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Fagaceae FAMILY

Quercus suber

Quercus suber

Edibility
2/5
Medicinal
2/5

Safety & Hazards

All parts of the plant contain tannins. Whilst tannins are found in many foods, and have a range of medicinal uses. They are usually only present in low concentrations. In some foods made from oaks (particularly the seeds), the tannin content can be quite high unless the food is treated to reduce tannin content. Tannins are only of low toxicity and, because of their bitter taste and astringency, are unlikely to be eaten in large quantities. However, if they are taken in excess, they can cause stomach pains; constipation followed by bloody diarrhoea: excessive thirst; and excessive urination[1].

Cultivation Details

HabitEvergreen Tree
GrowthSlow

Quercus suber is not very cold-hardy, tolerating temperatures down to around -8°c for short periods when dormant[2, 3]. It grows best in areas with hot summers, doing well in mediterranean climates. In areas with cooler summers (even if the winters are mild), such as the maritime regions of the temperate zone, it often grows poorly, failing to properly ripen its wood and suffering frost damage over the winter[4, 3]. Plants have a wide tolerance of rainfall - it is well adapted for growing in the drier Mediterranean climates, but also succeeds in parts of northern Portugal with an annual rainfall around 2,400 mm[5]. The sub-species occidentalis is somewhat hardier than the type[4] - there is at least one large healthy specimen of this subspecies at Kew Gardens in London (hardiness zone 7 - 8), it produced some seeds in the hot summer of 1989[PFAF]. Trees grow well in Cornwall where there are many large specimens[4, 6, 7]. Grows best in a sunny to partially shady position[8], though young plants tolerate reasonable levels of side shade[3]. Prefers a good, deep, fertile, well-drained loam, preferably somewhat sandy[5]. Somewhat tolerant of alkaline soils according to one report[9], whilst another says that it requires an acidic soil[8]. Tolerates moderate exposure, surviving well but being somewhat stunted[3]. Established plants are drought tolerant[8]. Cultivated for its bark in Europe, it is the main commercial source of cork[10, 11]. The sub-species occidentalis has slightly thinner bark than the species[4]. Trees have a tendency to form branches quite low down on the trunk - when grown as a source of cork these low branches are normally removed when small in order to maximize cork production[5]. Trees are first harvested when they are 25 - 30 years old[12], and then harvested every 6 - 12 years[13]. The bark must be removed carefully so as not to harm the tree and to ensure future harvests. A large tree can yield up to 1 tonne of cork. Trees are slow-growing but relatively long lived, to about 200 years or more)[5]. The seeds can take one or two growing seasons to mature[5]. The number of acorns produced varies widely from year to year, with occasional very highly productive years followed by others with little or no production[5]. Transplants badly unless it is moved regularly, it should only be moved in September or as growth commences in late spring[4]. Does not fruit well in Britain. Most of the trees grown in Britain as Quercus suber are in fact Quercus suber occidentalis[4]. Hybridizes freely with other members of the genus[3]. This species is notably resistant to honey fungus[14, 3].

Propagation

Seed - it quickly loses viability if it is allowed to dry out. It can be stored moist and cool overwinter but is best sown as soon as it is ripe in an outdoor seed bed, though it must be protected from mice, squirrels etc. Small quantities of seed can be sown in deep pots in a cold frame. Plants produce a deep taproot and need to be planted out into their permanent positions as soon as possible, in fact seed sown in situ will produce the best trees[4]. Trees should not be left in a nursery bed for more than 2 growing seasons without being moved or they will transplant very badly. Cite as: Temperate Plants Database, Ken Fern. temperate.theferns.info. 2026-02-21. <temperate.theferns.info/plant/Quercus+suber>

Pollinators

Wind

References

  1. [1]Poisonous Plants of North Carolina — http://www.ces.ncsu.edu/depts/hort/consumer/poison/poison.htm ↩︎An excellent concise but comprehensive guide to toxic plants that grow in N. Carolina. It lists even those plants that are of very low toxicity, including several well-known food plants such as carrots and potatoes.
  2. [2]Seed Manual for Ornamental Trees and Shrubs. — Gordon. A. G. and Rowe. D. C. F. · HMSO; London · 1982 · ISBN 0-11-710152-4 ↩︎Very comprehensive guide to growing trees and shrubs from seed. Not for the casual reader.
  3. [3]The New RHS Dictionary of Gardening. 1992. — Huxley. A. · MacMillan Press · 1992 · ISBN 0-333-47494-5 ↩︎Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
  4. [4]Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement. — Bean. W. · Murray · 1981 · ISBN - ↩︎A classic with a wealth of information on the plants, but poor on pictures.
  5. [5]European Atlas of Forest Tree Species — San-Miguel-Ayanz, J., de Rigo, D., Caudullo, G., Houston Dur · European Commission · 2016 · http://10.2788/038466 · ISBN 978-92-79-52833-0 ↩︎An excellent guide to the forest trees of Europe. It can be downloaded from the Internet
  6. [6]Shrubs for the Milder Counties. — Arnold-Forster. ↩︎Trees and shrubs that grow well in Cornwall and other mild areas of Britain. Fairly good, a standard reference book.
  7. [7]Trees and Shrubs in Cornwall. — Thurston. ↩︎Trees and shrubs that succeed in Cornwall based on the authors own observations. Good but rather dated.
  8. [8]KemperCentreForHomeGardeningPlantFinder — Missouri Botanical Garden · http://www.mobot.org/gardeninghelp/plantfinder/ ↩︎Basic cultivation details, plant uses, habitat etc for several thousand species of plants, mainly from the temperate zone.
  9. [9]The RHS Gardener's Encyclopedia of Plants and Flowers — Brickell. C. · Dorling Kindersley Publishers Ltd. · 1990 · ISBN 0-86318-386-7 ↩︎Excellent range of photographs, some cultivation details but very little information on plant uses.
  10. [10]Flora Europaea — ? · Cambridge University Press · 1964 · ISBN - ↩︎An immense work in 6 volumes (including the index). The standard reference flora for Europe, it is very terse though and with very little extra information. Not for the casual reader.
  11. [11]Flowers of the Mediterranean. — Polunin. O. and Huxley. A. · Hogarth Press · 1987 · ISBN 0-7012-0784-1 ↩︎A very readable pocket flora that is well illustrated. Gives some information on plant uses.
  12. [12]Flora of the USSR. — Komarov. V. L. · Israel Program for Scientific Translation · 1968 · http://www.biodiversitylibrary.org · ISBN - ↩︎An immense (25 or more large volumes) and not yet completed translation of the Russian flora. Full of information on plant uses and habitats but heavy going for casual readers. It can be downloaded from the Internet.
  13. [13]The Book of Edible Nuts. — Rosengarten. jnr. F. · Walker & Co. · 1984 · ISBN 0802707699 ↩︎A very readable and comprehensive guide. Well illustrated.
  14. [14]The Garden. Volume 112. — RHS. · Royal Horticultural Society · 1987 · ISBN - ↩︎Snippets of information from the magazine of the RHS. In particular, there are articles on plants that are resistant to honey fungus, oriental vegetables, Cimicifuga spp, Passiflora species and Cucurbits.
  15. [15]Mansfeld's Database of Agricultural and Horticultural Plants — http://mansfeld.ipk-gatersleben.de/pls/htmldb_pgrc/f?p=185:3:4292127278597336 ↩︎Terse details of a huge range of useful plants.
  16. [16]Tanaka's Cyclopedia of Edible Plants of the World. — Tanaka. T. & Nakao S. · Keigaku Publishing; Tokyo · 1976 · ISBN - ↩︎The most comprehensive list of edible plants I've come across. Only the briefest entry for each species, though, and some of the entries are more than a little dubious. Not for the casual reader.
  17. [17]Plants for Human Consumption. — Kunkel. G. · Koeltz Scientific Books · 1984 · ISBN 3874292169 ↩︎An excellent book for the dedicated. A comprehensive listing of Latin names with a brief list of edible parts.
  18. [18]A Modern Herbal. — Grieve. · Penguin · 1984 · ISBN 0-14-046-440-9 ↩︎Not so modern (1930's?) but lots of information, mainly temperate plants.
  19. [19]Antibacterial and Antifungal Activities of Some Quercus Species Growing in Turkey — Didem Söhretoğlu; Melike Ekizoğlu; Ekrem Kiliç; M. Koray Sak · 2007 ↩︎
  20. [20]Companion Planting for Successful Gardening. — Riotte. L. · Garden Way, Vermont, USA. · 1978 · ISBN 0-88266-064-0 ↩︎Fairly good.
  21. [21]Flora of Guatemala — Standley P.C. & J. A. Steyermark · 1946 - 1976 · http://www.archive.org/ ↩︎A superb reference, though somewhat dated. Gives lots of plant uses as well as information on plant habit and habitat. The entire flora (13 volumes) can now be downloaded from http://www.archive.org/
  22. [22]Vegetable Tannins — Rottsieper. E.H.W. · The Forestal Land, Timber and Railways Co. Ltd. · 1946 · ISBN - ↩︎A fairly detailed treatise on the major sources of vegetable tannins.
  23. [PFAF]Plants for a Future — pfaf.org ↩︎