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.

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