Olea europaea L.
Eng.: Wild olive. Spa.: Acebuche, olivo silvestre. Fre.: Olivier sauvage, oleastre. Ara. (the wild form): Zebbudj, zebbur, azebbuj (the cultivated form): zitun, zeitun, zaitun, amurqa, zeitar. Tam. (the wild form): Azebudj, tazbbujt, berri, (the cultivated form): azemmur, zzit, tesefta, tahatimt, amil.
Evergreen tree, hermaphrodite, up to 10 m in height, although in rugged mountains and very dry areas it commonly adopts a shrubby habit, especially if there is pressure from livestock in the area. Adult plants present a regular shape, with oval or round crown. Trunk slightly tortuous, thick, short, as it promptly branches. Bark highly fissured, especially in the base of the trunk, greyish-brown. Branches erect-patent, flexible when highly grazed, with slightly spiny bark, smooth, light grey, ashy. Branchlets greenish-ashen. Leaves opposite [(0.5)1-8 × 0.3-1.2 cm], 2-7 times longer than wide, from oval-lanceolate to oblanceolate or clearly lanceolate —in poor growing conditions they can be very small, elliptic or obovate— with margin entire and slightly revolute, attenuated at the base, with a short petiole, acute, sometimes mucronate, coriaceous, matt green-greyish on the upper side and ashen-silvery on the underside. Inflorescence in axillary or terminal panicles. Flowers white, small, subsessile. Calyx cupuliform, greenish, with 4 small teeth. Corolla with a single piece, with short tube and 4 white lobes as petals open in the shape of a star. Stamens 2, born fused to the corolla tube. Anthers yellow, very showy. Fruit (0.5-4 cm) a “drupe” (this was the Roman name of the olive) ellipsoid, green at first and shiny black when ripe; it contains a stone (endocarp), very hard or soft, with a single seed.
Flowering:
April to June.
Fruiting:
October to December.
Habitat:
Indifferent to the type of substrate. It grows in almost all types of terrain, from sea level to the mid mountains and from humid forests to Saharan steppes. From arid (in shady areas or areas with high edaphic humidity) to subhumid bioclimate, on thermomediterranean and inframediterranean floors. It withstands heat and drought, but not heavy frosts.
Distribution:
Mediterranean region. In North Africa from the Mediterranean coast to the northern Sahara, completely missing from high mountains, because of the cold.
Observations:
The wild olive is a tree of great importance in forestry in North Africa. It represents the largest area of potential forest vegetation of the region, above the holm oak, the cork oak, the thuya and the pine. However, whereas good forests of the latter species still survive, there is not a single remaining wild olive native forest. Large semiarid and arid, dried and dusty North African areas used to be lush and impenetrable forests of wild olive trees. The last forest remnants can still be seen in some Muslim cemeteries or marabouts, where vegetation has not been damaged for centuries.
Forests of wild olive trees were mainly composed of the wild olive, as the dominant tree species, and the mastic (Pistacia lentiscus), the mock privet (Phillyre alatifolia), the Kermes oak (Quercus coccifera), the thuya (Tetraclinis articulata) and the fan palm (Chamaerops humilis), as main companion species that always reached tree size. Between these trees, numerous species of lianas used to climb, many of them woody, such as Ephedra fragilis, Clematis cirrhosa, C. flammula, Lonicera implexa, Asparagus altissimus or Smilax aspera. The group of trees, shrubs, lianas and other species formed a truly impenetrable forest, genuinely Mediterranean, that kept a very thick moist and fertile soil, whilst also serving as habitat for a rich faunal community.
Nowadays the use of wild olive trees as a species in reforestation should be encouraged in semiarid and arid areas of North Africa, over the use of introduced taxa (exotic acacias and eucalyptus), both against erosion and desertification as well as to promote the conservation and recovery of the rich biodiversity of the region.
Currently 6 subspecies tend to be differentiated, of which 4 are in North Africa. O. europaea subsp. europea, with a short inflorescence [1-3(4) cm] and large drupes [1-3(4) × 0.5-2(3) cm] with thick mesocarp, which would encompass the traditional var. europaea, widely cultivated, and var. sylvestris, distributed through the Mediterranean. O. europaea subsp. cuspidata (Wall. ex G.Don) Cif. [O. africana Mill., O. chrysophylla Lam., O. europaea var. verrucosa Willd., O. verrucosa (Willd.) Link, O. ferruginea Royle, O. cuspidata Wall. ex G.Don, O. somaliensis Baker, O. europaea var. nubica Schweinf. ex Baker, O. schimperi Gand., O. aucheri Chev. ex Ehrend., O. europaea subsp. africana (Mill.) P.S.Green] (Ara.: Dada’a) with leaves tinted reddish on the underside, longer inflorescence (4-10 cm) and smaller drupes (0.5-1 × 0.4-0.5 cm) with thin mesocarp; which is distributed over the rocky hills SE of Egypt, the Sudanese coast, tropical Africa, Arabia, Iran, Pakistan, Afghanistan and China. O. europaea subsp. laperrini (Batt. & Trab.) Cif. (O. laperrini Batt. & Trab.) (Tamahaq: aleo, aleu, oleo, tafeltasset) with opposite leaves [1-8 × 0.2-0.7(1) cm], ± 8-15 times longer than wide, from linear to linear-lanceolate, and slightly fleshy drupes, with soft endocarp with membranous walls; endemic to the mountains of the central Sahara (1,300-2,500 m in altitude), relatively common in the Ahaggar Massif, rarer in the mountains of Tefedest, Tassili-n-Ajjer, Mouydir, Tibesti and Aïr; to the SE it reaches the Marrah Massif and other mountains in Darfur. O. europaea subsp. maroccana (Greuter & Burdet) P.Vargas, J.Hess, Muñoz Garm. & Kadereit (O. maroccana Greuter & Burdet) with upright branchlets, with elongated internodes (2-6 cm); narrower leaves, with very short petiole (1-2 mm); inflorescences lateral (5-7 cm long) and terminal (6-12 cm long); bracts (3-4 mm long) lanceolate, obtuse; flowers with pedicel 2-4 mm, urceolate calyx, with straight apex, and ovate-cylindrical exserted stigma (1 mm long); endemic to SW Morocco, growing from the S slope of western High Atlas to the western Anti-Atlas.
Conservation status:
O. europaea is a common and widespread species, but some of its subspecies, such as subsp. laperrini are rare and with a small distribution area.
Currently, it has not been assessed at a global level in the IUCN Red List of Threatened Species. In Algeria, subsp. laperrini is included in its List of protected non cultivated flora (Executive Decree 12-03 on 4-Jan-2012). In the Red List of vascular plants of Egypt (Flora Aegyptiaca Vol 1, 2000) subsp. cuspidata is listed as “Vulnerable”.