Common Name:

General Information

Quercus crassifolia is a deciduous to semi-deciduous shrub growing 2 - 3 metres tall, or a tree that can grow up to 30 metres tall. The bole can be 100cm in diameter[, ].
The tree is harvested from the wild for local use as a food, medicine and source of materials.
Quercus crassifolia grows widely throughout the montane regions of Mexico and Guatemala, and is typically abundant in cloud forests and pine-oak forests, between elevations of 600 - 3,000 metres across its range. Despite threats from deforestation and climate change, this species remains abundant with good regeneration. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2013)[].

Known 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[].

Botanical References

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Range

C. America - Guatemala, north to northern Mexico

Habitat

Cloud forests and pine-oak forests; at elevations from 600 - 3,000 metres[]. Moist to dry, mountain forest, often or usually associated with pines and often forming extensive forests; at elevations from 1,500 - 2,600 metres[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Semi-deciduous Tree
Height	10.00 m
Pollinators	Wind
Cultivation Status	Wild

Cultivation Details

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[, ]. There are specimens in southern Emgland (hardiness zones 7 - 8) more than 18 metres tall[].
Quercus species generally grow well in a sunny position, though young plants usually tolerate reasonable levels of side shade[]. They usually prefer a good deep fertile loam which can be on the stiff side[, ]. 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[]. Oaks are also often tolerant of moderate exposure, surviving well but being somewhat stunted[].
Seedlings soon develop a taproot and become intolerant of root disturbance, they should be planted into their permanent positions whilst young[].
Most Quercus species hybridize freely with other members of the genus[].
Plants in this genus are notably resistant to honey fungus[].

Edible Uses

The shoots are eaten once cooked, then ground and mixed with corn[]. (This is quite possibly referring to the young seed sprouts[])

The bark is used in the preparation of drinks make from Agave[].

The light brown, ovoid or narrowly ovoid seed is 15 - 18mm long and 10 - 12m wide[].
Although we have no specific information for this species, the seeds of all the species of oak are edible - indeed, several species have been used as staple foods, whilst most if not all have been used for food in times of shortage, when better foods were not available[].
The seed is usually cooked before eating, though it can also be eaten raw. It can be eaten whole, though it is more commonly dried, then ground into a powder and used as a thickening in stews etc or mixed with cereals for making bread.
In some species, especially many of those classified as 'white oaks', the seeds are low in tannins and have a more or less sweet and agreeable flavour. The seed of most species, however, have a very bitter flavour, due especially to the presence of tannins. In these species there are various processes that can remove or at least reduce the amount of these bitter substances (although other water-soluble substances, including some minerals, will also be removed).
Tannins are water-soluble and therefore the easiest way to remove or reduce tannin levels is by soaking in water. A few different methods are listed:-
A traditional method of preparing the seed was to bury it in boggy ground overwinter and allow the wet soil to gradually leach the tannins. The germinating seed was dug up in the spring when it would have lost most of its astringency and bitterness.
Another method was to wrap the seeds in a cloth bag and place them in a stream for several weeks.
Drying the seed and grinding it to a powder before soaking speeds up the process. The fastest method is to use hot water, by cooking the powder and changing the water several times until the cooking water is no longer bitter. Alternatively, you can use cold water (which is reported to produce the best quality flour). In this case, you soak the powdered seed in cold water for 12 - 24 hours then discard the water. Repeat this process for a number of times until the soak water is no longer bitter.

The roasted seed of many Quercus species has been used as a coffee substitute.

Medicinal

The bark can be used for medicinal purposes[]. This report is probably based on the tannins found in the bark which are strongly astringent[].
The bark is used as a mouthwash to relieve gum pain, as a wash to treat various skin disorders[].

Combined with mountain carrizo (botanical name not known), sauco (Sambucus species), zarrza (Rubus species) and melissa (Melissa officinalis), it is used to make an infusion for women to drink after childbirth[].

Any galls produced on the tree are rich in tannins and therefore strongly astringent. They can be used in the treatment of various conditions including haemorrhages, chronic diarrhoea, dysentery, as a wash on cuts and wounds, as a mouthwash to treat toothache or gum problems etc[].

Other Uses

The leaves of most species in this genus are more or less rich in tannins. A mulch of the partially decayed leaves can be placed around vulnerable plants in order to repel slugs, snails, grubs etc, and these will in time break down to add humus and nutrients to the soil. Fresh leaves should be used with caution, however, since as these decay they utilize some of the nitrogen in the soil and thus can inhibit plant growth[, ].
The leaves of this species are large and broad, very thick, handsome and covered beneath with a lax or often very dense, soft felt of brownish colour. These leaves often form dense heaps under the trees in late winter or early spring[].

Oak galls are excrescences that are sometimes produced in great numbers on the tree and are caused by the activity of the larvae of different insects. The insects live inside these galls, obtaining their nutrient therein. When the insect pupates and leaves, the gall can be used as a rich source of tannin, that can also be used as a dyestuff and is also used by many cultures to make ink[, ].
The bark of oak trees is also usually rich in tannins and can be used as a dyestuff and for waterproofing rope[, ].

As a source of wood and lumber the genus Quercus is one of the most important of all groups of trees. We have no specific information for this species, but in general he timber is noted for its strength, durability, and beauty, and is used everywhere for innumerable purposes, ranging from fuel to railroad ties, construction of buildings and ships, interior trim, flooring, and all grades of furniture. The woods of different species vary as to their physical qualities; some of them are very hard and tough, others are lighter in weight, softer, and less tough[].
The wood of this species is very durable[]. It is used for the manufacture of agricultural implements, for support beams in houses, the handles of tools, fence posts etc[, ].
The wood is a favoured fuel - burning well and giving off a lot of heat. It is also used for making a good quality charcoal[, , ].

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[]. Trees should not be left in a nursery bed for more than 2 growing seasons without being moved or they will transplant very badly.