#laurel forest

Enchanting Photos of Madeira’s Ancient Fanal Forest Filled With 500-Year-Old Trees - Portugal

Fanal is part of the Laurisilva forest, a UNESCO World Heritage Site known for its beauty and ecological importance. Incredibly, 15 to 40 million years ago, much of Southern Europe was covered in this type of laurel forest. Now, it can only be found in Madeira, the Azores, and the Canary Islands.

Photographer: Albert Dros 

Ilex aquifolium is known as common holly, European/English holly, sometimes Christmas holly, and often just holly.  It grows as an evergreen tree or shrub/bush.

Kingdom: Plantae

Clade: Angiosperms (flowering plants)

Clade: Eudicots (also known as tricolpates & non-magnoliid dicots)

Clade: Asterids

Order: Aquifoliales

Family: Aquifoliaceae

Genus: Ilex (about 480 holly species).  Ilex is the only living genus in the Aquifoliaceae family.

Species: Ilex aquifolium

Holly trees.

Holly bushes.

Holly hedges.

Ilex aquifolium is native to western & south-western Europe, south-west Asia, and north-west Africa.  It is one of Britain's few native evergreen trees.

Holly is often found in the shady undergrowth of oak forests, and in beech hedges, but sometimes forms a dense thicket as the dominant species.  It adapts very well to various conditions, but requires moist, shady environments – e.g. forests, shady slopes, cliffs and mountain gorges.  It can tolerate both frost and summer drought.

Holly is a “pioneer species” that repopulates the margins of forests or clearcuts.  It grows slowly, and usually doesn't manage to mature fully, due to cutting or fire.

While it can grow to over 10m tall, common holly is usually about 2-3m tall and broad.  It has a straight trunk and pyramidal crown, branching from the base.  It can live up to 500yrs, but usually doesn't make it to 100yrs.

Pure stands of holly can grow into a labyrinth of holly vaults, where deer and thrushes can find refuge.  Smaller birds are protected among the spiny leaves.

The woody stems can be 40-80cm wide in diameter, or even over 1m wide (although this is rare).  The leaves are 5-12cm long and 2-6cm wide, and last about 5yrs.  They are dark green on the top side and lighter on the bottom; they are roughly oval-shaped, leathery, and glossy.

In young trees, the leaves are spiky, with 3-5 spikes (or spines) on each side.  In mature trees, only the lower limbs have spiky leaves. This heterophylly (growing different types of leaves at the same time) is an epigenetic reaction to animals eating the leaves.

Different leaves from the same holly tree.

Holly is dioecious – there are male and female plants.  The plants usually begin flowering between 4 and 12 years old, and this is when they can be differentiated.  Male flowers are yellowish-white and appear in axillary shoots (diagram below), while female flowers are white or slightly pinkish-white, smaller than the male flowers, and grow separately or in groups of three.  The female flowers have four petals and four sepals partially fused at the base.  All holly flowers are four-lobed, and pollinated by bees.

Axillary buds are located at the intersection of the leaf and stem of a plant.

Only the female plants have berries, so there need to be male plants nearby to fertilize them.  The holly berry is a bright red or bright yellow drupe (stone fruit) about 6-10mm in diameter.  The berries mature around October/November (late autumn), but they are very bitter at this stage due to their ilicin content.

Birds, rodents, and larger herbivores usually eat them in late winter, after the frost has made them softer and more edible, and they fall to the ground.  They are an important food for birds in winter, because of the scarcity of resources.  Each fruit has 3-4 seeds, and they germinate during the second or third spring.

Bees, wasps, small butterflies and flies obtain nectar from the flowers. Phytomyza ilicis, the holly leaf miner, causes the pale patches on the leaves.

Leaf miner damage.

The berries are poisonous for humans.  They contain alkaloids, caffeic acid, caffeine, saponins, theobromine, and ilexanthin (a yellow pigment).  They are emetic (i.e. they cause vomiting), possibly due to the compound ilicin.  The berries are also poisonous for cats & dogs, because of the caffeine & theobromine.

Holly isn't native to North America, but it is very invasive along the west coast of Canada and the USA.  It spreads quickly into native forests, thriving there and crowding out native species.  In the state of Washington, it is on the Noxious Weed Control Board's monitor list.  In Portland (Oregon), it is listed as a Class C invasive plant.  Holly is also an invasive plant in Hawai'i.

During the [early?] Cenozoic Era (66 million years ago until today), Europe, the Mediterranean, and north-western Africa had a wetter climate than now, and were mostly covered in laurel forests.  This is a type of subtropical forest that grows in regions with high humidity, and mild temperatures that are relatively stable.  Plants from the Lauraceae (laurel) family are not necessarily part of a laurel forest.  What mostly grows are broad-leaved, evergreen tree species with glossy, elongated leaves.  Holly grew well in these laurel forests, and many of the present-day Ilex species, including common holly, were found there.

However, the Mediterranean Basin dried up in the Messinian Salinity Crisis during the Pliocene Epoch (about 5.33 million years ago – 2.58 million years ago), forcing the laurel forests to gradually retreat.  They were replaced with more drought-tolerant sclerophyll plant communities.  Most of the remaining laurel forests in the Mediterranean region probably died out around 10,000 years ago, at the end of the Pleistocene Epoch.

Today, holly is also commonly found in garigue and maquis, scrubland and shrubland regions in the Mediterranean areas.

From the 1200s – 1700s, common holly was grown as winter fodder for cattle and sheep (this was before turnips were introduced).  Less spiny varieties were preferred, and the leaves near the top of the tree were most suitable, as they aren't spiny at all.

In the past, holly was one of the traditional woods used to make the Great Highland bagpipe.  However, imported dense, tropical woods eventually took over.