American maple, a common name for acer negundo, is native to North America, from where it was imported into Europe starting in the eighteenth century. The name maple has a Latin etymology: it derives from the adjective "acer" which means sour, hard. On the other hand, the etymology of negundo is uncertain. According to some interpretations it derives from "negus", with the meaning of Indian.
The acer negundo belongs to the aceraceae family and is classified as a deciduous tree. Its growth is very fast, but its age is short. It reaches heights ranging from ten to twenty meters and has a decidedly dense crown of leaves that appear to be arranged in a disorderly manner.
The leaves are pinnate and have a length ranging from 15 to 30 centimeters. They are composed of three to five oval leaflets, which have toothed margins, light green in color and an ovoid-elliptical shape. Not infrequently you can admire ornamental maple species with mottled yellow or white leaflets.
The maple has dioecious flowers, very inconspicuous, which appear before the leaves and are greenish in color. The male ones are gathered in erect inflorescences, while the female ones are gathered in pendulous racemes.
Its fruits are samaras that appear with divergent, slightly curved wings, have a brown color and persist on the tree even after the leaves have fallen.
Acer negundo has a shrubby development, is an ornamental and rustic tree, usually grown along roads and avenues and often occurs near waterways. Cultivation often occurs in isolation and is usually done to shade or create a shelter from the wind.
Cultivation in pots is limited to acer japonicum, through a technique that involves the use of particular boxes that have 70 centimeters on each side and seventy centimeters in depth: the soil that houses the plant must then always be fresh: it is therefore recommended water with a bucket of water a day in the hottest seasons, decreasing the water doses as temperatures cool down.
Acer negundo wants exposure to the sun that lasts a few hours a day. His preference is definitely for moist soils, with excellent drainage, even better if clayey: cultivation must be carried out in a soil mixed with a tenth of river sand in order to facilitate the drainage of rainwater. The plant also resists climatic variations very well, much less drought and strong wind.
To improve the fertility of the soil and help the growth of the maple, it is possible to carry out two types of cultivation: it is very advisable to pour a bucket of water regularly once or twice a year, enriched with thirty grams of complete mineral fertilizer dissolved in liquid.
As for the maples grown in pots, their preference goes to a fertilization with organic fertilizer in powder that must be spread on the damp earth, freed of its surface layer, to be carried out regularly in the autumn season and at the end of winter. Ammonium sulphate, on the other hand, is recommended for the month of April, in order to help the development of the leaves.
Also with regard to watering, there are two types recommended for a correct cultivation of the plant. For those that grow in full soil, watering is only needed for the first years of their life. Later, in fact, their roots are able to reach deep layers with the right degree of humidity to guarantee their survival.
For those plants instead that see their cultivation in pots, in the special boxes seventy by seventy cm, as mentioned, watering is necessary that guarantees the humidity of the soil: a bucket of water a day in concomitance with the seasons. warmer, less as the temperature cools.
Propagation occurs in three ways: by seed, by grafting and by cuttings.
In order to prevent problems related to the attack of parasites, it is very advisable to use a broad-spectrum insecticide in the spring season, with a systemic fungicide, to combat the potential unwelcome arrival of aphids or fungal diseases, which often occur in the presence of a cool and humid climate.
There are three different species of negundo. The acer negundo with a silvery-marginatum variation, which boasts white-edged leaves; acer negundo with a gold-marginatum variation with yellow-edged leaves. Finally, acer californicum, a subspecies of the Negundo, much more favorable to cultivate in the presence of dry soils.
Used as an ornamental tree, to embellish avenues, roads or to offer a natural shelter from the wind, acer negundo does not find widespread use in carpentry, due to its fragile and light wood, which can however be used for fiber products. wood. Its sap is not so sugary as to be used for the production of maple syrup, for which other species are much preferred.
Maple it is one of the most common trees in parks and gardens throughout most of the world, due to the grace of its posture but above all for its characteristic decorative foliage, with its typical webbed shape and bright color. It's a deciduous broad-leaved trees, prefers the temperate weather and is grown mainly as ornamental plant.
The genus Acer belongs to the family of Aceraceae, which includes about 200 species. Native to North America, Europe and East Asia, this family includes are small shrubs of about one meter either large trees that exceed 40 meters in height.
The flowers are small, gathered in yellow or green clusters, while the palmate leaves they vary greatly depending on the species, being simple or compound and counting from 3 to 7 oblong or lanceolate lobes.
There Acer negundo is a tree belonging to the Sapindaceae family. It is also referred to by the common name of American Maple. It has a very high height of over 12 meters and is well suited to large gardens. while the width is greater than 9 meters. It takes an average of 10-20 years to reach its maximum development. The species is characterized by deciduous foliage. Cultivation can be done in: informal garden, gravel garden, Mediterranean garden, pot or container, architectural garden, terrace or yard, rock garden.
About 160 species of trees and shrubs distributed in the temperate regions of Europe, Asia and North America form the genus Acer , of the family Sapindaceae . Some species of this genus are: Acer obtusifolium, Acer campestre, Acer sempervirens, Acer negundo, Acer platanoides, Acer pseudoplatanus, Acer palmatum.
It receives the common names Syrian Maple or Oriental Maple and the scientific synonyms Acer oriental and Acer syriacum. It is a species native to the eastern part of the Mediterranean basin.
They are shrubs or small trees with a smooth bark and a somewhat pyramidal shape that generally do not exceed 8 meters in height. It has leaves hard , bright green and trilobate (trilobate). The flowers are greenish-yellow, but are not of ornamental interest. They bloom at the end of winter. The fruits are small chambers about 2 cm long.
Although their use is not widespread , can be used as isolated examples or to form informal screens and hedges.
The Syrian maple prefers full sun exposure and it is resistant to intense heat and frost, although if it is persistent it can lose its leaves and regrow in late winter.
They are not at all demanding with the terrain and they can thrive in all places except salt flats.
They are resistant to drought and will then be watered fairly moderately until the soil dries up.
Only pruning to remove old or damaged branches at the end of winter, when the danger of frost has passed.
Even if the fertilizer it is not strictly necessary, organic matter can be added in autumn.
I'm resistant to typical garden pests, but they can be attacked by fungi if there is an excess of humidity.
You can easily multiply from seeds sown in spring.
In Padua Curly maple, Acer platanoides, it means Prato della Valle. Actually it has not always been like this, until the end of the eighties huge plane trees lived there, then felled because attacked by a mushroom that killed them all.
The curly maples of the Prato in May. In the background the Basilica of Santa Giustina. The statues that adorn the square, the maple trees and the characteristic domes of the Saint Among the plants, just darkened in early October, Palazzo Angeli, seat of the Precinema Museum. The Amulea Loggia which houses the Paduan section of the Dante Alighieri Society. Christmas decorations.
The curly maple takes its common name from the showy cusps of the leaf and the leaf, which recalls, especially near the petiole, that of the plane tree, inspires the scientific name, Acer platanoides.
Deep green leaf, lighter veins and petiole. Above left, the winged seed. Light brick hair in the armpits of the veins Perlasca Park. The characteristic leaves with the canonical five lobes and sharp teeth. As often happens, the names of the species refer to each other, here the leaf of Platanus acerifolia. And in order not to miss anything, there is also the Acer pseudoplatanus.
All maples have similar fruits: a pair of winged seeds, samaras. It is not easy to distinguish them, but the angle formed by the samaras can help.
In the case of the curly maple, the two winged seeds are almost aligned
Acer platanoides it is a tree of medium height and grows rather slowly, the foliage is often expanded irregularly, and it is beautiful to admire especially in March-April when it blooms before putting out the leaves.
A short row of splendid curly maples in the Riviera San Benedetto in full bloom. The photo is from the end of March The short row seen from the Ponte dei Tadi Here in November Still Prato della Valle Two young curly maples in Piazza Delia, in the foreground a Tilia cordata. The photo is taken in May, note the bracts, of the lime tree, and the samaras, of the maple, which dot the dark foliage of the two plants with their light colors. A young curly maple at the Ognissanti Park in Via Fistomba Parco Ognissanti in December, in the foreground a curly maple A group of very yellow curly maples at the Iris Park, here these plants live numerous. November at the Perlasca Park Flowering curly maple in Prato della Valle The greenish-yellow flowers are grouped in bunches (corymbs) Pentagonal symmetry flower. The same plant bears both male and hermaphrodite flowers. In the photo on the right you can see the stigma that forks, and below, between the turgid stamens, the ovary. While in the photo on the left you can see the lack of the pistil, the female organ. With the sprouting of the leaves the fertilized flowers begin to show the samaras and the corymbs prostrate. Ellipsoidal capsules enclose the flowers Red-brown gem: peculiar character. The smooth bark in trees or young branches cracks with age in long furrows that in older plants seem to intertwine with each other. An elderly specimen at Parco Treves with the typical "snake skin" bark.
The species has numerous varieties, particularly beautiful ones with variously colored leaves. But this will be the subject of a new post.
Indicative of its familiarity to many people over a large geographic range, A. negundo has numerous common names. The names "box elder" and "boxelder maple" are based upon the similarity of its whitish wood to that of boxwood and the similarity of its pinnately compound leaves to those of some species of elder. 
Other common names are based upon this maple's similarity to ash, its preferred environment, its sugary sap, a description of its leaves, its binomial name, and so on. These names include "Manitoba maple", "ash-leaf maple", "cut-leaved maple", "three-leaf maple", "ash maple", "sugar maple", "negundo maple", and "river maple". 
Names vary regionally. Box elder, boxelder maple, ash-leaved maple, and maple ash are among its common names in the United States. In Canada it is commonly known as Manitoba maple and occasionally as elf maple.  in the British Isles it is known as box elder  or ashleaf maple.  In Russia it is known as American maple (Russian: американский клён, tr. amerikansky klyon) as well as ash-leaf maple (Russian: клён ясенелиястный, tr. klyon yasenelistny).
Acer negundo is a fast-growing and fairly short-lived tree that grows up to 10–25 m (35–80 ft) tall, with a trunk diameter of 30–50 cm (12–20 in)>, rarely up to 1 m ( 3.3 ft)> diameter. It often has several trunks and can form impenetrable thickets.  The typical lifespan of box elder is only 60 years. Under exceptionally favorable conditions, it may live to 100 years. [ citation needed ]
The shoots are green, often with a whitish to pink or violet waxy coating when young. Branches are smooth, somewhat brittle, and tend to retain a fresh green color rather than forming a bark of dead, protective tissue. The bark on its trunks is pale gray or light brown, deeply cleft into broad ridges, and scaly. 
Unlike most other maples (which usually have simple, palmately lobed leaves), Acer negundo has pinnately compound leaves that usually have three to seven leaflets. Simple leaves are also occasionally present technically, these are single-leaflet compound leaves. Although some other maples (such as Acer griseum, Acer mandshuricum and the closely related A. cissifolium) have trifoliate leaves, only A. negundo regularly displays more than three leaflets. The leaflets are about 5–10 cm (2–4 in)> long and 3–7 cm (1 1 ⁄4 – 2 3 ⁄4 in)> wide with slightly serrate margins. Leaves have a translucent light green color and turn yellow in the fall.
The yellow-green flowers are small and appear in early spring, with staminate flowers in clusters on slender pedicels and pistillate flowers on drooping racemes 10–20 cm (4–8 in)> long.
The fruits are paired samaras on drooping racemes, each seed slender, 1–2 cm (1 ⁄2 – 3 ⁄4 in)> long, with a 2–3 cm (3 ⁄4 – 1 1 ⁄4 in)> incurved wing they drop in autumn or they may persist through winter. Seeds are usually both prolific and fertile. 
Unlike most other maples, A. negundo is fully dioecious and both a male and female tree are needed for reproduction to occur.
(taken from "Maples, October Fire", by L. Ferrari, no. 10-2010)