New Zealand Journal of Botany
abstracts
Genotypic variation of dead
leaf retention by Cordyline
australis (Lomandraceae)
populations and influence on trunk surface temperatures
Warwick Harris
Landcare Research
P.O. Box 69
Lincoln 8152, New Zealand
Present address: Lincoln Botanical, 16 Aylmers Valley Road, Akaroa
8161, New Zealand. Email: wdaharris@clear.net.nz
Ross E. Beever
Stephanie L. Parkes
Landcare Research
Private Bag 92710
Auckland, New Zealand
Tony McSeveny
Landcare Research
P.O. Box 69
Lincoln 8152, New Zealand
Abstract The
retention of dead leaves covering the trunks of 8-year-old trees of Cordyline
australis (cabbage tree, ti
kouka) was significantly different between 28 wild populations from a
12° latitudinal range in New Zealand when grown under uniform
garden conditions at Mt Albert, Auckland (36°53′S,
174°43′E) and Lincoln, Canterbury (43°38′S,
172°29′E). Particularly at Lincoln, trees of populations
originating from south of latitude 38°45′ mostly had trunks
fully covered by dead leaves at the time of observation. Temperatures
recorded at Lincoln at heights of 1.40 m and 0.05 m
showed that chilling on the trunk surface was reduced by a cover of
dead leaves, particularly at 0.05 m during radiation frosts.
This effect was separated from the shelter effect of the green leaf
tufts of trees and shelter between trees in the experimental
plantation. The adaptive function of the retention of dead leaves on
the trunk of C. australis
in frost-prone locations in southern New Zealand is considered with
reference to other possible adaptive functions.
Keywords Cordyline
australis; cabbage tree;
genotypic variation; dead leaf retention; latitudinal variation;
temperature insulation; adaptive functions; New Zealand
B04005; Received 13 February
2004; accepted 25 July 2004; Online publication date 9 December 2004
New Zealand Journal of Botany,
2004, Vol. 42: 833–845
0028–825X/04/4205–0833 © The Royal Society of New Zealand 2004
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