Zelkova

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Zelkova
Zelkova serrata
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Rosales
Family: Ulmaceae
Genus: Zelkova
Spach

Zelkova (from

Pistillate and hermaphrodite flowers are solitary, or rarely in clusters of two to four, in the upper leaf axils of young branchlets. The fruit is a dry, nut-like drupe with a dorsal keel, produced singly in the leaf axils. The perianth and stigma are persistent. [1][2][3][4]

Species and distribution
Hybrids

Ecology

The genus Zelkova was common throughout northern

Mediterranean islands and the Caucasus, and in eastern Asia where only local glaciation occurred.[5][6] Species of Zelkova were important elements of the vast forests that prevailed throughout the Northern Hemisphere during much of the Cenozoic Period. [7][8][9]

Autumn foliage

Today, the genus comprises six species with disjunct distribution patterns:[10] three in eastern Asia [Zelkova serrata (Thunb.) Makino; Zelkova schneideriana Hand.-Mazz.; and Zelkova sinica C. K. Schneid.], one in southwestern Asia [Zelkova carpinifolia (Pall.) C. Koch] and two on the Mediterranean islands of Sicily (Zelkova sicula Di Pasq., Garfi & Quézel) and Crete [Zelkova abelicea (Lam.) Boiss.]. The oldest fossils attributed to Zelkova date from the early Eocene (55 million years ago) in western North America, where the genus is extinct today. [11] In Bulgaria, Zelkova fossils were found in Paleogene and Neogene layers in the following locations: Zelkova ungeri (Ett.) Kov. — Lozenets, Kurilo, Chukurovo in Sofia Region, Dospey in Samokov Region, Pernik, Pirin Mine in Blagoevgrad Region, Bobov Dol in Kyustendil Region; Zelkova praelonga Berger — Pirin Mine in Blagoevgrad Region. [12]

Zelkova abelicea is endemic to Crete (Greece); it has a fragmentary distribution in the four main mountain regions of Crete (Lefka Ori, Psiloritis, Dikti and Thrypti), between 900 and 1800 m above sea level, which corresponds to the upper timberline.[13] It grows mainly on north-facing slopes or in and around rocky river-beds and gullies which remain moist during dry summers.[14][15] The species is highly endangered through habitat fragmentation and destruction, overgrazing, fire and water stress.[16][15][13]

The Sicilian Zelkova Z. sicula, only discovered in 1991, is listed as an endangered species. The two known populations close to Syracuse (Bosco Pisano and Ciranna) comprise a small number of low shrubs suffering from severe overgrazing; the natural mature size of undamaged specimens is unknown.[17]

Whilst all the known Zelkova taxa are currently in cultivation and in botanic gardens or arboreta, relatively few collections are known to be from wild sourced material or known in the countries of their natural distribution. Z. sicula and Z. abelicea are the two taxa considered to be at most risk of extinction (Critically Endangered and Vulnerable). These two Zelkova species are the two with the most restricted natural distribution—both are small island endemics. The Zelkova with the widest natural distribution, Z. serrata, is also the most common Zelkova in botanic garden collections [18]

Phylogeography, using chloroplast and mitochondrial markers, has mostly focused on the Quaternary and the influence of the cycles of glaciation on species distribution and structure. [19] [20] Phylogeography has, however, also been used to document more ancient patterns,[21][22] with some of them presumably dating as far back as the early Miocene.[23] The retrieval of ancient patterns may be specific to tree species, which are assumed to evolve more slowly than herbaceous plants and shrubs. [24] Zelkova trees live for centuries,[25] which is a good indication that ancient patterns might be recovered using molecular markers.

A few phylogenetic and biogeographical studies have been carried out on Zelkova,[26][8][10][27] but these studies had small sample sizes or weak representation of wild populations. A more comprehensive phylogeographical analysis,[28] based on trnH–psbA, trnL and internal transcribed spacer regions 1 and 2 (ITS1 and ITS2), was the first to use a wide sampling of natural populations from nearly all the disjunct regions where Z. abelicea, Z. carpinifolia and Z. sicula presently grow. It aimed to assess the diversity within and among species using DNA from two cellular compartments that have different modes of inheritance and trace different histories.

Cultivation and uses

Zelkova serrata and Z. carpinifolia are grown as

ornamental trees. [29] The wood is hard, used for making furniture. [29] In Japan, the wood of the keyaki, or Z. serrata is used for making drums, called wadaiko. The most desired drums are hollowed out of a trunk of a zelkova tree, but in many cases, the drum is fashioned from staves of keyaki wood, using the same method as when constructing a barrel.[citation needed
]

Etymology

The name Zelkova derives from the native name of Z. carpinifolia in the Georgian language – one of the Kartvelian languages spoken in the Caucasus, as shown by the Georgian name, ძელქვა (dzelkva), from ძელი (dzeli) meaning 'bar' or 'pillar', and ქვა (kva) meaning 'rock', 'stone' The tree was often used for making rock-hard and durable bars for building and furniture.[30][31]

References

  1. ^ Andrews, S. (1994). Tree of the year: Zelkova. Int. Dendrol. Soc. Yearbook 1993: 11-30.
  2. ^ de Spoelberch, P. (1994). Zelkova: More questions than answers. Int. Dendrol. Soc. Yearbook 1993: 30–33.
  3. ^ Hunt, D. (1994). Beware of the Zelkova. Int. Dendrol. Soc. Yearbook 1993: 33–41.
  4. ISBN 0-00-220013-9
    .
  5. ^ Follieri, M., Magri, D., & Sadori, L. (1986). Late Pleistocene Zelkova Extinction in Central Italy. New Phytologist 103 (1): 269–273 Abstract
  6. ^ Flora of North America: History of North American Vegetation
  7. ^ Mai, D.H. (1995). Tertiäre Vegetationsgeschichte Europas. Methoden und Ergebnisse. Jena, Germany: Gustav Fischer.
  8. ^
    doi:10.1016/j.foreco.2004.05.018
    .
  9. doi:10.1130/2012.CTS004R3C
    .
  10. ^
    doi:10.1111/j.1095-8339.2005.00354.x
    .
  11. ^ Burnham, R.J. (1986). "Foliar morphological analysis of the Ulmoideae (Ulmaceae) from the early Tertiary of western North America". Palaeontographica Abteilung B. 201: 135–167.
  12. ^ Jordanov, Daki (principal editor) (1966). Flora of Bulgaria: Salicaceae до Amaranthaceae. Vol. III. Sofia: Bulgarian Academy of Sciences. p. 155. {{cite book}}: |first= has generic name (help)
  13. ^
    doi:10.1017/s0030605312001275
    .
  14. ^ Egli, B. (1997). "A project for the preservation of Zelkova abelicea (Ulmaceae), a threatened endemic tree species from the mountains of Crete". Bocconea. 5: 505–510.
  15. ^
    S2CID 86160345
    .
  16. ISBN 9789607506047
    .
  17. ^ IUCN: Zelkova sicula
  18. ^ Global Survey of Ex situ Zelkova collections Botanic Gardens Conservation International (BGCI)
  19. S2CID 25027987
    .
  20. PMID 18439840
    .
  21. JSTOR 25065568
    .
  22. S2CID 45076431
    .
  23. doi:10.1016/j.quaint.2009.04.005
    .
  24. S2CID 26333959
    .
  25. doi:10.1016/j.biocon.2012.04.026
    .
  26. S2CID 41755481
    .
  27. S2CID 9935085
    .
  28. S2CID 22408936
    .
  29. ^ a b Kozlowski, Gratzfeld et al., p. 13
  30. ^ Furniture maker: Dennis Young
  31. ^ Zelkova serrata

External links


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