There are more than 32 species of lavender plus numerous hybrids and cultivars.
Which most gardeners know as French lavender - a fat velvety bush with toothed, ridged leaves and dense flower heads – not fully hardy but very good for decorative use. Some varieties have grey-blue foliage, others grey-green, a variation which can be used to good effect in planting schemes.
Variously called Spanish or Mediterranean lavender - a dense, bushy shrub with smooth-edged leaves and boxy little flower heads with large, colourful bracts at the tip. The flowering season, from late winter into spring, is short but both plants and flowers are highly decorative and there are cultivars in every shade of mauve and purple as well as maroon and white. Fairly frost-hardy.
Lavandula x allardii
This is a hybrid of L latifolia (the medicinal lavender) and L dentata, resulting in a very large, handsome shy-flowering bush with broad scallop-edged leaves, which is the preferred variety for formal hedging.
Lavandula x intermedia
This is an old, very variable hybrid, a cross between Langustifolia and L latifolia, resulting in grey to silvery bushes with smooth or scallop-edged leaves, elongated flower heads on long stems and a marvellous scribbly, fine-textured growth. The variety "Margaret Roberts" is registered in South Africa. It flowers nearly all year round and is fully hardy. This lavender is often incorrectly named English Lavender.
Australian lavender – has a very different look to the others and an altogether more open growth habit. It has feathery leaves and branched flower spikes of deep violet-blue. Frost-tender.