Recognize alder leaf: 14 characteristics to identify

Alders are deciduous, deciduous trees or shrubs. Three species are native to Central Europe. Other alder species are more or less widespread. The typical alder leaf cannot be described as there are hardly any similarities.

Erlen

The plant genus alder (Alnus) belongs to the birch family (Betulaceae). There are about 41 species. Of these, those in Central Europe are

  • Gray alder (white alder, bot. Alnus incana)
  • Green alder (Alpine alder, bot. Alnus alnobetula)
  • Black Alder (Red Alder, Alnus glutinosa)

native. The following alder species can also be found in gardens, parks or on streets:

  • Cordate alder (Italian alder, bot. Alnus cordata)
  • Rot-Erle (Oregon-Erle, bot. Alnus rubra)
  • Purple alder (Large-leaved alder, bot. Alnus x spaethii)
  • Alnus company (rare)
  • Oriental alder (Turkish alder, bot. Alnus orientalis, rare)
  • Wrinkled Alder (Alnus incana subsp. rugosa)

In Brandenburg, a cross between wrinkled alder and black alder was found (Alnus glutinosa × Alnus rugosa or Alnus × silesiaca).

Alder leaf characteristics

There are no typical features that help to identify the alder leaf, because the leaves of the individual species often only differ in one feature from (all) other species.

native alders

Gray alder (species)

  • Arrangement: alternate
  • Leaf color: dark green (upper side), grey-green underside
  • leaf-blade: ovate to elliptic
  • Length: 4 to 10 centimeters
  • Width: 3 to 7 centimeters
  • Leaf base (blade base): rounded to slightly heart-shaped
  • Leaf margin: roughly doubly serrate
  • Leaf tip: acuminate
  • 8 to 12 pairs of nerves
  • petiole: two to three centimeters
  • Autumn colour: none to brownish
  • young leaves: grey-tomentose hairy underside
Note: The size and shape of the leaves vary greatly on the gray alder.

Golderle (Alnus incana „Aurea“)

The golden alder belongs to the varieties (cultivars) of the gray alder. The differences to Alnus incana (parent form) are:

  • yellow leaf shoots in spring
  • during the summer: green-yellow
  • towards autumn: increasing greening

Green alder (species)

The green alder is not a tree but a deciduous shrub. The alder leaf of this species has the following characteristics:

  • leaf-blade: elliptic to broadly ovate
  • Leaf margin: double serrate

black alder (species)

  • Arrangement: alternate
  • Leaf color: dark green (upper side), slightly lighter underside
  • leaf-blade: obovate to rounded
  • Length: 4 to 9 centimeters
  • Width: 3 to 7 centimeters
  • Leaf base (blade base): broadly wedge-shaped
  • Leaf margin: roughly doubly serrate
  • Leaf tip: truncate to emarginate
  • leaf surface: glabrous
  • leaf underside: glabrous
  • 8 to 11 pairs of nerves
  • Petiole: 1 to 2.5 centimeters
  • Autumn colour: none to brownish
  • Young leaves: sticky leaf surface
Note: In contrast to gray and green alder, the black alder has a three-strand leaf track.

Schwarz-Erle „Barbata“ (Alnus glutinosa subsp. Barbata)

You can recognize the leaves of this subspecies of black alder by the following characteristics:

  • Leaf color: dark green
  • leaf-blade: oblong-elliptic
  • Length: 4 to 10 centimeters
  • Leaf tip: rounded to just offset
  • Handle: more or less bare

Alnus glutinosa „Imperialis“

The leaves of this variety, also known as fern or split-leaved alder, are:

  • deeply slit
  • filigree

Alders of other origin

Heartleaf Alder

  • Arrangement: alternate
  • Leaf color: shiny dark green
  • leaf-blade: ovate
  • Length: 5 to 10 centimeters
  • Leaf base (blade base): slightly asymmetrical, heart-shaped
  • leaf margin: forward teeth
  • Autumn color: brownish
Note: Heartleaf alder leaves resemble pear leaves in appearance.

Purple Alder

  • Arrangement: alternate
  • Leaf color: dark green (top), underside dull green and lighter than the top
  • leaf-blade: ovate
  • Leaf margin: clearly serrate
  • Leaf tip: distinctly pointed
  • Autumn colour: violet-red

Red Alder

  • Arrangement: alternate
  • Leaf color: dark and glossy
  • leaf-blade: ovate
  • Length: 7 to 15 centimeters
  • Leaf margin: roughly serrate
  • Leaf tip: distinctly pointed
  • Autumn colour: yellow
Note: In contrast to all other alder species, the leaves of the red alder are bent downwards.

Rare alders

Alnus firma

Alnus firma is a rare park tree.

  • Arrangement: alternate
  • Leaf color: green
  • leaf-blade: ovate
  • Leaf margin: serrate with upstanding spikes
  • Leaf tip: distinctly pointed
  • Autumn colour: yellow

Oriental Alder

  • Arrangement: alternate
  • Leaf color: green
  • leaf-blade: obovate
  • Leaf margin: serrate, wavy and slightly indented
  • Leaf tip: distinctly pointed
  • Autumn color: brownish

Wrinkled Alder

The wrinkled alder usually grows as a shrub. You can recognize the leaves by the following characteristics:

  • Leaf color: green (upper side), grey-green to blue-green underside
  • leaf-blade: elliptic to broadly ovate
  • Length: 4 to 11 centimeters
  • Width: 3 to 8 centimeters
  • Leaf base (blade base): wedge-shaped or rounded
  • Leaf margin: doubly serrated, slightly lobed
  • Leaf tip: pointed or blunt
  • leaf surface: glabrous
  • Underside of leaf: brownish hairs on nerves
  • 10 to 15 pairs of nerves

Kira Bellingham

I'm a homes writer and editor with more than 20 years' experience in publishing. I have worked across many titles, including Ideal Home and, of course, Homes & Gardens. My day job is as Chief Group Sub Editor across the homes and interiors titles in the group. This has given me broad experience in interiors advice on just about every subject. I'm obsessed with interiors and delighted to be part of the Homes & Gardens team.

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