Alder | Alnus

Alnus cordata, commonly known as the Italian alder, is a medium to large deciduous tree native to southern Italy and parts of Corsica. It belongs to the Betulaceae family and is highly valued for its ability to thrive in poor soils and challenging environmental conditions. This species is often planted for ornamental purposes, soil improvement, and as a windbreak due to its robust growth and adaptability.

The tree can reach heights of up to 25-30 metres (82-98 feet) with a trunk diameter of about 1 metre (3.3 feet). It has a relatively narrow, conical crown, which makes it an attractive choice for landscaping in urban and rural environments. The bark is smooth and greyish-brown when young, developing shallow fissures with age.

Alnus cordata is noted for its distinctive heart-shaped (cordate) leaves, which are bright green and glossy, measuring 7-12 cm in length. Unlike some other alders, the leaves of A. cordata remain on the tree until late autumn, giving it an extended season of greenery. In spring, it produces small, inconspicuous catkins, with male catkins being pendulous and yellowish, and female catkins more compact and upright. These develop into small, woody cones that persist on the tree through winter.

One of the key characteristics of Alnus cordata is its nitrogen-fixing ability. Like other alders, it forms a symbiotic relationship with the bacterium Frankia, which allows it to fix atmospheric nitrogen into the soil. This quality makes it an excellent species for improving soil fertility, particularly in degraded or nutrient-poor areas.

Overall, the Italian alder is a resilient and versatile tree, well-suited to a variety of landscapes, including wet or compacted soils, and is an important species for ecological restoration projects.

Alnus glutinosa, commonly known as the black alder, is a deciduous tree native to Europe, including the British Isles. It is a versatile and resilient species, often found thriving in wetland areas, riverbanks, and marshes, where its roots can help stabilise the soil and prevent erosion.

The black alder typically grows to a height of 20-30 metres, with a broad, conical crown that becomes more rounded with age. Its bark is dark brown and fissured, often developing a distinctive, almost black hue as the tree matures. One of its most notable features is its leaves, which are rounded with a slightly serrated edge and a glossy, dark green surface that turns yellow in the autumn.

In early spring, Alnus glutinosa produces catkins – the male catkins are long and yellowish, while the female ones are shorter and reddish. These mature into woody, cone-like fruits that persist on the tree throughout the winter, providing a valuable food source for wildlife. The black alder also forms symbiotic relationships with nitrogen-fixing bacteria in its root nodules, enriching the soil and benefiting neighbouring plants.

Due to its adaptability and ecological benefits, Alnus glutinosa is often used in reforestation and habitat restoration projects. It supports a wide range of wildlife, including insects, birds, and aquatic species, making it a vital component of the British natural landscape.

Alnus cordata, commonly known as the Italian alder, is a medium to large deciduous tree native to southern Italy and parts of Corsica. It belongs to the Betulaceae family and is highly valued for its ability to thrive in poor soils and challenging environmental conditions. This species is often planted for ornamental purposes, soil improvement, and as a windbreak due to its robust growth and adaptability.

The tree can reach heights of up to 25-30 metres (82-98 feet) with a trunk diameter of about 1 metre (3.3 feet). It has a relatively narrow, conical crown, which makes it an attractive choice for landscaping in urban and rural environments. The bark is smooth and greyish-brown when young, developing shallow fissures with age.

Alnus cordata is noted for its distinctive heart-shaped (cordate) leaves, which are bright green and glossy, measuring 7-12 cm in length. Unlike some other alders, the leaves of A. cordata remain on the tree until late autumn, giving it an extended season of greenery. In spring, it produces small, inconspicuous catkins, with male catkins being pendulous and yellowish, and female catkins more compact and upright. These develop into small, woody cones that persist on the tree through winter.

One of the key characteristics of Alnus cordata is its nitrogen-fixing ability. Like other alders, it forms a symbiotic relationship with the bacterium Frankia, which allows it to fix atmospheric nitrogen into the soil. This quality makes it an excellent species for improving soil fertility, particularly in degraded or nutrient-poor areas.

Overall, the Italian alder is a resilient and versatile tree, well-suited to a variety of landscapes, including wet or compacted soils, and is an important species for ecological restoration projects.

Alnus cordata, commonly known as the Italian alder, is a medium to large deciduous tree native to southern Italy and parts of Corsica. It belongs to the Betulaceae family and is highly valued for its ability to thrive in poor soils and challenging environmental conditions. This species is often planted for ornamental purposes, soil improvement, and as a windbreak due to its robust growth and adaptability.

The tree can reach heights of up to 25-30 metres (82-98 feet) with a trunk diameter of about 1 metre (3.3 feet). It has a relatively narrow, conical crown, which makes it an attractive choice for landscaping in urban and rural environments. The bark is smooth and greyish-brown when young, developing shallow fissures with age.

Alnus cordata is noted for its distinctive heart-shaped (cordate) leaves, which are bright green and glossy, measuring 7-12 cm in length. Unlike some other alders, the leaves of A. cordata remain on the tree until late autumn, giving it an extended season of greenery. In spring, it produces small, inconspicuous catkins, with male catkins being pendulous and yellowish, and female catkins more compact and upright. These develop into small, woody cones that persist on the tree through winter.

One of the key characteristics of Alnus cordata is its nitrogen-fixing ability. Like other alders, it forms a symbiotic relationship with the bacterium Frankia, which allows it to fix atmospheric nitrogen into the soil. This quality makes it an excellent species for improving soil fertility, particularly in degraded or nutrient-poor areas.

Overall, the Italian alder is a resilient and versatile tree, well-suited to a variety of landscapes, including wet or compacted soils, and is an important species for ecological restoration projects.

Alnus glutinosa, commonly known as the black alder, is a deciduous tree native to Europe, including the British Isles. It is a versatile and resilient species, often found thriving in wetland areas, riverbanks, and marshes, where its roots can help stabilise the soil and prevent erosion.

The black alder typically grows to a height of 20-30 metres, with a broad, conical crown that becomes more rounded with age. Its bark is dark brown and fissured, often developing a distinctive, almost black hue as the tree matures. One of its most notable features is its leaves, which are rounded with a slightly serrated edge and a glossy, dark green surface that turns yellow in the autumn.

In early spring, Alnus glutinosa produces catkins – the male catkins are long and yellowish, while the female ones are shorter and reddish. These mature into woody, cone-like fruits that persist on the tree throughout the winter, providing a valuable food source for wildlife. The black alder also forms symbiotic relationships with nitrogen-fixing bacteria in its root nodules, enriching the soil and benefiting neighbouring plants.

Due to its adaptability and ecological benefits, Alnus glutinosa is often used in reforestation and habitat restoration projects. It supports a wide range of wildlife, including insects, birds, and aquatic species, making it a vital component of the British natural landscape.

Alnus glutinosa 'Imperialis,' commonly known as the Imperial Alder, is a cultivar of the European alder (Alnus glutinosa) renowned for its striking ornamental qualities. This deciduous tree is a favoUrite among landscape enthusiasts and horticulturists for its impressive appearance and adaptability.

Imperial Alder typically reaches a height of 40 to 50 feet (12 to 15 meters) and forms a broadly pyramidal shape. Its dark green, glossy leaves are deeply cut and serrated, measuring about 4 to 6 inches (10 to 15 cm) in length. During the growing season, the foliage provides a lush and vibrant backdrop to garden landscapes.

One of the standout features of Alnus glutinosa 'Imperialis' is its stunning catkins. In late winter or early spring, long, pendulous catkins emerge, adding a unique and captivating element to the tree's appearance. These catkins sway gracefully in the wind, creating a charming visual effect. Additionally, this cultivar displays a lovely yellow fall coloUr, which adds to its overall aesthetic appeal.

Imperial Alder is highly adaptable to various soil types and moisture conditions, making it suitable for a wide range of environments. It thrives in full sun to partial shade, making it a versatile choice for gardens and parks. Its ability to tolerate wet soil and even occasional flooding makes it an excellent choice for riparian zones or areas prone to seasonal waterlogging.

Beyond its aesthetic value, Alnus glutinosa 'Imperialis' also contributes to the ecosystem by supporting various wildlife species. Its catkins provide a source of food for birds and insects, and its roots help stabilize soil along riverbanks and wetland areas.

In summary, Alnus glutinosa 'Imperialis' is a captivating cultivar of the European alder celebrated for its striking appearance, adaptability, and ecological contributions. Whether used as a focal point in a garden or to enhance riparian habitats, this tree adds a touch of elegance and functionality to its surroundings.

Alnus glutinosa Laciniata, commonly known as Cut-leaved Alder, is a deciduous tree and a distinct cultivar of the Black Alder. Native to Europe, this ornamental tree is valued for its unique and finely dissected foliage, giving it a delicate and graceful appearance. The deeply lobed, fern-like leaves are dark green, offering a lacy texture that sets it apart from the standard Alnus glutinosa, which typically has more rounded leaves.

Mature trees can reach a height of 12 to 20 metres, with a spread of about 6 to 10 metres, making it a medium-sized tree suitable for gardens, parks, and water-side plantings. The tree has a conical to rounded shape when fully grown, and its branches create an attractive structure, especially in winter when the leaves have fallen.

Like other alders, ‘Laciniata’ is well adapted to wet soils and thrives in damp, poorly drained areas. It is often found near rivers, streams, and wetlands. The tree is also tolerant of urban pollution and can withstand occasional waterlogging, making it a versatile choice for various landscapes.

In spring, ‘Laciniata’ produces small, inconspicuous catkins, which eventually develop into small, woody cones containing seeds. These cones add an extra ornamental feature to the tree, especially in the autumn and winter months.

Alnus glutinosa ‘Laciniata’ is also beneficial to the environment. As a member of the birch family, it has the ability to fix nitrogen in the soil, improving fertility and promoting biodiversity. This makes it an excellent choice for ecological restoration projects.

Overall, Alnus glutinosa ‘Laciniata’ is an elegant and functional tree that brings beauty, wildlife support, and environmental benefits to the landscapes where it is planted.

Alnus incana, commonly known as grey alder, is a deciduous tree belonging to the birch family, Betulaceae. Native to Europe, Asia, and North America, it is a resilient species often found in riparian zones, wetlands, and areas with moist soils. This medium-sized tree typically grows to heights of 15 to 25 metres, with a slender trunk and smooth, greyish-brown bark, which often develops fine fissures with age.

The leaves of Alnus incana are oval to elliptic in shape, measuring 5 to 10 centimetres in length. They are characterised by their serrated margins and a dark green upper surface, with a paler, slightly downy underside, giving them a distinct two-tone appearance. The leaves emerge in early spring and typically turn yellow before falling in autumn.

Grey alder is monoecious, meaning that both male and female reproductive structures are found on the same tree. The male catkins, which are long and pendulous, appear in early spring before the leaves, while the smaller, more upright female catkins develop into woody cones that persist on the tree through the winter. These cones release small winged seeds, which are dispersed by wind and water.

One of the notable features of Alnus incana is its ability to fix nitrogen through a symbiotic relationship with the bacterium *Frankia*. This allows it to thrive in nutrient-poor soils and contribute to soil fertility, making it a valuable species for land restoration and erosion control.

Grey alder is often planted in landscaping and reforestation projects, particularly in areas prone to flooding or soil degradation. Its rapid growth, hardiness, and ecological benefits make it an important species in maintaining the health of wetland ecosystems.

Alnus incana 'Aurea',  known as the Golden Alder, is a deciduous tree prized for its striking yellow foliage and adaptability to various growing conditions. This cultivar is a variation of the grey alder (Alnus incana), native to Europe, North America, and parts of Asia, and is widely cultivated for its ornamental appeal.

Reaching a height of 6 to 10 metres, with a spread of 4 to 6 metres, Alnus incana 'Aurea' is medium-sized, making it suitable for smaller gardens as well as larger landscapes. It is noted for its smooth, greyish bark, which contrasts beautifully with its bright golden-yellow leaves that emerge in early spring. As the season progresses, the foliage turns a lime green, maintaining a light and airy appearance. The leaves are ovate, serrated, and slightly sticky to the touch when young.

In winter, this tree adds visual interest with its small, cone-like fruits and hanging catkins that persist on the branches. The catkins are yellow-brown and appear before the leaves in early spring, contributing to the tree’s year-round appeal.

Alnus incana 'Aurea' is an extremely hardy tree, thriving in a variety of soil types, including wet and poorly drained soils. It is often planted in areas prone to flooding or along riverbanks, as it is highly tolerant of waterlogged conditions. The tree also fixes nitrogen in the soil through symbiotic relationships with root nodules, which improves soil fertility.

Though low-maintenance, the Golden Alder benefits from occasional pruning to maintain its shape and encourage healthy growth. This fast-growing tree is a great choice for those looking to introduce colour and texture to their garden while supporting local wildlife, as it provides shelter and food for birds and insects.

Alnus incana 'Aurea',  known as the Golden Alder, is a deciduous tree prized for its striking yellow foliage and adaptability to various growing conditions. This cultivar is a variation of the grey alder (Alnus incana), native to Europe, North America, and parts of Asia, and is widely cultivated for its ornamental appeal.

Reaching a height of 6 to 10 metres, with a spread of 4 to 6 metres, Alnus incana 'Aurea' is medium-sized, making it suitable for smaller gardens as well as larger landscapes. It is noted for its smooth, greyish bark, which contrasts beautifully with its bright golden-yellow leaves that emerge in early spring. As the season progresses, the foliage turns a lime green, maintaining a light and airy appearance. The leaves are ovate, serrated, and slightly sticky to the touch when young.

In winter, this tree adds visual interest with its small, cone-like fruits and hanging catkins that persist on the branches. The catkins are yellow-brown and appear before the leaves in early spring, contributing to the tree’s year-round appeal.

Alnus incana 'Aurea' is an extremely hardy tree, thriving in a variety of soil types, including wet and poorly drained soils. It is often planted in areas prone to flooding or along riverbanks, as it is highly tolerant of waterlogged conditions. The tree also fixes nitrogen in the soil through symbiotic relationships with root nodules, which improves soil fertility.

Though low-maintenance, the Golden Alder benefits from occasional pruning to maintain its shape and encourage healthy growth. This fast-growing tree is a great choice for those looking to introduce colour and texture to their garden while supporting local wildlife, as it provides shelter and food for birds and insects.

Alnus rubra, commonly known as red alder, is a fast-growing deciduous tree native to the west coast of North America, from Alaska to California. It is easily recognized by its smooth, gray bark and broad, ovate leaves with serrated edges that turn yellow in the fall. Red alder typically grows 40 to 80 feet tall and thrives in moist, well-drained soils, often along rivers, streams, and in disturbed areas. One of its most notable ecological traits is its ability to fix atmospheric nitrogen through a symbiotic relationship with bacteria in its root nodules. This natural enrichment improves soil fertility and supports forest regeneration, making it an important pioneer species in reforestation and ecological restoration projects. Red alder also provides habitat and food for various wildlife species, including birds and insects. In addition to its ecological value, its light-colored wood is used in furniture, cabinetry, and paper production due to its workability and smooth finish.