''Rhododendron''

section Section, Sectioning, or Sectioned may refer to: Arts, entertainment and media * Section (music), a complete, but not independent, musical idea * Section (typography), a subdivision, especially of a chapter, in books and documents ** Section sig ...

''Tsutsusi'' (spelled ''Tsutsuji'' in some older texts) was a

subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

of the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

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 ...

'', commonly referred to as the evergreen

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. In 2005 it was reduced to a section of subgenus ''Azaleastrum''. Containing 80 to 117 species, it includes both

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 ...

and

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 ...

types and is distributed in

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

and

northeastern Asia Northeast Asia or Northeastern Asia is a geographical subregion of Asia. Its northeastern landmass and islands are bounded by the North Pacific Ocean. The term Northeast Asia was popularized during the 1930s by American historian and political s ...

. They are of high cultural importance to the Japanese. Among the species in this genus lie the largest flowering azaleas.

Description

Tsutsusi are characterised by the presence of terminal buds that contain both floral and vegetative shoots. Many also have flattened multicellular ferrugineous (rust coloured) hairs, which can cover the leaves and stems providing a coppery appearance, or pseudoverticillate

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

that are rhombic in shape. However some have hairs confined to the

axils A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, f ...

, or base of floral buds.

Taxonomy

The section has traditionally included two subsections, classified on the basis of their

, young twigs and corolla.

Phylogenetic analysis In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

has confirmed both the

monophyly In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent comm ...

of the section and its subsections.

Subsections

* ''Rhododendron'' subsect. ''Brachycalyx'' Sweet, type '' Rhododendron farrerae''. 15 species. -

, pseudoverticillate, rhombic, crowded at the

shoot apex In cell biology, the meristem is a structure composed of specialized tissue found in plants, consisting of stem cells, known as meristematic cells, which are undifferentiated cells capable of continuous cellular division. These meristematic ce ...

and monomorphic, hairs usually confined to axils, found mainly outside China. * ''Rhododendron'' subsect. ''Tsutsusi'' Sweet, type ''

Rhododendron indicum ''Rhododendron indicum'' is an azalea ''Rhododendron'' species native to Japan (S & W Honshu, Shikoku, Kyushu, Yakushima). Taxonomy It is the type species for the ''Tsutsusi'' Rhododendron sect. Tsutsusi, section and Rhododendron subsect. Tsutsu ...

''. 66 species. - leaves dimorphic, generally deciduous but some apical leaves over winter, young twigs with flattened multicellular hairs that are more widely distributed. The results of molecular analyses reveal that morphological features such as flower colour, corolla size, or whether leaves are mono- or dimorphic, appear to not be very useful in sorting out the phylogenetic relationships within section ''Tsutsusi''.

Etymology

''Tsutsusi'' comes from the Japanese word for Azalea, ''Tsutsuji'' ( つつじ or ツツジ). When Don (1834) described the subdivisions of ''Rhododendron'' he named one of his eight sections, ''Tsutsutsi'' (sic), which he explained was the Chinese name of the first species described (''R. indicum'', originally ''Azalea indica'' L.). The term was first used by

Engelbert Kaempfer Engelbert Kaempfer (16 September 16512 November 1716) was a German natural history, naturalist, physician, exploration, explorer, and writer known for his tour of Russia, Iran, Persia, India, Southeast Asia, and Japan between 1683 and 1693. He ...

(who unlike

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

preferred native names), in Japan and then incorporated into

Michel Adanson Michel Adanson (7 April 17273 August 1806) was an 18th-century French botanist and naturalist who traveled to Senegal to study flora and fauna. He proposed a "natural system" of taxonomy distinct from the binomial system forwarded by Linnaeus. ...

taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

(1763) as ''Tsutsusi'' Kaempf., a genus separate from ''Rhododendron'', in the family Vaccinia or ''Aireles'' (Family 22/58, later Ericaceae). Adanson gives genus ''Tsutsusi'' as synonymous with the earlier ''Azalea'' L. Subsequent authors such as Don (1834) and Candolle (1838) continued the use of the vernacular word ''Tsutsusi'' to describe a subdivision of the genus.

Distribution

Temperate and subtropical regions of China and Japan, but also found occasionally in

Korea Korea is a peninsular region in East Asia consisting of the Korean Peninsula, Jeju Island, and smaller islands. Since the end of World War II in 1945, it has been politically Division of Korea, divided at or near the 38th parallel north, 3 ...

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

Burma Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and ha ...

Laos Laos, officially the Lao People's Democratic Republic (LPDR), is the only landlocked country in Southeast Asia. It is bordered by Myanmar and China to the northwest, Vietnam to the east, Cambodia to the southeast, and Thailand to the west and ...

and

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

Cultivation

The Tsutsusi are amongst the most popular of the cultivated azaleas, and were cultivated in China and Japan prior to their introduction to Europe, and have an important role in the

horticultural Horticulture (from ) is the art and science of growing fruits, vegetables, flowers, trees, shrubs and ornamental plants. Horticulture is commonly associated with the more professional and technical aspects of plant cultivation on a smaller and mo ...

industry. They are grown as landscape plants in appropriate climates, and also as potted plants and

Bonsai Bonsai (; , ) is the Japanese art of Horticulture, growing and shaping miniature trees in containers, with a long documented history of influences and native Japanese development over a thousand years, and with unique aesthetics, cultural hist ...

References

Bibliography

Wilson EH, Rehder A. A MONOGRAPH OF AZALEAS RHODODENDRON SUBGENUS ANTHODENDRON. THE UNIVERSITY PRESS, CAMBRIDGE April 15 1921. PUBLICATIONS OF THE ARNOLD ARBORETUM, No. 9
* * * *

External links

* *
Flora of China

Tropicos
see als
Section Tsutsusi
* {{Taxonbar, from=Q21378817 *Tsutsusi Plant sections