Alnus lusitanica Vít, Douda & Mandák

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Credits

Tim Baxter & Hugh A. McAllister (2024)

Recommended citation
Baxter, T. & McAllister, H.A. (2024), 'Alnus lusitanica' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/alnus/alnus-lusitanica/). Accessed 2024-07-20.

Genus

  • Alnus
  • Subgen. Alnus, Sect. Glutinosae

Glossary

emarginate
Notched at the apex.
obtuse
Blunt.

Credits

Tim Baxter & Hugh A. McAllister (2024)

Recommended citation
Baxter, T. & McAllister, H.A. (2024), 'Alnus lusitanica' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/alnus/alnus-lusitanica/). Accessed 2024-07-20.

Tree to 25 m. Bark grey to brownish grey, becoming fissured with age. Buds obovate, glabrous to densely hairy, 2–3 bud scales. Juvenile buds and leaves often viscous. Twigs smooth, extension growth glabrous. Leaves 5–7 × 4.5–7 cm, suborbicular to obovate, apex rounded to obtuse, base cuneate, margin obtusely dentate to lobulate, abaxially glabrous or rarely sparsely pubescent, with hairy domatia in vein axils, craspedodromous, with 6–9 pairs of lateral veins. Petiole 1.5–3 cm. Staminate inflorescences terminal, 30–75 × 2–6 mm at anthesis. Pistillate inflorescences below males. Fruit dark brown, 10–23 × 7–11 mm, peduncle 8–21 mm, dark brown or black in maturity. Seeds dark brown. Flowering February to April. Tetraploid, 2n=56. (Vit et al. 2017).

Distribution  MoroccoPortugalSpain

Habitat Frequently flooded ash-alder woodland in riparian habitats, and in seepage and wetland forests in humid and warm areas across a broad elevational range.

Conservation status Data deficient (DD)

Alnus lusitanica is a recently described species from the Iberian Peninsula and northern Morocco (Vit et al. 2017). It is most closely related to A. glutinosa and was split (alongside A. rohlenae) when a consitent pattern of polyploids were discovered in southern Europe, although the issue has been known for many years (McAllister, pers. obs.). A. lusitanica is an autotetraploid derived from A. glutinosa, most likely during a period of isolation during glaciation, in refugia in this region. This pattern is not repeated in the Caucasus, where it might be expected, as A. glutinosa subsp. barbata and subsp. betuloides always appear to be diploid.

Alnus lusitanica could easily be mistaken for A. glutinosa but differs in its female catkins with longer peduncles, the leaf apices only rarely emarginate and more commonly rounded to obtuse, oval lenticels, and longer male and female catkins. It occurs in Spain, Portugal and Morocco; material with these characters outside of these regions will be something else. In the wild it can be abundant in appropriate habitats. It is not known whether this species is in cultivation but it could be very promising as a drought-tolerant form of A. glutinosa.