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Telopea 8 ( 4 ): 2000 
Cytology and karyotype (Barlow 1959,1983) support several of the fruit, bracteole and 
samara-based subdivisions in the family (Johnson & Wilson 1989). There are also 
studies detailing pollen (Kershaw 1970), anatomy (Williams & Metcalf 1985), stem 
morphology (Torrey & Berg 1988), 17 stem, tooth and stomate characters in 
Gymnostomci and the other genera in the family, especially as fossils (Scriven & 
Christophel 1990, Scriven & Hill 1995), and 22 vegetative, stomatal and reproductive 
characters for extant genera (Dilcher et al. 1990). 
De Candolle (1846) stressed the taxonomic value of seedling morphology. Seedling 
characters were deemed useful in angiosperm classification (de Vogel 1980), especially 
if adult material was difficult to obtain or the plants had long life cycles. Clifford (1991) 
and Li and Hsieh (1997) observed that members of the same genus often have similar 
seedling characteristics. Leonard (1957) advocated that there should be only one type 
of seedling in a 'good' genus, and that genera should differ significantly in their 
seedling morphology. Nevertheless, Weberling and Leenhouts (1966) proposed that 
genera should not necessarily be divided on seedling variation. Conran et al. (1997) 
found that for some taxa, seedling characters were more useful at subgeneric and 
sectional levels, rather than generic. 
Boodle and Worsdell (1894), commenting on the higher level relationships of 
Casmrim, included seedling information, and Duke (1965), Burger (1972), Torrey 
(1983) and Boland et al. (1984) described or illustrated seedling morphology for a 
number of Casuarinaceae species. Their listed characteristics included root colour; 
lateral root abundance; hypocotyl position against the soil; hypocotyl colour and 
length; cotyledon shape, index, attachment, apex and base shape, adaxial and abaxial 
colour, texture and indumentum; epicotyl length (first internode above the hypocotyl), 
stem straightness; number of leaves (teeth) per whorl and tooth shape, colour and 
length. Unfortunately data were provided for few taxa, and generally without 
systematic sampling within the family. 
This present study investigates seedling morphology in the Casuarinaceae, comparing 
the results against the current classification of Wilson and Johnson (1989) and the adult 
morphology-based studies of Dilcher et al. (1990) and Scriven and Hill (1995) to 
examine the distribution and usefulness of seedling features in the family. 
Materials and methods 
Seeds from 123 provenances representing eight Casmrim and 34 Allocasuarina taxa 
were obtained from various sources detailed previously in Hwang and Conran (1991). 
The seeds were soaked overnight under running tap water, and germinated on wet 
cotton wool in an unheated glass house (temperature range 10-35°C) under natural 
lighting. Casuarinaceae seeds germinate readily, mostly in 15-30 days at 20-25°C 
(Elliot & Jones 1982), and most species benefit from daily exposure to light during 
germination (Turnbull & Martensz 1982). Pre-soaking the seeds in water for 24 hours 
improves germination rates (Kuo 1984). A summary of the germination features for 
Australian Casmrim and Allocasuarina species is given in Hwang and Conran (1991). 
Germinated seeds were planted 40 mm apart and 10 mm deep in drained plastic trays 
with an unfertilised, unsterilised 2:2:1:1 soil mixture of coarse river sand, fine pine 
bark, red mountain soil and grey sandy loam. There were 15 columns x 7 rows per tray, 
with 21 seedlings per provenance. Average seedling survival per provenance was 18.8 
(range 1 to 21), and the seedlings were grown and observed for 3 months with daily 
watering. With the exception of ephemeral or developmental characters, data were 
recorded from three month old seedlings and scored as the average of all surviving 
seedlings for each taxon. Data for Casmrim junghuhniana Miq. were taken from the 
