July in the hills with Chris Horne and Barbara Mitcalfe
Dysoxylum spectabile, kohekohe
Some club members have been treated to spectacular displays of kohekohe trees in flower this winter. Sheena Hudson reported festoons of flowers in Colonial Knob Scenic Reserve, where tūī and waxeyes were vying for the nectar. Lois Hope described as “wonderful” the display of flowers in Birdwood Street Reserve, Karori.
Dysoxylum means “bad wood”, referring to the bad odour and taste of the bark of some species of this genus; spectabile means “spectacular, eye-catching” – appropriate for a tree that at the peak of flowering can be a simply stunning sight.
The genus Dysoxylum is in the Meliaceae family, which comprises mostly tropical trees and shrubs in about 80 genera and 800 species, including mahogany. Kohekohe, a NZ endemic species, occurs in coastal to lowland forest in the North Island, and the northeastern tip of the South Island. It can grow to c.15 m tall, with a columnar trunk up to c. 1 m diameter, with pale-grey bark, and stout branches.
The leaves are compound, comprising a terminal leaflet, and 3 - 4 pairs of glossy, leathery, mostly opposite, leaflets. These range from 5 – 20 cm long, and 2 – 8 cm wide, the result often being an impressively large leaf. The flowers are up to 3 cm diameter, with waxy, greenish-white petals, and a subtle, spicy perfume. The flowering stems, up to 40 cm long, are usually cauliferous, i.e. growing straight out of the trunk, sometimes right down at ground level. The capsules containing the seeds are about 25 mm diameter, looking rather like bunches of green grapes. Look out for them from now until August – they will persist for about fifteen months, splitting open to reveal two seeds in each cell, with a fleshy, scarlet cover. Kohekohe may not flower each winter, because they are 'mast' flowerers, i.e. after a particularly abundant flowering, they may not flower heavily for a year or more.
Kohekohe forest used to form extensive tracts in warm, damp sites, most of which have been cleared for housing and farming. The remnants have been severely damaged by possums, but in reserves where Greater Wellington Regional Council, city and district councils, have been poisoning possums, these forests have been restored, e.g. Hemi Matenga Reserve in Waikanae, Raumati Escarpment Reserve, Whareroa Farm Park, Khandallah Park, Huntleigh Park, Otari-Wilton’s Bush, and Wellington Botanic Garden contain areas of kohekohe forest.
Among its rongoa uses, some Māori boil kohekohe bark to make a tonic, and the boiled leaves are used make a poultice for boils, wounds, skin disorders and inflammation. Early Pākeha settlers in Northland made culinary use of the leaves by using them as a substitute for yeast, instead of hops, when making bread