''Rhododendron'' subg. ''Hymenanthes'' is a subgenus of the genus ''
Rhododendron
''Rhododendron'' (; : ''rhododendra'') is a very large genus of about 1,024 species of woody plants in the Ericaceae, heath family (Ericaceae). They can be either evergreen or deciduous. Most species are native to eastern Asia and the Himalayan ...
'', with a widespread distribution in the temperate
Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...
. The species are
evergreen
In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...
shrub
A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...
s and small to medium-sized
tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...
s (up to 20 m tall), with medium-sized to large leaves (very large, over 40 cm long, in a few species). The
flower
Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...
s 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''][
]
Cultivation
This subgenus includes the majority of the larger evergreen rhododendrons widely grown as ornamental plant
Ornamental plants or ''garden plants'' are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars th ...
s. Some species, notably ''Rhododendron ponticum
''Rhododendron ponticum'', called common rhododendron or pontic rhododendron, is a species of flowering plant in the ''Rhododendron'' genus of the heath family Ericaceae. It is native to the Iberian Peninsula in southwest Europe and the Caucasus ...
'', have escaped from cultivation and become invasive in some regions such as New Zealand
New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
.
Ponticum
Section ''Ponticum'' (24 subsections) includes:
* ''R.'' subsect. ''Arborea'' (4 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'')
Arborea
''Rhododendron subsect. Arborea'' is a subsection of section ''Ponticum'' in ''Hymenanthes'' consisting of 4 species of tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...
s native to East Asia
East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...
.
Campanulata
''Rhododendron subsect. Campanulata'' is a subsection of section ''Ponticum'' in ''Hymenanthes'' consisting of 2 species of shrub
A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...
s native to East Asia
East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...
.
Fortunea
''Rhododendron subsect. Fortunea'' is a subsection of section ''Ponticum'' in ''Hymenanthes'' consisting of 37 species of shrubs or tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...
s native to East Asia
East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...
.
Fulva
''Rhododendron subsect. Fulva'' is a subsection of section ''Ponticum'' in ''Hymenanthes'' comprising 2 species of shrub
A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...
s native to East Asia
East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...
.
Grandia
''Rhododendron subsect. Grandia'' is a subsection of section ''Ponticum'' in ''Hymenanthes'' that comprises 15 species of tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...
s with large leaf blades covered with trichomes native to East Asia
East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...
.
Pontica
''Rhododendron subsect. Pontica'' is a subsection of section ''Ponticum'' in ''Hymenanthes'' consisting of 13 species of shrubs to small tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...
s native to North America, Europe, and East Asia
East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...
.
Pentanthera
''Rhododendron'' sect. ''Pentanthera'' is a section of subgenus ''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 medi ...
'' in the genus ''Rhododendron
''Rhododendron'' (; : ''rhododendra'') is a very large genus of about 1,024 species of woody plants in the Ericaceae, heath family (Ericaceae). They can be either evergreen or deciduous. Most species are native to eastern Asia and the Himalayan ...
''. It comprises 15-16 species of deciduous
In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...
shrub
A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...
s native to temperate regions of the Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...
.
It includes two subsections:
* Pentathera
* Sinensia
Pentanthera
Species include:
Sinensia
Species include:
The section is closely related to sect. ''Rhodora'', differing from it in the flower
Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...
corolla having five fully developed lobes, whereas sect. ''Rhodora'' has the upper three lobes joined into a single three-lipped lobe.
Cultivation
Most (but not all) of the cultivated azalea
Azaleas ( ) are flowering shrubs in the genus ''Rhododendron'', particularly the former sections ''Rhododendron sect. Tsutsusi, Tsutsusi'' (evergreen) and ''Pentanthera'' (deciduous). Azaleas bloom in the spring (April and May in the temperate ...
s belong to species in this section, and hybrids derived from them.
References
Bibliography
*Huxley, A., ed. (1992). ''New RHS Dictionary of Gardening''. Macmillan.
*
Germplasm Resources Information Network: ''Rhododendron'' sect. ''Pentanthera''
External links
Germplasm Resources Information Network: ''Rhododendron'' subgenus ''Hymenanthes''
{{Authority control
*Hymenanthes
Plant subgenera