This is from the Northen Ireland Police website for garden security:
Creeping Juniper Juniperis horizontalis 'Wiltonii' - Also known as 'Blue Rug' because it has long branches and its prostrate shape forms a flattened blue carpet. It has a thorny stem and foliage.
Blue Spruce Picea pungens 'Globosa' - Rigid branches, irregular dense blue, spiky needles. Height 1-1.25m x 75cm - 1 m. Slow growing. Moist rich soil.
Common Holly Ilex agulfolium - Large evergreen shrub, dark green spiked leaves. Large red berries on female plants only. Any well drained soil. Plant with garden compost and bone-meal.
Giant Rhubarb Gunnera manicata - Giant rhubarb-like leaves on erect stems, abrasive foliage. Can grow up to 2.5m high. Plant by water-side for effect.
Golden Bamboo Phyllostachys aurea - Very graceful, forming thick clumps of up to 3.5m high. Less invasive than other bamboos. Hardy. Young shoots in spring.
Chinese Jujube Zizyphus sativa - Medium sized tree with very spiny pendulous branches. Leaves glossy bright green. Bears clusters of small yellow flowers.
Firethorn Pyracantha 'Orange Glow' - Flowers white in June, with bright orange-red berries. Thorny stem. Height 10-15ft. Suitable for north or east-facing wall or as impenetrable hedging.
Shrub Rose Rosa 'Frau Dagmar Hastrup' - Excellent ground cover, pale pink flowers, very thorny stem. May to September. Plant with garden compost and bone-meal.
Pencil Christmas Tree Picea abias 'Cupressina' - Medium-sized tree of columnar habit, with ascending spiky branches. Attractive form with dense growth. Avoid dry chalky soils.
Juniper Juniperus x media 'Old Gold' - Evergreen. Golden-tipped foliage. Prickly foliage. Height 2ft. Spread 6ft. Low growing. Excellent ground cover.
Purple Berberis Berberis thunbergil 'Atropurpurea' - Rich purple foliage. Thorny stem. Medium-sized deciduous. Any soil sunny position.
Mountain Pine Pinus mugo 'Mughus' - A very hardy, large shrub or small tree, with long sharp needles, of dense, bushy habit. Leaves in pairs, 3 - 4cm long, rigid and curved, dark green, cone.
Blue Pine Picea pungens 'Hoopsii' - Small to medium-sized tree, spiky needled stem, densely conical habit, with vividly glaucous blue leaves. Likes moist, rich soil.
Oleaster Elaeagnus angustifolia - Small deciduous tree, about 4.5 to 6 m (15 to 20 feet) high. Smooth, dark brown branches that often bear spines and narrow, light green leaves that are silvery on the undersides. The flowers are small, greenish, fragrant, and silvery-scaled on the outside, as are the edible, olive-shaped, yellowish fruits, which are sweet but mealy. Hardy, wind resistant, tolerant of poor, dry sites, and thus useful in windbreak hedges.
Blackthorn Prunus spinosa - Also called Sloe; spiny shrub. Usually grows less than 3.6 metres (12 feet) tall and has numerous, small leaves. Its dense growth makes it suitable for hedges. White flowers. Bluish-black fruit is used to flavour sloe gin.
Fuschia-flowered Gooseberry Ribes speciosum - Fruit bush, spiny, produces greenish to greenish-pink flowers in clusters of two or three. Extremely hardy, thrive in moist, heavy clay soil in cool, humid climate.