Leptospermum scoparium is commonly called Mānuka. It is a scrub-type tree abundant around coastal areas and where land previously cleared for forestry or farming is now being left to return to native forests. Mānuka is typically one of the first plants to regenerate on cleared land. It can be found in many different habitats from coastal situations to low alpine habitats. It colonizes wetlands, river gravels and dry hillsides. When mature, it is very tolerant of drought, waterlogging, strong winds and frost and it can grow in various inhospitable conditions. However, they are often considered unwanted scrub and are burned or poisoned in order to clear land for pasture. Removing mānuka often eliminates the potential for further forest regeneration.
Leptospermum scoparium is an evergreen shrub that features small, prickly, needle-like leaves, which are aromatic when crushed. The leaves are hard and prickly to grasp. This makes it easy to distinguish from Kānuka: Mānuka is ‘mean’ or prickly whereas Kānuka is ‘kind’ or soft. Bark is flaky. The wood is tough and hard. It is typically a shrub growing to 2–5m but can grow up to 15 m. In early summer, the plant produces showy single or double white, pink, or red blossoms. Flowers smell very sweet and provide an important source of pollen and nectar for native bees, flies, moths, beetles and geckos. Flowers are followed by seed capsules that are persistent so invariably mature plants possess at least some capsules.
Mānuka (called ‘tea tree’ by Captain Cook) is a variable plant ranging from flat creeping forms and small shrubs to tall trees. There are many cultivars that are available in garden centres worldwide. Although variable, all the forms of this species are unified by their sharp-tipped leaves, large, solitary white or pink-flushed flowers, with distinctive short, dark red stamens, and persistent greyish-white nut-like capsules. Because it is so variable, it is wise to plant only a locally sourced form. It would be better to avoid using cultivars if planting into gardens abutting indigenous forest remnants.
Mānuka plants are sometimes covered with sooty mould, a black fungus that feeds on the honeydew produced by scale insects. While the sooty mould can be unsightly, it should not affect the overall health of the tree. Does not like root disturbance when planting. Very hardy, fast growing. Tolerant of wet / dry, full sun/semi shade.
Although widespread and common, some stands are at risk from clearance for farmland or through felling for firewood. The recent (2017) arrival of myrtle rust may pose a more serious threat to Leptospermum. However, as of 2018 there have been very few occurrences of myrtle rust on Leptospermum.
Before the arrival of Captain Cook and the early settlers, Mānuka was popular with Maori for the extensive uses of its wood and bark. (for more information, click here.) Using bees to collect nectar for honey only came much later with Mary Bumby who brought two hives of honey bees with her from Sydney in 1839. Mānuka honey, a popular honey for culinary uses and alternative medicine, is produced from the nectar that bees gather from this plant. Chemical tests have shown that mānuka pollen, and honey derived from it, contains powerful insecticides and anti-bacterial agents that can help fight intestinal worms and bacterial infections. Mānuka oil is now sold in New Zealand and overseas in various cosmetics and healthcare products.
Kānuka (Kunzea spp), although superficially similar to mānuka, is a rather different plant. In its typical form it can grow into a tree up to 30 m tall. The trunk and branches are usually clad in long, leathery strips of bark, rather than the short, papery, rather flaky brown bark typical of the tree forms of mānuka. Kānuka leaves lack the sharp tip of mānuka. The flowers are also less showy.