Friends of Belfast Botanic Gardens

Tree of the month series - this series of short articles about trees in the Belfast Botanic Gardens is compiled by members of the Friends group and Gardens staff. The series will gradually build up to a comprehensive archive of information about the trees in Belfast Botanic gardens. Each article will illustrate the tree in Belfast together with information from a range of sources elsewhere. Click here for the rest of the trees

Tree of the Month, February 2009

Holly- Ilex aquifolium and its varieties

by Jonathan Pilcher

The holly genus, Ilex, has some 400 species, but only one is native to the British Isles. Ilex aquifolium is a medium sized tree often forming an understory in native woodlands of oak. The tree will reach 20m and will grow from suckers hence often forming a clump of trees. The leaves are evergreen, thick with a glossy upper surface and normally with sharp spines.The fertile branches usually carry leaves that are almost spineless. Hollys are dioceous (ie having separate male and female trees) so some trees, the males, will not produce berries. The flowers are small and white and produced in late summer. The female flowers may appear to have stamens but on close inspection these are seen to be shrivelled. Fruit production depends on the presence of both male and female trees and fruit ripens in December. The young stems of holly start off green then turn a silvery grey. The wood is white, very hard, dense and used in fine carpentry and inlay.

The RHS Plant Finder lists 54 cultivars of I. aquifolium in cultivation and 21 cultivars of the hybrid species Ilex x altaclerensis. Three of the commonest cultivars are "Golden King", a gold-edged variegated form which is surprisingly a female and produces berries, "Silver Queen" is silvered variegated and is (you guessed? ) a male producing no berries. "Bacciflava" is a non-variegated form with yellow berries.

Belfast Botanic Gardens has the species and a number of cultivars. One of the best specimens is on the corner of the path from the Botanic gate to the Palm House. This is a female silver-edged cultivar of Ilex aquifolium, probably 'Argentea Marginata'

large silver variegated holly near Botanic Av. gate of the Belfast Botanic Gardens	silver variegated form of holly
female flowers of holly	gold-variegated form of holly - probably Golden King
These all-white leaves occur occasionally on silver variegated forms of holly. They are non-photosynthetic and live at the expense of the rest of the tree.	Leaves from the same holly tree; the left from a flowering branch, the right from a young branch.

Photos taken in 2008 in Belfast Botanic Gardens and the authors garden. Copyright Jon Pilcher