Survey Of Plants Grown In N.Z.

Press, Volume CIII, Issue 30633, 26 December 1964, Page 16

Survey Of Plants Grown In N.Z.

A survey of flowering plants grown horticulturally in New Zealand has been started by Mr W. R. Sykes of the Botany Division. Department of Scientific and Industrial Research, Lincoln. The first section of the survey to be completed is on the family Bignoniaceae, which includes a number of vines and creepers, and trees such as the jacarandas and catalpas.

Mr Sykes thinks many more of the family of which in all about 650 species have been described, could be grown in New Zealand, although the family is mainly a tropical one and only relatively few are likely to be comfortable in most parts of the South Island. Mr Sykes has identified about 30 species in New Zealand, including half a dozen in the plains area of Canter-j bury and another dozen on the Port Hills. “I would like to see a huge arboretum established in New Zealand where new horticultural trees and shrubs could be tried out, and their suitability for growth under various New Zealand climates assessed,” Mr Sykes said. “The botanic gardens and New Zealand Forest Service do a good job in introducing new plants, but the potential is so great that they [can hardly more than touch the fringe of the problem.” Mr Sykes is trying to obtain a flowering specimen of Incarvillea delavayi, for the article or pamphlet about the family which he is preparing. The incarvilleas are an unusual type of plant for the family, being apparently a recent evolutionary development which has enabled the Bignoniaceae to reach high into the Himalayas. The

i incarvilleas die down each I winter, and in the spring pro|duce leaves direct from I ground level, followed by I short stalks bearing magnieent trumpet-shaped blooms. Mr Sykes thinks some of them would do very well in the South Island interior Delavayi has rosy-pink flowers, yellow on the inside | The catalpas are deciduous i north-temperate-zone trees with large simple leaves ! which get easily shredded by | the wind; the ones grown in New Zealand nearly all have white or pale yellow flowers spotted with purple and are in flower at present. Several abnormal forms with purplish or yellowish foliage are grown for their leaves. Two species (C. bignonioides and C. speciosa) are fairly common in Christchurch, and many other could probably be usefully grown here, says Mr Sykes. There are about 40 species of jacaranda, but only one— Jacaranda mimosifolia—has been seen by Mr Sykes in New Zealand. The finest specimens he has seen are in the Tauranga area. The tree is also fairly common elsewhere in the North Island and in Nelson. Mr Sykes does not hink this or other jacarandas would be likely to grow well in Canterbury, however. except perhaps in sheltered spots on Banks Peninsula.

Of the climbing members of the family, several arc well known in New Zealand. They include the Cape honeysuckle. Tecomaria capensis, probably the commonest hedge-plant in Auckland but too frost-tender for the plains area of Canterbury; the orange-flowered trumpet vine of the genus Campsis, common in Christchurch in a [hybrid variety but present too as the parent species; and the Port St. John creeper (Podranea ricasoliana), which grows on the Port Hills but is much commoner in the North Island. Mr Sykes believes many other climbing species of the Bignoniaceae would do well in New Zealand.

There is only one native New Zealand member of the family, and it is known from only one specimen, found on Great Island in the Three Kings group in 1945: moreover, it is endemic to New Zealand (not known elsewhere). Cuttings taken from the lone plant have been propagated successfully in Auckland and seed obtained iThe flower is creamy-white with orange anthers, and according to Mr Sykes is well [worth cultivating not only for its rarity but for aesthetic reasons.