Sycamore maple

Family

Aceraceae

Habit

Tree

Height

31.5 m

Spread

16 m

Growth

very fast

Lifespan

500 years

First yield

after 20 years

Full yield

after 80 years

Yield in cultivation

up to 12 t/ha

Energy yield

75 kcal per m² a year

Hardiness

zone 5–7

Shade tolerance

partial shade

Soil

Sand, Silt, Loam, Clay

Soil moisture

semi-dry – very moist

pH

5 – 8

Synonyms

Bergahorn

Times apply to the northern hemisphere in a temperate climate and shift with altitude and cultivar.

Edible: What is used is essentially the spring sap. Before the leaves break, usually between February and early April, the tree stands under root pressure; drill the trunk and a clear, faintly sweet sap runs, drunk fresh or boiled down to syrup as with sugar maple. The sugar content is well below that of Acer saccharum, so a great deal must be evaporated for one litre of syrup. Seal the tap holes after harvest, and only tap strong, healthy trunks. The leaves were formerly used as wrapping to keep bread dough, butter and cheese fresh. Seeds and seedlings are emphatically not food: they contain hypoglycin A, the same substance that causes severe poisoning in grazing animals.

Medicinal: No medicinal use of sycamore maple is documented. Tradition records that maple leaves were applied externally as a poultice on wounds in folk medicine and that the spring sap was regarded in the Alps as a strengthening spring drink — both historically attested, without evidence of efficacy.

Other uses: Sycamore timber ranks among the fine hardwoods: pale to almost white, fine-pored, even and odourless. It goes into furniture, parquet, staircases and turnery, and because it gives off no smell of its own, traditionally into kitchen utensils, dough troughs and butchers' blocks. Trunks with wavy grain — fiddleback sycamore — are the classic wood for the backs and ribs of violins and guitars and fetch top prices. In the Alps sycamores were left standing as pasture trees on the high meadows, where they give shade and shelter to stock; individual trees are several hundred years old. The foliage was pollarded for winter fodder, and the leaves served as wrapping and lining material in food storage.

Site: Sycamore maple reaches 25 to 30 metres and almost the same in width with age — a tree for large grounds, pasture and avenues, not for the home garden. What matters most is distance from horse pasture and small-livestock runs: the seeds and seedlings contain hypoglycin A and cause atypical myopathy in horses, which is usually fatal. The winged fruits travel far, so a buffer of at least fifty metres to grazing land is sensible. Self-seeding is heavy; the following year seedlings stand in beds, paving joints and hedges. As a heart-rooter it occupies the soil deeply and makes underplanting laborious, and the coarse leaf litter breaks down slowly and does not belong in ponds. For bees it is one of the richest nectar sources of May. Care: Young trees need a three-stake support for three to four years plus protection against deer browsing and hares gnawing the bark. Prune in summer or late summer — in late winter and early spring the tree bleeds heavily from every cut. Do not feed it; it already benefits from airborne nitrogen. Tar spot draws black blotches on the leaves in late summer and is purely cosmetic. What does matter is verticillium wilt, for which no treatment exists, and sooty bark disease, which follows drought years: its spores can trigger allergic alveolitis in humans, so affected trees must be felled damp and with respiratory protection.

Sycamore maple all but propagates itself — natural regeneration is abundant, and anyone needing young plants simply lifts seedlings in spring. For deliberate raising, collect the winged fruits in September and October and sow them at once outdoors or in seed trays left outside over winter; the seed needs cold to germinate and comes up the following spring. Badly dried seed loses viability fast; if it must be stored, give it two to four months of stratification at one to five degrees before sowing. Protect seedbeds from mice. Cuttings root poorly, so named cultivars are whip-grafted onto seedling rootstocks in winter or budded in summer. Trees cut to the stump resprout reliably, which makes pollarding and coppice management possible.

Sycamore maple is one of the most productive nectar sources of spring. Its inconspicuous greenish flowers open in May together with the leaves and yield nectar and pollen in quantity; honeybees, mining and mason bees, hoverflies and beetles work them, and pollination is by insects with wind as a supplement. Moth caterpillars, longhorn beetles and gall mites live on the leaves, wood and bark — the red pustules the mites raise on the foliage are harmless. Old trees with cavities and coarse bark are breeding and hunting ground for woodpeckers, nuthatches and bats, while bullfinches, hawfinches and mice take the winged fruits. In Central Europe the sycamore is native and a load-bearing species of its mountain forests; outside Europe, in New Zealand for instance, it counts as invasive.

Special features: Super chop & drop mulch & soil builder; syrup min. 60% sugar; sugar maple (Acer saccharum) needs a more continental climate, grows slowly, is 3x richer in sugar, has more culinary and medicinal uses; field maple (Acer campestre) leaves + leaf stalks + sauerkraut; sycamore is popular as a deer grazing material, but poisonous to horses;

Europe and western Asia. The continuous range runs from the Pyrenees across the Alps, the Apennines and the Carpathians to the Caucasus and Asia Minor; in Central Europe it is the commonest maple of the mountains. Its centre of distribution lies between 900 and 1,300 metres, reaching about 850 m in the Harz, 1,300 m in the Bavarian Forest, 1,400 m in the Black Forest and over 1,600 m in the Alps. North of the low mountain ranges it occurs naturally only on the more base-rich glacial soils of the plain; elsewhere it is largely planted and naturalised from plantings. Introduced as a forestry and park tree to North America, New Zealand, Australia and Argentina, where it spreads invasively in places.

Sycamore maple is a tree of cool, moist mountain country with a humid, sub-Atlantic climate. Its strongholds are ravine forests shared with ash and wych elm, goatsbeard-sycamore woodland, high-montane sycamore-beech forest and subalpine spruce-fir forest; it also appears in carbonate spruce-fir-beech and oak-ash woodland. It demands soils that stay fresh, well supplied with nutrients and rich in bases — limestone slope scree, loess loam, weathered basalt, mild clays — and coarse block scree is a characteristic special habitat. It avoids strongly alternating wet-dry ground, very acid and dry sites, base-poor groundwater soils, glacial sands and the more strongly pseudogleyed soils of the uplands. High airborne nitrogen inputs favour it, so it is currently expanding onto sites where it was formerly absent.