10 GEELONG NATURALIST Vol. 37 No.1 May 2001 
Growth rates of flower-spikes on Austral Grasstrees 
.. Jo Heatlie and Trevor Pescott 
11 Coorumby Avenue. Clifton Springs, 3222 & 14 Victoria Terrace, Belmont, 3216. 
Flower spike length 
Budded 
section 
Un-budded 
stem 
Crown height 
Ground 
Figure 1 
Introduction 
The Drysdale Basin is a small, Council-managed block of public land on the Bellarine Peninsula. (Heatlie, J. Geelong 
Naturalist Vol. 36 No. 4) 
Early in August 2000, a group of Austral Grasstrees Xanthorrhoea australis growing at the Basin began producing 
flower-spikes. 
Grasstrees are renowned for flowering after fires, as typified by the large number that did so off Butchers Road in the 
Brisbane Ranges following burning, and in other places from time to time. But they will also flower without fire, as was 
the case at Drysdale Basin. 
Flower-spike development 
After the flower-spikes were first noticed, one of us (JH) measured them each week, 4.9.00 excepted. The 
measurements taken were of the un-budded stem and the budded section (see Figure 1 above); however, due to the 
irregularity of the point where the buds begin, it is better to consider the length of the overall spike. The heights of the 
plants to the crown were also recorded. 
Table 1: Growth measurements (lengths of flower spikes) 
Plant No. 8 Average Average 
length (n=6) increase 
Height to crown 
7.8.00 
14.8.00 
21.8.00 
28.8.00 
4.9.00 
11.9.00 
18.9.00 
25.9.00 
2.10.00 
9.10.00 
16.10.00 
24.10.00 
Notes: Measurements are in cm. *Asterisked individuals not included in averages. 
