The genus Leptospermum (common name Ti-tree or Tea-tree) belongs to the myrtle family Myrtaceae. About 80 evergreen shrubs and small trees make up the genus and there are now a number of cultivars from which gardeners can choose. Cultivars are selected for flower colour and size, and for plant vigour. The flowers have a cup-shaped base which holds nectar. This is surrounded by 5 petals. The leaves are small, narrow and often aromatic.
Leptospermum nitidum ‘Copper Sheen’ grows to 3 metres and has reddish foliage with bright, deep red new growth. The flowers are an attractive lime-yellow of around 2.5cm diameter. The main flowering season is from September to November. This species is worthy of cultivation for the foliage alone but the flowers are also attractive. Pruning will help promote new growth.
Leptospermum ‘Horizontalis’ is a dense, spreading shrub with prickly, pointed leaves. It bears profuse, white, ti-tree flowers from October to December. It is a hardy and reliable low shrub that tolerates quite a wide range of conditions. It is equally at home on sandy or gravelly soils and can be planted in exposed coastal positions.
Three cultivars developed from Leptospermum polygalifolium are Cardwell, Pacific Beauty and Pink Cascade (which has Pacific Beauty as one of its parents). Cardwell is a most attractive small shrub with a weeping habit, Pacific Beauty has pendulous branches and an abundance of white flowers which Pink Cascade is a semi-prostrate shrub with arching branches and an abundance of two-toned pink flowers in spring. Ane, as if that isn’t enough, the flowers appear again in equal profusion in autumn.
‘Julie Ann’ is a cultivar of Leptospermum rotundifolium. It grows only to 30cm in height and has a spreading habit. It also has the most attractive pale mauve flowers.
Leptospermum scoparium has given rise to some lovely cultivars including Kiwi, a dwarf form with single light red flowers, and Nanum Kea which has profuse pink flowers.
Another striking cultivar is Aphrodite. This is a medium shrub of about 2.5 metres high. The leaves are narrow and lanceolate in shape. The pink flowers are larger than the run-of-the-mill tea-tree flowers and have a green centre. This is a hardy shrub if planted in moist soils in temperate climates. It will cope with full or partial sun and may be pruned severely if required.
Crossings between Leptospermum rotundifolium and L.spectabile has resulted in the development of L. ‘Rhiannon’, a medium shrub which grows to around two metres. It has an upright habit and mauve-pink flowers with green centres. The flowers have a diameter of about 20mm and the narrow leaves are about 10mm in length.
The leptospermum makes an attractive screening plant. Cultivars need to be propagated from cuttings if they are to retain their particular characteristics.