Alders are trees of the genus Alnus in the birch family Betulaceae. The genus includes about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few species extending into Central America, as well as the northern and southern Andes.
Alnus glutinosa, the common alder, black alder, European alder, European black alder, or just alder, is a species of tree in the family Betulaceae, native to most of Europe, southwest Asia and northern Africa. It thrives in wet locations where its association with the bacterium Frankia alni enables it to grow in poor quality soils. It is a medium-sized, short-lived tree growing to a height of up to 30 metres (98 feet). It has short-stalked rounded leaves and separate male and female flowers in the form of catkins. The small, rounded fruits are cone-like and the seeds are dispersed by wind and water.
Alnus rubra, the red alder, is a deciduous broadleaf tree native to western North America.
Alnus incana, the grey alder, tag alder or speckled alder, is a species of multi-stemmed, shrubby tree in the birch family, with a wide range across the cooler parts of the Northern Hemisphere. Tolerant of wetter soils, it can slowly spread with runners and is a common sight in swamps and wetlands.
Alnus jorullensis, commonly known as Mexican alder, is an evergreen or semi-evergreen alder, native to eastern and southern Mexico, Guatemala, and Honduras. Although previously reported from the Andes, further collections showed these to be the similar species A. acuminata, commonly found in South America.
Betula papyrifera is a short-lived species of birch native to northern North America. Paper birch is named after the tree's thin white bark, which often peels in paper-like layers from the trunk. Paper birch is often one of the first species to colonize a burned area within the northern latitudes, and is an important species for moose browsing. Primary commercial uses for paper birch wood are as boltwood and sawlogs, while secondary products include firewood and pulpwood. It is the provincial tree of Saskatchewan and the state tree of New Hampshire.
Alnus cordata, the Italian alder, is a tree or shrub species belonging to the family Betulaceae, and native to the southern Apennine Mountains and the north-eastern mountains of Corsica. It has been introduced in Sicily, Sardinia, and more recently in Central-Northern Italy, other European countries and extra-European countries, where it has become naturalised.
Ziziphus mauritiana, also known as Indian jujube, Indian plum, Chinese date, Chinee apple, ber and dunks is a tropical fruit tree species belonging to the family Rhamnaceae. It is often confused with the closely related Chinese jujube, but whereas Z. jujuba prefers temperate climates, Z. mauritiana is tropical to subtropical.
Fraxinus latifolia, the Oregon ash, is a member of the ash genus Fraxinus, native to western North America.
Prosopis pallida is a species of mesquite tree. It has the common names kiawe, huarango and American carob, as well as "bayahonda", "algarrobo pálido", and "algarrobo blanco". It is a thorny legume, native to Colombia, Ecuador and Peru, particularly drier areas near the coast. While threatened in its native habitat, it is considered an invasive species in many other places.
Alnus rhombifolia, the white alder, is an alder tree native to western North America, from British Columbia and Washington east to western Montana, southeast to the Sierra Nevada, and south through the Peninsular Ranges and Colorado Desert oases in Southern California. It occurs in riparian zone habitats at an altitudes range of 100–2,400 metres (330–7,870 ft). While not reported in northern Baja California, it has been predicted on the basis of its climatic adaptation to occur there also. Alnus rhombifolia is primarily found in the chaparral and woodlands, montane, and temperate forests ecoregions.
Alnus acuminata is a species of deciduous tree in the Betulaceae family. It is found in montane forests from central Mexico to Argentina.
Frangula alnus, commonly known as alder buckthorn, glossy buckthorn, or breaking buckthorn, is a tall deciduous shrub in the family Rhamnaceae. Unlike other "buckthorns", alder buckthorn does not have thorns. It is native to Europe, northernmost Africa, and western Asia, from Ireland and Great Britain north to the 68th parallel in Scandinavia, east to central Siberia and Xinjiang in western China, and south to northern Morocco, Turkey, and the Alborz in Iran and the Caucasus Mountains; in the northwest of its range, it is rare and scattered. It is also introduced and naturalised in eastern North America.
Betula utilis, the Himalayan birch, is a deciduous tree native to the Western Himalayas, growing at elevations up to 4,500 m (14,800 ft). The Latin specific epithet utilis means "useful", and refers to the many uses of the different parts of the tree. The white, paper-like bark was used in ancient times as a writing surface for manuscripts of Sanskrit literature. It is still used as paper for the writing of mantras, with the bark placed in an amulet and worn for protection. Selected varieties are used for landscaping throughout the world, even while some areas of its native habitat are being lost due to overuse of the tree for firewood.
Rubus nepalensis, the Himalayan creeping bramble or Nepalese raspberry, is a species of evergreen raspberry endemic to Nepal and Himalayan India. It grows to about 1m in diameter, with height up to 20 cm. The fruit is small, edible, and slightly sour.
Alnus serrulata, the hazel alder or smooth alder, is a thicket-forming shrub in the family Betulaceae. It is native to eastern North America and can be found from western Nova Scotia and southern New Brunswick south to Florida and Texas.
Populus ciliata, the Himalayan poplar, is a large deciduous tree with tall clean straight trunk and wide rounded crown. The bark of the young trees is smooth and greenish-grey while the bark of the old trees is dark brown with vertical cracks. Leaves are broadly ovate with hairy serrulate-crenate margins. Flowers are drooping raceme catkins that appear before or with leaves. Populus ciliata flowers are dioecious. Male flowers have a bell-shaped perianth and female flowers are bluntly toothed. A single capsule encloses an average of 100–150 seeds, which are covered by long silky hair.
Alnus alnobetula is a common tree widespread across much of Europe, Asia, and North America. Many sources refer to it as Alnus viridis, the green alder, but botanically this is considered an illegitimate name synonymous with Alnus alnobetula subsp. fruticosa.
Drypetes gerrardii is a species of small tree or large shrub in the family Putranjivaceae. Common names include forest ironplum, bastard white ironwood, and forest ironwood. It is native to tropical and subtropical central and eastern Africa. It was first described in 1920 by the English botanist John Hutchinson, who named it after the English botanist William Tyrer Gerrard who collected plants and seeds in southern Africa in the 1860s.
Alnus nitida, the west Himalayan alder, is a species in the genus Alnus, native to Pakistan, the western Himalayas, and Nepal. It is a tree reaching 20 to 25 m, preferring to live along the banks of rivers. It is used locally for timber and firewood, and as a street tree. The bark is used in some places for tanning and dyeing purposes. It grows well in heavy, clay soils and tolerates infertile soils. The leaves are thin, oval to ovate, 3-6 inches long and 2-3 inches wide. Female flowers appear first, followed by male catkinss in September to October, which may be up to 19 cm long. The fruits are woody cones, typically 2.5-3.5 cm long.
