Frangula alnus Mill.
Rhamnus frangula L.
Eng.: Alder buckthorn, glossy buckthorn, breaking buckthorn. Spa.: Arraclán. Fre.: Nerprun bourdaine. Ara.: Ahmeraï.
Shrub or small tree, deciduous, dioecious, unarmed, up to 5(8) m in height. Trunk well defined, with brown-blackish bark. Branches and branchlets alternate, glabrous, reddish-brown, smooth and shiny. Leaves (2-8 × 1-4 cm) alternate, oval-oblong, ending in an acute tip, attenuated or rounded at the base, with subentire or dentate margin, with obtuse teeth; veins highly conspicuous (7-11 pairs), lateral, almost straight and parallel. Young leaves slightly pubescent then glabrous, green on both sides. Petiole well developed, with promptly caducous herbaceous stipules. Inflorescence in axillary cymes with about 4-5 flowers. Calyx shortly campanulate, green, with 5 longly triangular sepals; petals 5, whitish, oval, each wrapping around a stamen, included in the calyx. Fruit a globose drupe, 5-10 mm in diameter, green at first, then red and finally black. Seeds 2-3, without a groove on the inside.
Flowering:
April to July.
Fruiting:
August to October.
Habitat:
Forests with cool and humid soils, usually along mountain rivers and streams, or on the plains, along rivers and lakes. In subhumid to humid bioclimate, on thermomediterranean to mesomediterranean floors.
Distribution:
Palearctic. In North Africa it is a fairly rare species. In Morocco it grows only sporadically in the Larache-Tangier-Ketama triangle; in Algeria it is located in the NE region, in the lakes region of the El Kalaa (Lake Sebaa); and in Tunisia, in the NW region, in the alder groves of the River Zeen (near Ouchtata). There are 2 recognised subspecies: F. alnus subsp. alnus, of Euroasia and the aforementioned areas of Morocco, Algeria and Tunisia; and F. alnus subsp. baetica (Willk. & E.Rev.) Rivas Goday ex Devesa, Ibero-North African (W of the Rif, at least in Jebel Buhaxem -Xaüen-). The former with deciduous leaves, with a length/width ratio of (1.2)1.4-2.6, herbaceous, with 7-9 pairs of secondary veins; the latter with biennial to deciduous leaves, with a length/width ratio of 1.6-3.5, chartaceous, with 7-11 pairs of secondary veins.
Conservation status:
Common and widely distributed species in the Palearctic but very rare in North Africa. Currently, it has not been assessed at a global level in the IUCN Red List of Threatened Species. In Tunisia it is included in its List of native species that are rare and threatened with extinction (Order of the Ministry of Agriculture and Water Resources, 19-July-2006).