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186 M.G. Maw
Background R. cathartica was introduced into North America as a hedge and shelterbelt shrub or as
an ornamental in parks and gardens. It varies considerably in size, ranging upwards of 10
m high under favourable conditions but is more usually less than half that height. It is
very bushy, often many stemmed, and the shoots and branches terminate in a sharp
spine. The leaves are alternate, smooth, and elliptical with toothed margins. The flowers
are in the axils of the leaves, small, greenish, and dioecious. The mature fruit is a bluish
to nearly black drupe, bitter to the taste, and about 8 mm in diameter. The seed is 3-4
grooved.
Reproduction is entirely by seeds which germinate 90-100% when the fruit is just
ripe. The plant regenerates quickly from cut stems and after burning and grazing
(Montgomery 1956, Mulligan 1952, Rydberg 1932).
(a) Habitat
In eastern Canada, buckthorn is found along fence rows, along roadsides, in open
woods, and along the gently sloping banks of lakes, rivers, and streams, it is often seen in
solid masses along every fence row in many locations, but apparently is not found to any
extent in pastures. Plants of about 2.5 m can be found in wood openings with many
smaller plants and seedlings in the more shaded locations. Where the trees are removed,
these smaller plants grow rapidly forming a forest of buckthorn. It tends to be more
commonly on soils of high moisture content than on light, dry soils (Mulligan 1952).
In Manitoba, there are relatively few areas outside of the larger towns and cities where
buckthorn is found (Peturson 1954). It is concentrated in Winnipeg, Brandon, and near
Macdonald, generally as park and hedgerow plantings (Bassett 1958), and in a sheltered
ravine near Morden (Harder 1975).
In England, it is found chiefly on alkaline peat and limestone soils (Godwin 1943).
(b) Geographic range
In England, it is found in the midland, southern and eastern counties, but is absent
from Cornwall, North Devon, Northumberland, and western counties of Wales.
In Ireland, it is present in a wide belt across the central Irish plain, but absent from the
southern counties and absent or rare in the northern.
It is doubtfully native in Scotland, except possibly in Dumfries.
Its range extends through the greater part of Europe to 60" 48' in Norway and 61 0 41' in
Sweden, in southern Finland, Esthonia, and across Russia into western Asia, Afghanistan,
and Turkestan.
It is present in southern Europe to middle and eastern Spain and Macedonia, and
sparingly at high altitudes in Morocco and Algeria, but absent in the Balearics, Corsica,
and Sardinia, also from western Siberia, Transcaucasia to Altai (Godwin 1943).
In North America, R. cathartica is found in the New England states, Virginia,
westward to Illinois, Missouri, Wisconsin, Minnesota (Fernald 1950), Quebec, Ontario
Manitoba, and to a limited extent in Saskatchewan, Alberta, and the Maritimes.
(c) Uses
R. cathartica is a useful hedge and shelterbelt shrub and as such has been extensively
planted in Ontario and Quc!bec and to a lesser extent in other provinces. It is also used as
an ornamental in gardens and parks.