Species Profile: English Holly

Deck the halls with boughs of invasives?

Although it’s often viewed as a pleasant symbol of the holiday season, English holly Ilex aquifolium is actually an invasive nuisance in British Columbia, along the US west coast, and in Australia and New Zealand.  Originally from Europe and northern Africa, English holly has been intentionally introduced around the world as an ornamental plant.  Where it has escaped from gardens, English holly can grow into large prickly masses that can crowd out native vegetation and impede recreational activities such as hiking through the forest.

English holly photo courtesy of Wikimedia Commons

Although you may most often encounter it as small decorative boughs, English holly grows as a massive evergreen shrub in the wild, reaching heights of over 10 meters.  The shrub is characterized by smooth gray bark and distinctive green leaves with variable numbers of sharp spines along their margins.  English holly is a dioecious plant, and females produce bright red berries <1cm in diameter.  These berries are toxic to human beings but are tolerated by birds and other forest critters.  Because holly bears its fruit in the winter, the berries can represent an important food subsidy for wildlife when resources are otherwise scarce.  However, the fruit’s seeds can survive passage through animal digestive tracts, contributing to rapid dispersal.

Although the toxic berries are not safe for human consumption, there are other options for an invasivore who’s feeling festive.  The leaves and berries maintain their bright color and pleasant scent even after being pruned and taken indoors, and English holly has been used as winter decoration for centuries.  For example, a few trimmings can make a fine wreath.  English holly leaves and berries can also make a delightful addition to a winter potpourri.  So happy crafting, invasivores!


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