Manna ash

Family

Oleaceae

Habit

Tree

Height

9.5 m

Spread

6 m

Growth

fast

Lifespan

130 years

First yield

after 6 years

Hardiness

zone 7–9

Shade tolerance

full sun

Soil

Sand, Silt, Loam

Soil moisture

very dry – very moist

pH

6.5 – 8.5

Synonyms

Ornus europaea, Blumen-Esche, Schmuck-Esche

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

Edible: Manna – ein süßes Exsudat wird durch Einschneiden aus den Stämmen gewonnen. Die oberen Stämme haben eine bessere Qualität. Der Geschmack ist mild süß. Hauptsächlich wird es als mildes und schonendes Abführmittel verwendet. Es wird aber auch als Süßungsmittel in zuckerfreien Zubereitungen und als Trennmittel verwendet. Der Baumstamm muss einen Durchmesser von mindestens 8 cm haben, bevor das Manna geerntet werden kann. Im Sommer, wenn der Baum nicht mehr viele neue Blätter bildet, werden mehrere vertikale, schräge Einschnitte in den Stamm gemacht. Von Juli bis Ende September wird täglich ein Schnitt gemacht. Aus diesem Schnitt tritt eine weiße, klebrige Flüssigkeit aus, die aushärtet und dann geerntet wird. Für eine gute Ernte ist trockenes und warmes Wetter unabdingbar. Der Baum wird neun Jahre in Folge abgeerntet, was ihn erschöpft hat. Dieser wird dann abgeschnitten, sodass ein Trieb nachwächst. Es dauert 4 bis 5 Jahre, bis dieser Trieb produktiv wird. Durchschnittliche Erträge von 6 Kilo Manna höchster Qualität pro Hektar sowie 80 Kilo Manna verschiedener Sorten werden erzielt.

Medicinal: The manna extracted from the tree trunk has a gentle laxative and strengthening effect. It is particularly beneficial for children and pregnant women. Its effects are usually very mild but can sometimes cause bloating and pain.

Other uses: Mannitol is of some significance as a sugar substitute for diabetics because it is metabolized independently of insulin. It is also used as a filler and binder for tablets. Mannitol is primarily produced today through the hydrogenation of glucose or invert sugar.

Site: At 5 to 10 metres, rarely 25, the manna ash stays a small to medium tree with a loose, airy crown, making it one of the few ashes that fits an ordinary garden. It is markedly heat-loving, drought-hardy and lime-tolerant and copes with shallow, stony ground where other trees give up; wet, compacted positions, by contrast, are not for it. It is regarded as a promising city and climate tree, not least because it is far less susceptible to ash dieback than common ash. Unlike that species it is insect-pollinated and flowers conspicuously and strongly scented, which makes it a good neighbour for seating areas. The open crown admits enough light for underplanting. Care: Dormant it is hardy, but the young spring flush is frost-sensitive even on older trees; a position that does not thaw in the first morning sun prevents frost damage. Stake for the first few years and let it establish, after which it needs no extra water and should not be watered, since that squanders its drought advantage. Do not fertilise: over-supply makes the wood soft and frost-prone. Prune little and in late summer rather than spring, because it bleeds heavily when the sap is rising; for street trees, raising the crown in the early years is enough. Diseases are rare, with occasional leaf scorch after wet springs.

The manna ash is grown mainly from seed. The winged nutlets ripen in autumn and fall only in winter; they have deep double dormancy, so after ordinary sowing they emerge in the second spring. Two routes shorten this: harvest the fruit green, once it has reached full size but not yet hardened, and sow immediately into an outdoor bed; or give dry seed a warm-then-cold stratification of about two to three months at room temperature followed by three to four months in the refrigerator. Seedlings grow briskly and can be lined out after two years. Cultivars such as the round-crowned 'Mecsek' are grafted onto seedling rootstocks of Fraxinus ornus or Fraxinus excelsior, usually as standards. The species is functionally dioecious, so seed requires several trees within range.

Ecologically the manna ash differs fundamentally from common ash: where that species flowers inconspicuously and is wind-pollinated, the manna ash carries showy, cream-white, strongly scented panicles and is pollinated by insects. From April to June it is therefore a genuine nectar flow, drawing honeybees, hoverflies, beetles and butterflies at a time when the fruit blossom is over. The winged seeds hang on the tree through winter and are prised out by bullfinch, hawfinch and tits when other food runs short. As a southern European neophyte it has no specialised associated fauna in central Europe, but the generalists tied to ash benefit from it, and unlike native ash it rarely falls victim to ash dieback.

Notable: the only ash with scented, insect-pollinated flowers - all the others are inconspicuous+wind-pollinated; manna = dried trunk sap, won by scoring the bark, a craft with its own tools in Sicily for centuries; yield 80-1000kg/ha; name carried over from the biblical manna story; largely resistant to ash dieback.

Mediterranean and western Asia: from Spain through Italy, the Balkans and Turkey to Lebanon and the Caucasus. The manna ash is centred on the eastern Mediterranean and the Balkan peninsula, where it is a defining tree of the dry woodlands. Northwards its natural range reaches the southern edge of the Alps and the submediterranean valleys; in Ticino it climbs to 1165 metres and in South Tyrol to around 1500. It is not native to Germany but persists as a naturalised neophyte in the warm districts of Baden-Württemberg and Franconia, and is increasingly planted as a street and city tree. In southern Italy, particularly Sicily and Calabria, it is grown commercially for manna.

The manna ash is a tree of submediterranean dry woodland and a character species of the Orno-Ostryon alliance, the hop-hornbeam and downy oak forests. It occupies sunny, shallow slopes over limestone and dolomite, rocky crests, karst soils and open scrub: sites far too dry for common ash. Indicator values place it on moderately dry, half-shaded, neutral to basic and rather nutrient-poor ground in warm positions. Its open, airy crown lets plenty of light reach the floor, so a species-rich field layer of dry-grassland plants thrives beneath it. It avoids waterlogging and acidic, lime-free soils.