Quercus ithaburensis Decne.

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Credits

Allen Coombes & Roderick Cameron (2021)

Recommended citation
Coombes, A. & Cameron, R. (2021), 'Quercus ithaburensis' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/quercus/quercus-ithaburensis/). Accessed 2021-12-01.

Genus

  • Quercus
  • Subgen. Cerris, Sect. Cerris

Common Names

  • Tabor Oak
  • Mount Tabor Oak

Synonyms

  • Quercus aegilops subsp. ithaburensis (Decne.) Eig
  • Quercus aegilops var. ithaburensis (Decne.) Boiss.

Other taxa in genus

Glossary

herbarium
A collection of preserved plant specimens; also the building in which such specimens are housed.
IUCN
World Conservation Union (formerly the International Union for the Conservation of Nature).
Least Concern
IUCN Red List conservation category: ‘does not qualify for Critically Endangered Endangered Vulnerable or Near Threatened. Widespread and abundant taxa are included in this category.’ ‘Lower Risk’ was formerly used and many tree species are still so-categorised in the Red List.
section
(sect.) Subdivision of a genus.
acorn
Fruit of Quercus; a single-seeded nut set in a woody cupule.
cupule
Cup-shaped structure formed from coalescent bracts. Typical of Fagaceae and Nothofagaceae. May be dehiscent (as in e.g. Castanea) or indehiscent (as in e.g. Quercus).
dbh
Diameter (of trunk) at breast height. Breast height is defined as 4.5 feet (1.37 m) above the ground.
introgression
Incorporation of genes from one species into the genotype of another through repeated hybridisation or repetitive backcrossing between a hybrid and one of its parents.
morphology
The visible form of an organism.
subspecies
(subsp.) Taxonomic rank for a group of organisms showing the principal characters of a species but with significant definable morphological differentiation. A subspecies occurs in populations that can occupy a distinct geographical range or habitat.

Credits

Allen Coombes & Roderick Cameron (2021)

Recommended citation
Coombes, A. & Cameron, R. (2021), 'Quercus ithaburensis' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/quercus/quercus-ithaburensis/). Accessed 2021-12-01.

Deciduous tree, generally 4–6 m tall, sometimes reaching 15 m in height. Trunk up to 0.5–1 m in diameter, bark dark brown or grey, smooth at first later becoming slightly fissured and corky with many protuberances. Crown rounded or broadly ovoid, branches grey, forming a spreading habit. Young twigs grey-tomentose with stellate hairs, becoming glabrescent depending on climatic conditions, in habitats with mild winters persisting longer. Buds ovoid with appressed scales, hairy mainly at margin. Leaves broad-ovate, 6–10 long × 3–6 m wide, leathery, varying in size and shape on the same tree, base indented, sometimes Z-shaped, obtuse or acute at apex; leaves emerge covered above and below with abundant whitish or yellowish white tomentum, glabrescent above, becoming dark green, somewhat shining, pale and stellate-pubescent above, rarely also pubescent above, with 6–10 lateral nerves ending in triangular, often aristate or long-mucronate teeth, unequal in size and shape; foliage late in falling, rarely in warm winters semipersistent; petiole 1–2 cm long, densely hairy. Acorns solitary or in clusters of 2 or 3, sessile or borne on very short and thick peduncle, ripen in second year; cupule large, 2.5–3 cm deep × 3.5 cm diameter, hemispherical or turbinate, scales thick, lanceolate, recurved, spreading, deflexed or erect, often upper scales long, recurved, the lower short, erect; nut cylindrical, 2–5 cm long × 1.6–1.8 cm wide, one third enclosed in cupule, rarely half. (Zohary & Feinbrun-Dotan 2015le Hardÿ de Beaulieu & Lamant 2010Stephan 2017)

Distribution  IsraelJordanLebanonSyriaTurkey Southeast Anatolia

Habitat Forests and forest remnants on various soils (rendzina, terra rossa, basalt, sandy-loam soils) 0–500(–1000) m above sea level. Trees are often found isolated or grouped in small clusters, rarely mixed with other oak species like Quercus coccifera or Q. infectoria, and other accompanying species like Styrax officinialis, Pistacia palaestina, Pyrus syriaca, and Crataegus azarolus var. aronia.

USDA Hardiness Zone 6

RHS Hardiness Rating H7

Conservation status Least concern (LC)

Taxonomic note For some authors, Q. ithaburensis includes the subspecies macrolepis, but we follow Avisahai (2016) and others in considering Q. macrolepis a valid species (see entry in TSO). Zohary & Feinbrun-Dotan (2015) recognize five varieties of Q. ithaburensis, distinguished by charactersitics of the acorn and cupule: var. calliprinoides, var. subcalva, var. subinclusa, var. dolicholepis, and var. ithaburensis. They found that fruit characters are faily constant at least in the first generation. The var. ithaburensis is the most widespread and dominates in individual populations. Bean (1976) suggested that a specimen in the Kew Herbarium with thread-like scales represents var. dolicholepis.

Though it was named after a low hill in northern Israel, Tabor Oak is by no means restricted to that location. One of the southernmost deciduous oak species in the Eastern Mediterranean basin, Q. ithaburensis is found mainly in Israel, where it is a leading plant in various oak forest communities, but also further inland in Palestine and Jordan, and its range extends north through Lebanon and Syria to southern Turkey. It is a thermophilous (read ‘sun-loving’) species and prefers mild winters, so is found at low altitudes from sea level (or even below that in the Jordan Valley) up to 600 m (roughly the elevation of the summit of the eponymous Mount Tabor), and in rare instances up to 1000 m. Though in natural habitat some trees are clearly deciduous, others retain their foliage through most of the year, with only a short duration of leaflessness. Ne’Eman (1993) even hypothesized that the species is in an evolutionary transition from deciduous to evergreen. It has also adapted to dry conditions and is relatively drought tolerant, to the extent that its acorns are able to endure significant water loss before losing viability (Ganatsas et al. 2017). Due to its shallow root system it does not do well in heavy soils and thrives mainly in mature deep soils, whether basaltic or limestone. It is found in fertile plains like the Sharon Plain, Lower Galilee, and the Jordan Valley, as well as the Lower Litani watershed and the Akkar plateau on the coastal zones of Lebanon and Syria (Stephan 2017). Together with its close allies Q. macrolepis and Q. brantii, it forms the Valonia or Aegilops group of Section Cerris oaks (see entry in TSO for Q. macrolepis).

Tabor Oak has had a rough time of it in the Anthropocene: since the Neolithic it has suffered from habitat reduction due to human settlement and agricultural expansion in the coastal zones it inhabits. In the Sharon Plain, in particular, the thick oak forests that at one time prevailed (and may have been the origin of the name ‘Sharon’) have been cut down repeatedly, first by Ibrahim Pasha of Egypt in the 1830s for timber for fuel and ship construction, then by the Ottomans in the first two decades of the 20th century for railway construction and fuel for steam engines, and lastly in the period leading up to the establishment of the state of Israel in 1948, when a large part of the forest was transformed into farming areas (Barnea 2019). Jean Stephan (2017) expressed concern at low regeneration rates caused by pest outbreaks, low acorn productivity, and overgrazing, but recognized that trees are being preserved for shade and are rarely pruned for fuel or grazing. Barnea (2019) is more optimistic and notes that distribution of acorns by birds and animals, together with tree planting in private and public areas, is contributing to reforestation in the Sharon area. Monumental trees, which can reach a diameter of 2.50 m and a height of 20 m, are preserved near religious sites, and the Israel Oak Registry records many of these specimens as well as new plantings (Barnea 2018). IUCN’s Least Concern assessment (Gorener & Jerome 2018) is based primarily on populations in Europe of Q. macrolepis, treated by the authors as a subspecies of Q. ithaburensis; they recognize, however, that large populations of Q. ithaburensis have been almost entirely removed from the Sharon Plain.

Michael Avishai (2016) suggested that the relatively large acorns of Q. ithaburensis and its allies Q. macrolepis and Q. brantii were an important food source for early human populations. Domestication and dispersal by ancient cultures may have influenced the morphology, distribution, and evolution of these species. Its wood makes excellent charcoal and is well suited for construction (characteristics that almost spelled doom for the species in Sharon) and its acorn cups are used in the leather industry due to their high tannin content (le Hardÿ de Beaulieu & Lamant 2010).

Despite its predilection for sunshine, Tabor Oak is found in several collections in the United Kingdom, including Kew, where a specimen had reached 15 m × 52 cm dbh in 2010, and is the current UK and Ireland champion (Tree Register 2021). A smaller tree there derives from a collection by Major Tom Spring-Smyth in the Golan area of Israel in 1981 (H. Baldwin, pers. comm.). A small tree that grew for many years unnamed at Sir Harold Hillier Gardens was from a collection by E.K. Balls. It is also to be seen in European collections, though at Arboretum de la Bergerette in France it is reported to grow very slowly (Haddock 2012). One would expect it to thrive in sunny California, and indeed a couple of fifty-year-old specimen grow at Shields Oak Grave at UC Davis. Dave Muffly (2021) reports that some seedlings from their acorns come true, while others show introgression with Section Cerris oaks in the arboretum, such as Q. suber. He suggests the species has fairly limited potential for urban forestry in California, but might prosper in parks and arboreta. Tabor Oak seedlings have proven tricky to grown in nursery settings, but with proper care achieve good survivability. Several trees are grown in the Jerusalem Botanical Gardens, some from seed collected in Israel (The Jerusalem Botanical Gardens 2021).

Described by Joseph Decaisne in 1835, from a specimen collected on Mount Tabor by Nicolas Bové. The epithet is the Latinized demonym meaning ‘from Tabor’.