Hebe News – Article 2
LEPTOSPERMUM SCOPARIUM
When visiting New Zealand I was struck by the sight of whole hillsides of Leptospermum scoparium in flower. The bushes of small dark green leaves were covered in myriads of white flowers.
Uses
This shrub is known by New Zealanders as manuka, its Maori name. The wood, dark-red, hard and durable, was used by them to make paddles and spears, and as sticks in the construction of their whares (houses). Medicinally they applied an exudation to treat burns and scalds and used an infusion of the bark to treat dysentery. Captain Cook, in an account of his second voyage, recommended its use to make a tea. The wood was also used for fences and firewood, and a bunch of the twigs was used as a broom.
Taxonomy
There are 35 members of the genus Leptospermum. Most are Australian, with 3 in New Zealand and a few in New Caledonia and Malaysia. Leptospermum is a member of the myrtle family, Myrtaceae, which contains about 100 genera and about 3,000 species. This family consists of woody plants, chiefly shrubs and trees, and is found in mostly tropical and subtropical areas and Australasia. The most important member of the family is Eucalyptus, grown mostly for its timber but also medicinally to give oil of eucalyptus. The family also gives us cloves from Eugenia caryophyllata, allspice from Pimenta dioica, West Indian guava from Psidium guajava, ornamental shrubs such as the bottlebrush, Callistemon, the New Zealand Christmas Tree (or pohutukawa) Metrosideros excelsa, and the only European member, the myrtle. Leptospermum scoparium and Leptospermum ericoides have always been regarded as closely related. The former is a shrub or tree up to 13 ft (4 m) tall; the latter a shrub or tree up to 50 ft (15 m). In 1983 J Thompson has suggested, comparing floral (androecial) characteristics, the removal of Leptospermum ericoides to Kunzea. The third species Leptospermum sinclairii has also been moved to Kunzea.
Distribution
Leptospermum scoparium is commonly found throughout North Island, South Island and Stewart Island, also Chatham Island (where it is extremely rare). It grows in many habitats throughout lowland and subalpine areas. It is seen in heathlands, scrublands, open grass country, barren land and coastal areas, to the rear of the sand-dunes. It is an aggressive coloniser of recently cleared land, notoriously where forest has been burnt off. In the long term manuka acts as a nursery for slower growing trees and shrubs.
Cultivation
A shrub or small tree of variable habit, which can reach 12 ft (3.6 m) or more. The leaves are small, narrow and lance-shaped, and can be green or brown. The five petalled white flowers are up to 0.6 in (1.5 cm) across, superficially resembling a potentilla. Woody seed capsules are formed.
It was introduced into Britain in 1772, and was popular as a cool greenhouse plant due to the mass of white flowers borne in spring. It is tender in most of Britain, but is reliably hardy in south-west Britain, parts of Ireland and the west coast of Scotland. It does well on a light soil in a sunny position. I grow the Tasmanian Leptospermum lanigerum, which is totally hardy here in Macclesfield, although a very hard winter may reduce its flowering.
As magnificent as the white flowered manuka surely is, it is the pink and red flowered cultivars that hold centre stage. The first one was a rose-coloured form, discovered by Sir Frederick Chapman of Otago in 1889, at Signal Hill, on the outskirts of Dunedin. A rose-red form was discovered in 1898 at the Sandilands Sheep Station near Kaiapoi, Canterbury, South Island. In 1904 when William Nicholls, a wool and skin buyer of Belfast, Canterbury, was visiting the sheep station near Kaiapoi, he rediscovered a plant with rose-red flowers. He picked a sprig as a buttonhole and shortly after visited Nairn’s Nursery in Christchurch where Robert Nairn saw the sprig and asked for cutting material. The cuttings failed to root but some seed capsules on the sprig were saved and the seed sown. From these came 110 seedlings, only 7 of which flowered red or pink. Leptospermum scoparium ‘Nichollsii’ was selected from these. In 1908 Captain Arthur Dorrien-Smith, of Tresco in the Scilly Isles, took the plant to England. In 1912 the Reverend A T Boscawen showed it at the International Horticultural Exhibition at Chelsea, where it received a First Class Certificate and a cup for the finest plant exhibited. Plants were then sold at £25 each.
Breeding and selection continued, and in 1939 Dr W E Lammerts of the University of California crossed L. ‘Nichollsii’ with a double form to give 7 seedlings with single flowers. From these seeds was sown and about 1,000 seedlings were produced, of which many were double flowered. Amongst these were Leptospermum scoparium ‘Ruby Glow’ and Leptospermum scoparium ‘Red Damask’. Later, in the 1950s Duncan and Davies Nurseries, of New Plymouth, North Island, raised a series of dwarf cultivars named after New Zealand birds.
Description of Cultivars
Leptospermum scoparium ‘Boscawenii’ - Flowers white, 1 in (2.5 cm) across, with bright rose centres, raised by the Reverend A T Boscawen from New Zealand seed.
Leptospermum scoparium ‘Chapmanii’ - Flowers deep rosy-red, foliage bronze coloured, more hardy than L. ‘Nichollsii’.
Leptospermum scoparium ‘Keatleyi’ - Flowers soft pink, paler at the edge, about 1 in (2.5 cm) across. Discovered, before 1926, by Captain Keatley in the Hokianga district, North Island.
Leptospermum scoparium ‘Kiwi’ - Flowers Crimson, with a central black disk.
Leptospermum scoparium ‘Leonard Wilson’ - Flower white, double, found by Leonard Wilson on the Banks Peninsula.
Leptospermum scoparium ‘Nichollsii’ - Flowers crimson, with a darker centre, 0.6 in (1.5 cm) across, leaves bronzy-purple.
Leptospermum scoparium ‘Red Damask’ - Flowers deep cherry-red, double, 0.5 in (1.2 cm) across, red stems and bronzy foliage, dense habit, grows to 6 ft (1.8 m).
Tony Hayter
Registered Charity No 801398
