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Fagaceae FAMILY Least Concern

Quercus crassifolia

Quercus crassifolia

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

HabitSemi-deciduous Tree
Growth—

Quercus crassifolia is not a very cold-hardy tree, tolerating short periods with temperatures down to around -8°c when dormant. It grows best in areas with hot summers, doing well in mediterranean climates. In areas with cooler summers, such as the maritime regions of the temperate zone, it usually grows less well, often failing to properly ripen its wood and suffering frost damage over the winter[2, 3]. There are specimens in southern Emgland (hardiness zones 7 - 8) more than 18 metres tall[2]. Quercus species generally grow well in a sunny position, though young plants usually tolerate reasonable levels of side shade[3]. They usually prefer a good deep fertile loam which can be on the stiff side[4, 2]. This tree is found in montane cloud forests as well as oak-, pine-oak, and conifer forests on moderately dry slopes. It can inhabit a variety of soils, often growing in volcanic soils of low to neutral pH[5]. Oaks are also often tolerant of moderate exposure, surviving well but being somewhat stunted[3]. Seedlings soon develop a taproot and become intolerant of root disturbance, they should be planted into their permanent positions whilst young[2]. Most Quercus species hybridize freely with other members of the genus[3]. Plants in this genus are notably resistant to honey fungus[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[2]. 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+crassifolia>

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]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.
  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]RHS Dictionary of Plants plus Supplement. 1956 — F. Chittendon. · Oxford University Press · 1951 · ISBN - ↩︎Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaced in 1992 by a new dictionary (see [ 200 ]).
  5. [5]IUCN Red List of Threatened Species — http://www.iucnredlist.org/ ↩︎A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.
  6. [6]Annals of the Missouri Botanical Garden Vol. 89 — Missouri Botanical Garden; St. Louis. · 2002 · http://www.biodiversitylibrary.org · ISBN 0026-6493 ↩︎A botanical journal, it includes a treatment of the oaks of Mexico. It can be downloaded from the Internet
  7. [7]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/
  8. [8]A Modern Herbal. — Grieve. · Penguin · 1984 · ISBN 0-14-046-440-9 ↩︎Not so modern (1930's?) but lots of information, mainly temperate plants.
  9. [9]Companion Planting for Successful Gardening. — Riotte. L. · Garden Way, Vermont, USA. · 1978 · ISBN 0-88266-064-0 ↩︎Fairly good.
  10. [10]Durabilidad natural de la madera de cinco especies de Quercus del estado de Puebla — Salazar J.A.H.; Silva L.V.; Sánchez F.J.Z. · 2001 · http://www.redalyc.org · ISBN 1405-2768 ↩︎
  11. [PFAF]Plants for a Future — pfaf.org ↩︎