Tsutsuji
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''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 sign ...
''Tsutsusi'' (spelled ''Tsutsuji'' in some older texts) was a
subgenus In biology, a subgenus (plural: 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 t ...
of the
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''
Rhododendron ''Rhododendron'' (; from Ancient Greek ''rhódon'' "rose" and ''déndron'' "tree") is a very large genus of about 1,024 species of woody plants in the heath family (Ericaceae). They can be either evergreen or deciduous. Most species are nati ...
'', commonly referred to as the evergreen
azalea Azaleas are flowering shrubs in the genus ''Rhododendron'', particularly the former sections ''Tsutsusi'' (evergreen) and '' Pentanthera'' (deciduous). Azaleas bloom in the spring (April and May in the temperate Northern Hemisphere, and Octob ...
s. In 2005 it was reduced to a section of subgenus ''Azaleastrum''. Containing 80 - 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 leaves, usually in the autumn; to the shedding of petals, aft ...
and
evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...
types and is distributed in
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
,
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
and
northeastern Asia Northeast Asia or Northeastern Asia is a geographical subregion of Asia; its northeastern landmass and islands are bounded by the Pacific Ocean. The term Northeast Asia was popularized during the 1930s by American historian and political scienti ...
. 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 (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
that are rhombic in shape. However some have hairs confined to the
axils A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...
, or base of floral buds.


Taxonomy

The section has traditionally included two subsections, classified on the basis of their
leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
, young twigs and corolla.
Phylogenetic analysis In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
has confirmed both the
monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic grou ...
of the section and its subsections.


Subsections

*''Rhododendron'' subsect. '' Brachycalyx'' Sweet, type '' Rhododendron farrerae''. 15 species. -
leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
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 leaves, usually in the autumn; to the shedding of petals, aft ...
, pseudoverticillate, rhombic, crowded at the shoot apex 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'' section and subsection, and was the original ''Tsutsusi'' describe ...
''. 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 Don, don or DON and variants may refer to: Places *County Donegal, Ireland, Chapman code DON *Don (river), a river in European Russia *Don River (disambiguation), several other rivers with the name *Don, Benin, a town in Benin *Don, Dang, a vill ...
(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 naturalist, physician, explorer and writer known for his tour of Russia, Persia, India, Southeast Asia, and Japan between 1683 and 1693. He wrote two books about his travels. ''A ...
(who unlike
Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
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. ...
's
taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
(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 ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...
,
Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...
,
Burma Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...
,
Laos Laos (, ''Lāo'' )), officially the Lao People's Democratic Republic ( Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ, French: République démocratique populaire lao), is a socialist ...
and
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
.


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 is the branch of agriculture that deals with the art, science, technology, and business of plant cultivation. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and no ...
industry. They are grown as landscape plants in appropriate climates, and also as potted plants and
Bonsai Bonsai ( ja, 盆栽, , tray planting, ) is the Japanese art of growing and training miniature trees in pots, developed from the traditional Chinese art form of ''penjing''. Unlike ''penjing'', which utilizes traditional techniques to produce ...
.


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 ''Rhododendron'' section ''Tsutsusi'' (spelled ''Tsutsuji'' in some older texts) was a subgenus of the genus ''Rhododendron'', commonly referred to as the evergreen azaleas. In 2005 it was reduced to a section of subgenus ''Azaleastrum''. Contai ...
Plant sections