365 Urban species. #359: American Holly, #360: European Holly

Photos by cottonmanifesto. Locations throughout Brookline Village/Longwood Medical area.

Urban species #359: American holly Ilex opaca
Urban species #360: European holly Ilex aquifolium

A plant that in winter has rich green foliage and bright red berries suggests many things in the human imagination. For many centuries these plants have reminded people that though life seems to have abandoned us in winter, it goes on, and will return in spring. A recurring religious theme, in many cultures, has personified this hope with a god that dies and comes back. In Christianity, it is said that Jesus' blood will save us--the blood red berries of holly remind Christians of this belief. The sharp leaves of the holly evoke the crown of thorns He wore, or the nails used to crucify Him. It is small wonder that the hollies have been a staple of winter decorations, and in relatively recent times, Christmas decorations.

For plants, having green foliage and red berries is a very earthly matter of life and procreation. Most hollies are green year-round, though some, such as winterberry, are deciduous. Evergreen hollies that occur in cold places have waxy leaves that resist water loss. Red berries contrast starkly with the green foliage, not because that makes for better decorations, or to make a religious statement, but to advertise their food value to the birds. The fruit (which are technically drupes, not berries) persist through the winter, because they don't taste good to birds until they have been frozen and thawed. In North America, goldfinches and cedar waxwings, among many other species, eat the fruit and disperse the seeds, allowing the plant to reproduce. The fruit is mildly toxic to humans, but squirrels and other mammals eat them. They edges of the leaves of European and American hollies are thorny, which helps keep mammals, which are not efficient seed-distributors, from eating the fruit. Nesting birds are likewise protected from predacious tree-climbers in the holly's thorny refuge.

Each holly plant is either a male or female (monoecious like ailanthus and ginkgo as opposed to dioecious, like ragweed and Norway maple, which have male and female flowers on the same individual). This means that in order to have the red berries present, landscapers and decorators must choose female plants. Those wishing to sexually propagate holly are obliged to include males nearby. Their flowers are pollinated by wasps, moths, and bees, and the honey made by honeybees from holly nectar is said to be of high quality.

There are a few dozen different species of holly, the two most commonly planted being American (I. opaca) and European, or common (I. Aquifolium) hollies. American holly is native to the middle latitudes of east coast of North America, and has generally less glossy leaves and shorter thorns than European holly. It is the only holly native to North America that may grow bigger than a large shrub, becoming a small tree (up to 50 feet tall). European holly has been widely planted around the world, and is considered invasive on the west coast of North America, as well as in Australia and New Zealand. A myriad of cultivated varieties exist, including some with variegated leaf color, and some with yellow, rather than red fruit.



I would greatly appreciate some photos of American holly, as it seems most of the plantings nearby appear to be European.

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