|Author: ||W. Harris|
|Keywords: ||Cabbage tree, New Zealand, plant form, cold hardiness, conservation|
Cordyline australis (New Zealand cabbage tree) is widely grown in temperate climates as a garden and landscape subject and as a tub plant.
Diversification of its use as an ornamental has been based on discoveries of plants with unusual leaf colours and growth forms, and hybridization with the other New Zealand Cordyline species.
A systematic assessment of the genetic variation of wild populations of C. australis began in 1994 with measurements of the phenotypes and collection of seed of trees in 29 natural stands located over 12° of latitude.
Progeny of these stands have been cultivated under uniform garden conditions at Auckland (36° 53´ S), Christchurch (43° 38´ S), and Dunedin (45° 51´ S) and their growth and phenology recorded.
This has shown variation of leaf characteristics, tree habit, growth rate, susceptibility to low temperature damage, and onset of flowering, much of which is related to the latitude of origin of the populations.
As well unusual plants within populations provide material of ornamental interest.
The study relates to the use of C. australis in ecological restoration plantings and threats to conservation of the genetic integrity of wild stands.
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