Pittosporum tenuifolium 'James Stirling'

 Pittosporum tenuifolium 'James Stirling' (Pittosporaceae)

The down side of a quick growing screening plant like this one is that it may end up being short lived and you are back to square one after just a few years. This plant has the reputation of suddenly turning up its toes especially in warm humid climates or when grown in heavy soils. One by one in a row they will go down without a fight. Of course the appeal of this shrub is the very fine foliage of silvery green clothing the black stems, though this is best when the plants are just a couple of metres tall, as mature specimens, of five metres or more, often become sparse of leaves and reveal a grey trunk and a tarnished sheen. 

A newer cultivar called 'Golf Ball', with its self explanatory name, is worth growing for those who like that touch of glossy silver in the garden on a neat compact plant. It makes an ideal container specimen or as a substitute for Buxus as a low border hedge, though, again, in warm climates it is probably better planted in a raised garden bed or planter box.
2017 update: Evidence suggests that cultivar 'Golf Ball' may revert to being a tall grower.