Alnus comprises robust deciduous trees and sizable shrubs characterized by their rounded foliage and, during winter, noticeable catkins.

Alnus

Alnus acuminata

Alnus acuminata subsp. acuminata

Alnus acuminata subsp. arguta

Alnus acuminata subsp. glabrata

Alnus aff. jorullensis

Alnus alnobetula

Alnus alnobetula subsp. crispa

Alnus alnobetula subsp. crispa var. mollis

Alnus alnobetula subsp. fruticosa

Alnus alnobetula subsp. sinuata

Alnus alnobetula subsp. suaveolens

Alnus cordata 'Catkins'

Alnus cordata (Loisel.) Duby is a robust deciduous tree that reaches a medium height, characterized by its glossy, dark green foliage. The male catkins are yellow and can grow up to 10 cm long. Its fruit measures approximately 2.5 cm and has a cone-shaped appearance.

Alnus cordata (Loisel.) Duby

Alnus cordata subsp. cordata

Alnus cordata subsp. neapolitana is a rapidly growing deciduous tree, reaching heights of approximately 15 meters when provided with optimal conditions. It features heart-shaped leaves that are dark green and glossy on the upper surface, with branches exhibiting a horizontal growth habit. The foliage persists into autumn, maintaining its green coloration for an extended period. In spring, both male and female trees produce yellow catkins, which are followed by clusters of greenish-brown fruits resembling pineapples. During winter, small, winged seeds are released. This tree serves effectively as a windbreak and can be used as a screen in expansive landscapes.

Alnus cordata subsp. neapolitana

Alnus cremastogyne is a rapidly growing deciduous tree that can reach heights of up to 40 meters. Its leaves are substantial, measuring as much as 15 centimeters in length, and are robust and green, attached to elongated petioles. The female flowers appear as solitary green cylinders that dangle from the branches. In the fall, the tree does not display any color change; instead, the leaves fall while remaining green.

Alnus cremastogyne

Alnus fauriei

Alnus fauriei from Niigata, Japan

Alnus ferdinandi-coburgii is a deciduous tree that can reach heights of up to 20 meters. Its robust green foliage is characterized by a fine layer of yellow hairs. Unlike many deciduous species, this tree's leaves do not exhibit autumn coloration; they simply fall while still green. Male catkins emerge in the autumn, gradually enlarging before fully opening in late spring. The female structures develop on solitary stems, maturing into round, woody fruits that persist on the tree throughout the winter months.

Alnus ferdinandi-coburgii

Alnus firma

Alnus firma var. hirtella

Alnus formosana is a rapid-growing, deciduous tree that reaches heights of up to 20 meters. Its leaves are elongated and start off pink before maturing to a glossy green, ultimately dropping in autumn. In the spring, numerous male catkins appear, while the female woody cones remain attached to the branches throughout the winter months.

Alnus formosana

Alnus glutinosa is a deciduous tree that can reach heights of up to 25 meters. In its early stages, it has a broadly conical shape. During winter, its grey-purple buds and young catkins become prominent features. The leaves are rounded and a vibrant green as they mature.

Alnus glutinosa

Alnus glutinosa 'Aurea'

Alnus glutinosa 'Folly Bottom Sunshine'

Alnus glutinosa 'Imperialis' is a medium-sized tree with a conical shape and graceful growth pattern. Its leaves are deeply lobed and pinnate. The tree produces purplish male catkins and small, cone-shaped fruits.

Alnus glutinosa 'Imperialis'

Alnus glutinosa 'Laciniata' is a sizable, typically multi-stemmed tree commonly found near riverbanks. Its leaves are thick and green, featuring pronounced indentations between the veins that create narrow lobes. The foliage remains green through the fall without any significant autumn coloration. In winter, the tree showcases upright catkins that are deep red, adding a subtle vibrancy to the landscape. Female flowers emerge as small clusters that mature into durable, woody cones.

Alnus glutinosa 'Laciniata'

Alnus glutinosa 'Pyramidalis'

Alnus glutinosa 'Razzmatazz' (v)

Alnus glutinosa f. incisa

Alnus glutinosa from Corsica

Alnus glutinosa subsp. betuloides

Alnus glutinosa var. barbata

Alnus henryi is a rapidly growing deciduous tree that can reach heights of up to 20 meters. Its leaves are elongated, initially pink, and transition to a glossy green as they mature, before dropping in the autumn. In late summer, numerous male catkins appear, while the female cones remain attached to the branches in clusters throughout the winter months.

Alnus henryi

Alnus hirsuta

Alnus hirsuta var. mandschurica

Alnus hirsuta var. sibirica

Alnus imperialis asplenifolia

Alnus incana is a conical tree that can reach heights of up to 20 meters. Its dark green leaves can grow to 10 centimeters in length, featuring a grey-white, hairy underside. In late winter or early spring, before the foliage emerges, the tree produces yellow-brown male catkins that hang in clusters of three or four. The ovoid fruit appears during the summer months.

Alnus incana

Alnus incana 'Angustissima' is a medium-sized deciduous tree that can reach heights of up to 20 meters. Its leaves are finely structured, with much of the leaf area reduced around the veins, resulting in a lacy appearance that provides less shade than typical foliage. In autumn, the leaves turn a light yellow before dropping. During late winter, the male catkins, which are purple-brown, emerge and can grow up to 8 centimeters long, while the female cones form clusters and remain on the tree throughout the winter months.

Alnus incana 'Angustissima'

Alnus incana 'Aurea' is a sizable, conical deciduous tree characterized by its yellow-green foliage. In spring, it produces prominent male catkins that can reach lengths of up to 10 cm. The smaller female catkins develop into small, cone-shaped fruits that mature to a dark brown hue in autumn and remain on the tree throughout the winter months.

Alnus incana 'Aurea'

Alnus incana 'Johanna'

Alnus incana 'Laciniata'

Alnus incana 'Pendula'

Alnus incana 'Pinnatipartita'

Alnus incana 'Ramulis Coccineis'

Alnus incana f. montrosa

Alnus incana subsp. incana

Alnus incana subsp. rugosa

Alnus incana subsp. tenuifolia

Alnus inokumae is a rapidly growing deciduous tree that can reach heights of up to 30 meters. Its leaves measure approximately 8 centimeters in length and exhibit an oval form, featuring a green upper surface and a downy cream underside before they drop in autumn. In late winter, the tree produces male catkins, which cluster together and measure around 8 centimeters. The female cones, which are woody, remain attached to the branches throughout the winter months.

Alnus inokumae

Alnus japonica

Alnus japonica var. arguta

A nearly evergreen tree that reaches heights of up to 25 meters, this species maintains its foliage throughout the winter months, shedding leaves in spring to quickly grow new ones. The leaves display a vibrant green hue, characterized by widely spaced serrations and an elongated shape. In spring, male catkins appear in a creamy color, while female woody cones develop by autumn. This tree can be pruned into a hedge and is suitable for pleaching, allowing for a distinct trunk.

Alnus jorullensis

Alnus kamtschatica

Alnus lanata

Alnus maritima

Alnus maritima subsp. maritima

Alnus maritima subsp. metoporina

Alnus maritima var. obtusata

Alnus matsumurae

Alnus maximowiczii

Alnus maximowiczii from Ulleungdo, South Korea

Alnus nepalensis is a rapidly growing deciduous tree that can reach heights of up to 30 meters. Its leaves are a deep green on the upper side and lighter underneath, measuring around 18 centimeters in length, and they do not change color in the fall. In autumn, long cream-colored male catkins appear, hanging in large clusters. The female cones, which are woody, form later and are positioned upright in clusters on the bare branches.

Alnus nepalensis

Alnus nipponica

Alnus nitida

Alnus oblongifolia

Alnus orientalis

Alnus orientalis var. orientalis TURX 94

A small, multi-stemmed tree or shrub, Alnus pendula typically reaches heights of up to 8 meters and spreads about 5 meters wide. Its branches exhibit a weeping habit, creating a distinctive silhouette. The leaves are robust, glossy green, and may occasionally reveal their lighter, fuzzy undersides. In spring, male catkins emerge, followed in autumn by the development of woody female cones.

Alnus pendula

Alnus relatus

Alnus rhombifolia

Alnus rubra is a medium-sized, fast-growing tree that can reach heights of approximately 19 meters. It features a narrow, pyramidal crown with branches that tend to droop. The leaves are large and lobed, displaying a dark green color on the upper side and a greyish hue underneath. Male catkins can grow up to 15 centimeters in length, while the tree's fruits are barrel-shaped and measure around 1.5 centimeters long.

Alnus rubra

Alnus rubra f. pinnatisecta

Alnus serrulata is a deciduous shrub that often grows in a multi-stemmed form, capable of creating dense thickets. Its leaves are thick and green, lacking any notable autumn coloration and remaining on the plant until they turn green before dropping. In winter, the upright catkins develop a deep red hue, adding visual interest. The small female flowers mature into clusters that form durable wooden cones.

Alnus serrulata

Alnus serrulata 'Panbowl'

Alnus sieboldiana is a medium-sized deciduous tree or shrub that typically reaches heights of up to 12 meters. Its foliage consists of green leaves with lighter undersides, featuring serrated margins and prominent veins. The male catkins are robust and yellow, while the female reproductive structures resemble woody cones, measuring 2-3 centimeters in length, and are found individually during the autumn and winter months.

Alnus sieboldiana

Alnus spectabilis

Alnus subcordata is a rapidly growing, medium-sized tree characterized by its conical form. It features glossy, broadly heart-shaped leaves that are mid-green and have serrated margins. The bark is brown-grey and fissured, offering visual interest throughout the year. This species produces elongated male catkins that hang down, as well as shorter, upright female catkins, which are succeeded by woody fruit. It can thrive in poor or waterlogged soils.

Alnus subcordata

Alnus trabeculosa

Alnus ullungdoensis is a sizable, rapidly growing tree that can reach heights of up to 15 meters. It features large, oval leaves with long serrations, displaying a vivid green color. During the transition from winter to spring, it produces numerous yellow catkins, which can grow as long as 10 centimeters.

Alnus ullungdoensis

Alnus x aschersoniana

Alnus x elliptica

Alnus x hybrida

Alnus x koehnei

Alnus x pubescens var. americana

Alnus x purpusii

Alnus x silesiaca

Alnus x spaethii is a robust, rapidly growing tree that typically reaches heights exceeding 12 meters. It has a conical shape and produces large, elongated leaves with serrated edges, which exhibit a purplish tint during their early development. In spring, the tree showcases clusters of yellow catkins. This species is well-suited for expansive areas or urban streetscapes.