The Beech Tree (Fagus sylvatica)

Above: European Beech, Fagus sylvatica. It is naturally found in temperate European climates, including southern England as here, but is also planted more widely as an ornamental.Other species of the genus Fagus include beech trees found in Asia and North America. There are about a dozen or so species in these genus.

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Form. Beech, Fagus sylvatica, is a large tree, reaching 30 to 40 m in height (occasionally 50 m) and 5.5 m in girth. Beech usually lives for 150 to 300 years, but coppiced/pollarded individuals may occasionally reach 550 years. There is almost always a single stem. Chromosome number = 24. A stately tree with a large column-like bole, up to 42.5 m tall with a canopy up to 40 m in diameter and trunks over 6 m in girth. Shed their lower branches when growing in woods. Beech trees exhibit monopodial growth.

Leaves. The leaves are alternate and ovate (egg-shaped in contour) to elliptic and 4 to 10 cm long (sometimes growing larger in trees which have been trimmed) with petioles 5 to 15 mm in length. The leaf margins are wavy. In shaded branches, the leaves form a monolayer with fewer and larger leaves per branch; whilst in sunny conditions the leaves form multiple layers. Shaded leaves have fewer layers of photosynthetic palisade mesenchyme cells. Sun leaves have longer petioles (possibly to increase movements in the wind for better mixing of air layers to supply more carbon dioxide for photosynthesis).

The leaves are very tough on trees growing in the open, where trees are more likely to be buffeted by the elements and subject to dehydration; more delicate when growing in woods. The leaves twist on their stalks to face the Sun. The young leaves open by April and are soft, pale and vibrant green at first, toughening and darkening with age. The darker green Summer leaves form a dense canopy. The Autumn leaves display spectacular color changes, turning yellow, then orange, russet and copper. In the copper beech, the leaves are a copper, red or dark purple color due to accessory pigments that shield the chlorophyll. Copper beeches are at an advantage in exposed places subject to high levels of ultraviolet light, since the red pigment shields the chlorophyll from Sun damage.

Bark. The bark is distinctive: smooth (sometimes slightly roughened), thin and silver-grey bark (often tinged green by epiphytic algae). The distinctive buds are long (1-2 cm) and fusiform (spindle-shaped) and reddish-brown in color. The new twigs are dull purplish-brown, turning greyer in their second year. The bark is only about 6 mm thick on a trunk of 30 cm (one foot) diameter. Type 3 lenticels, in which loose nonsuberised tissue alternates with compact suberized tissue with the compact tissue forming closing layers and a very definite annual layering.

Flowers. Wind-pollinated. The tree is monoecious (having separate male and female flowers on the same individual) with male and female flowers occurring on the same branch. This tree is protogynous: female flowers mature first, in April, followed by male flowers, so as to reduce the odds of self-pollination. The male catkins are in groups of 2 or 3 hanging downwards on slender drooping stalks and each is a tassel of about 15 greenish flowers. Each stalk bears 2 or 3 long and slender scale leaves They have 8-16 stamens and 4-7 perianth (sepal/petal or tepal) lobes.

The female flowers usually occur in pairs and each has three styles, an inferior ovary, and 4-5 perianth lobes. The pair is surrounded by a scaly cupule with 4 valves (consisting of the involucre / whorls of bracts). The female flowers are bristly, oval balls borne on a stem with protruding long slender styles and appear by May. The female flowers mature 2-3 days before the male flowers. The floral formulae are essentially the same as those for Quercus (oak).

The first flowers form at around 40 to 80 years of age (longer in denser more shaded and more competitive stands).

Fruit. The fruit (beech mast) is an ovoid 3-angled nut (about 1 to 2 cm long) and is edible. Usually a pair of nuts (derived from the usual paired female flowers) but occasionally as many as 5 are enclosed in the cupule which is usually 2-5 cm long and covered in prickly awl-shaped spines.

The woody bracts of the female flower form a rough, bristly brown husk that contains two 3-sided nuts which ripen by October. A full crop of nuts are produced every five years and trees produce their best crops when over 50 years of age. The ripe husks split into fall sections, exposing the nuts, whilst still on the tree, and then the whole falls and the nuts detach from the bracts later. In historic times, the nuts were used as a food for pigs, but they are quite edible and taste like a cross between hazel and almond nuts. In most years, however, most of the nuts are empty shells, but in good years they are plentiful.

The flowers of beech are more-or-less self-incompatible and isolated trees that rely on self-pollination produce mainly empty seeds. Seeds are generally produced every other year 9 (or 4 to 8 years in mainland Europe). Every 15 years or so a mast year occurs, in which the entire beech tree population produces an especially large crop of nuts; ensuring that enough survive being eaten to germinate. Masting, however, diverts resources and during mast years vegetative growth is considerably reduced.

Squirrels, Jays, Nuthatch (Sitta europaea) and Coal Tits have been known to cache beech nuts over winter and thus disperse the seeds when caches become forgotten or abandoned. A beech nut weighs about 225 mg on average. Chilling over winter is required to break seed dormancy allowing germination the following spring. Fagus sylvatica does not maintain a seed bank in the soil.

The same tree (2 years later in 2020) having lost more of its crown (below).

Twigs. Long pointed chestnut-brown buds grow on dark purplish winter twigs.

Habitat. Beech prefers well-drained soils with a pH between 3.5 and 8.5, such as limestone, sandy/stony soils, shallow soils and sandstone. In base-rich soils it occurs along with Mercurialis perennis (Dog's Mercury) and as the pH drops and exposure
increases it gives way to yew (Taxus baccata). In deeper, moister and more base-poor soils it grows alongside Rubus fruticosus (blackberry) and holy (Ilex aquifolium). Native to SE-England and continental Europe. Thrives on chalky soils, well-drained loams and sandy soils, shade-tolerant.

Beech is susceptible to Spring frosts, but is otherwise hardy. Beech is very shade-tolerant and 'dwarf' plants which are shaded may grow up rapidly to fill storm gaps left by windthrown trees. There are a number of planted cultivars, including 'Purpurea' the attractive purple or copper beech.

Wood. White to pale brown; diffuse porous (the diameter of the xylem vessels formed in spring and summer are approximately the same). The rays may be up to 25 cells wide and may be one mm or more in height. Red heartwood may be present. Beech wood is of the diffuse porous type. In diffuse porous wood the early xylem vessels (those formed in Spring) are no larger or only slightly larger than those formed later in the year (though annual growth rings are still visible).

Roots. The roots are shallow and slow to grow into new soil, making the tree vulnerable to drought and also to toppling or windthrow when growing on slopes. Adventitious roots can be produced on branches which contact the ground, resulting in self-layering (growth of a new tree where a living branch touches the ground). In trees which are broken or partly uprooted, reiterative sprouts form: new shoots replace the parent axis by growing vertically. The shallow roots are often visible for some distance from the tree on the surface of the soil. The roots are short, slow-growing and bear many branches and so utilize a small soil volume more effectively (the preferred soil types of beech trees are often shallow soils).

This beech tree was colossal! On closer inspection it looks as if two, or even three, main stems have fused / grafted together.

Below: another large Beech Tree in the same stand.

Beechwood Ecology

Here we shall consider the adaptations of some of the organisms that occupy niches in the beechwood ecosystem.

First of all, Fagus sylvatica itself, the climax species in this ecosystem. Fagus sylvatica is monecious (it has male and female flowers on the same plant), protogynous (the female flowers ripen first, reducing the likelihood of self-pollination which results in a high number of sterile fruit) and wind pollinated (its flowers have reduced perianths/petals since they no longer need to attract insects). Mutualisatic fungi associate symbiotically with the roots as mycorrhiza (forming an ectomycorrhizal Hartig net) and supply the tree with minerals, especially phosphorus and nitrogen, in exchange for carbon fixed by the tree in photosynthesis. Beeches are very conservative in their use of water but very susceptible to even temporary flooding.

The dense canopy of Fagus sylvatica is extremely good at intercepting light and beech trees have shallow highly-branching roots, allowing them to exploit shallow well-drained sandy/stony/calcareous soils and they are very efficient at absorbing water and minerals from a small soil volume. (However, beech trees are not very resistant to flooding). Beech leaves are also slow to decay, apparently because earthworms avoid them and a thick layer of humus accumulates beneath beech trees into which the tree grows its feeder roots to absorb the nutrients that are slowly released as the leaves do eventually decompose. These factors combine to inhibit the growth of green plants beneath beech trees. In summer beech woods can be very dark and foreboding but are also quite open beneath the canopy.

Above: The Violet Helleborine (Epipactis purpurata) is one of the few flowering plants that can grow beneath the shade of beech trees and is often one of the few plants growing in the most shaded parts of a beechwood, along with Epipogium aphyllum (Ghost Orchid), Neottia nidus-avis (Bird's-nest Orchid) and Cephalanthera damasonium (White Helleborine). These orchids can all thrive in heavy shade because they are mycoheterotrophic, that is they can feed on fungi!

Orchidaceous mycorrhizas. The germlings of all terrestrial orchids rely on fungi to supply them with carbon, since the minute dust seeds of orchids carry very few nutrient reserves. Some orchids will spend one or more years below ground, either as seedlings or as adult rootstocks and during this time they feed upon fungi. However, many orchids will apparently cease to feed in this way once they emerge above ground, but achlorophyllous forms remain dependent on the fungi and mixotrophs have variable dependence according to available light levels. Fungal hyphae in the soil entering the orchid form coiled structures called pelotons inside the orchid's cells. After a short time, however, the pelotons are digested and utilized as nourishment for the orchid cells: the orchid is literally eating the fungi. A variety of fungi may be utilized, including species parasitic on trees, those that form mutualistic symbiotic mycorrhizas with trees and saprotrophs that feed on decaying organic matter. In those orchids adapted to dark habitats they preferentially associate with the mycorrhiza of woody plants.

Neottia nidus-avis contains chlorophyll type a (despite its brown appearance) but is not photosynthetic and can not evolve oxygen in the light since it lacks a functional photosystem II. Instead, however, it can make ATP using energy from sunlight by cyclic photophosphorylation utilizing PS I. Thus it can obtain energy from sunlight, but needs its fungal host to supply carbon.

Epipactis purpurata is a facultative mycoheterotroph, meaning it can grow and flower without fungi in bright light but in deep shade it must rely on fungi in its roots and rhizome from which it steals mineral nutrients. Such plants are also called mixotrophs, since they obtain some nutrient from their own photosynthesis and some from the fungi they 'predate'. In particular it is often associated with beech trees and associates with the fungus Russula heterophylla which is itself forms symbiotic mycorrhiza with Fagus sylvatica roots. The tree supplies the fungus with carbon in return for minerals, particularly phosphorus and nitrogen. Consequently, the orchid is also parasitizing the beech tree via the fungus. Some forms of Epipactis purpurata lack chlorophyll altogether and so are totally reliant on the fungi (these forms are usually smaller however). The dense leaf litter in beechwoods ensure a good humus layer supplying mineral nutrients to the fungi.

Above: Cephalanthera damasonium (White Helleborine) obtains up to 85% of its carbon from fungi when growing in dark beech forests, but as little as 33% when growing in open pine forests.

Above: Ganoderma applanatum is a bracket fungi that parasitises Fagus sylvatica, feeding on old and unhealthy trees. It secrete cellulases to digest the cellulose component of the host cell walls. It uses the elevation of the tree trunk to help disperse its spores which stain the bark red.

Above: Amanita citrina (False Deathcap) frequently spores beneath Fagus sylvatica and is reported to form ectomycorrhizal associations with Beech roots, as well as with Birch and Oak. An ectomycorrhiza is a different root-fungus association than that seen in orchids. In the ectomycorrhiza, the fungal hyphae form a sheath around the root and then their hyphae penetrate the intercellular spaces of the root, forming a Hartig net.

Note: the term 'Hartig net' is sometimes refers specifically to that part of the fungus in-between the cells of the plant root as opposed to the external fungal sheath.

Above: Coprinus picaceus (= Coprinopsis picacea, Magpie Ink Cap). This fungus is also commonly found beneath beech trees and may well be tapping into the mycorrhiza in much the same was as Amanita citrina - establishing beyond doubt which fungi connect to which plants is by no means easy.

Examples of Beechwood Animals

The fallen cupules and the dense leaf litter in beechwoods provide a good habitat for pseudoscorpions, springtails and mites. Pseudoscorpions are arachnids that resemble scorpions, with a pair of pincers, but have no tail and they are only a few millimeters long! (The largest species known in the world to date is only about 15 mm long and must are much smaller). Examples of pseudoscorpions in beechwoods include Roncus lubricus (Reddish two-eyed Chelifer) is found in the leaf litter of beech, poplar and sycamore; whilst Lamprochernes chyzeri (Chyzer's Shing Claw) can be found beneath the bark of old and decaying trees, especially aspen, but also beech and birch. Pseudoscorpions are predators, feeding on small arthropods, including springtails and mites. The claws (pedipalps) are usually equipped with posion galnds and are used to immobilise or kill prey. The chelicerae (mouthparts) then break open the exoskeleton of the prey, digestive fluids are injected and the resulting juices strained out.

Certain species of mite (Acari) form galls on Fagus sylvatica. These tend to appear as hairy patches on one or other side of the leaf, malformed leaf buds depending on species. Acalitus blastophthirus causes the young leaves to be coated with silver hairs.

Further Reading

Packham et al. 2012. Biological Flora of the British Isles: Fagus sylvatica. Journal of Ecology 100: 1557–1608.


Article created: 14th May 2016; updated: 30 May 2016, 24 May 2021

A beech wood in Autumn.

The beech tree, fungi and tree holes.