, 'Rhododendron'' sect. Ponticum, divided into 24 subsections and about 140 species, and (since 2005) Rhododendron sect. Pentanthera'''

Section Ponticum (24 subsections) Section Pentanthera (2 subsections)
 * R. subsect. Arborea (3 species)
 * R. subsect. Argyrophylla (6 species)
 * R. subsect. Auriculata (one species, R. auriculatum)
 * R. subsect. Barbata (2 species)
 * R. subsect. Campanulata (2 species)
 * R. subsect. Campylocarpa (4 species)
 * R. subsect. Falconera (7 species)
 * R. subsect. Fortunea (10 species)
 * R. subsect. Fulgensia (2 species)
 * R. subsect. Fulva (2 species)
 * R. subsect. Glischra (5 species)
 * R. subsect. Grandia (9 species)
 * R. subsect. Griersoniana (one species, R. griersonianum)
 * R. subsect. Irrorata (7 species)
 * R. subsect. Lanata (one species, R. lanatum)
 * R. subsect. Maculifera (6 species)
 * R. subsect. Neriiflora (19 species)
 * R. subsect. Parishia (3 species)
 * R. subsect. Pontica (13 species)
 * R. subsect. Selensia (5 species)
 * R. subsect. Taliensia (20 species)
 * R. subsect. Thomsonia (7 species)
 * R. subsect. Venatora (one species, R. venator)
 * R. subsect. Williamsiana (one species, R. williamsianum)
 * R. subsect. Pentanthera (G. Don) Pojarkova (15 species)
 * R. subsect. Sinensia (one species: Rhododendron molle)

Cultivation
This subgenus includes the majority of the larger evergreen rhododendrons widely grown as ornamental plants. Some species, notably Rhododendron ponticum, have escaped from cultivation and become invasive in some regions such as New Zealand.