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Quercus ilex
Holm oak
Holm oak, holly oak, evergreen oak (Eng); encina, carrasca, chaparro (Spa); alzina (Cat); artea (Baq); aciñeira (Glg); azinheira (Por).
Non-Native
Bread of wheat, firewood of holm oak, and wine from the vine, sustain the home”.
Popular Spanish sayingDESCRIPTION
Tree of variable size that rarely exceeds 25 m in height, with a low, dense and rounded crown. Its bark is thick, ash-coloured, and cracked with shallow fissures. Its twigs are densely covered with a whitish felt (flock). The leaves are simple, persistent, alternate, leathery and variable in form. They can be rounded, elliptical or lanceolate, with a blunt or sharp tip. The margin can be entire or have little spikes (mainly the leaves of the lower branches and new shoots), the upper side is dark green, and the underside is covered with a dense, whitish, velvety-looking tomentum. In spring the male flowers are borne in hanging, yellow or ochre groups (catkins), whereas the discreet female blooms generally appear singly, on the same tree (monoicous). Some holm oaks have more female flowers, others have more males, giving rise to the Spanish saying: “The holm oak with 'mocos' [male catkins], adds little to the heap”. The fruit are ovoid acorns, up to 3 cm long, with a single seed, and are joined to the tree by a tightly-scaled cupule (husk). They can be sweet or bitter.
ECOLOGY
The holm oak is indifferent to soil type, although it prefers limey substrates and avoids land that is too sandy, saline or waterlogged. In its natural range it can be found in mild coastal zones as well as in the interior, where the temperature differences are more pronounced. It is a tree that is tolerant of summer heat and prolonged droughts, frosts and extreme exposure to sunlight. As it can grow in somewhat moist substrates, as long as they are well-drained, it has prospered in the Canarian monteverde forest domain, where isolated specimens can be found.
DISTRIBUTION
The holm oak lives mainly throughout the Mediterranean region, from where it was introduced into the Canary Islands. It is considered to be established in the wild on La Palma, La Gomera, Tenerife and Gran Canaria, although today there few naturalised specimens.
