Groom: Flood tolerance of two Banksia species 
tissues or presence of hypertrophied lenticels (Kozlowski 
1997), although these were not examined. 
Although flood survival is important for B. littoralis 
seedlings, flooding events are episodic in nature and 
restricted to winter and spring months. Surviving the 
annual summer drought may be more important for 
seedling recruitment. Physiological data suggests that B. 
littoralis is inherently less water-use efficient (assuming 
Ops„/g 5 « photosynthesis/water transpired) than xeric 
congeners, and is similar to results obtained for B. 
littoralis under drought conditions (Groom 2002). 
Seedlings of Banksia littoralis can be classified as 'water 
spenders' in response to flooding (this paper) and 
gradual summer drought (Groom 2002). By maintaining 
a relatively high rate of stomatal conductance (0.1-0.2 
mol nr 2 s* 1 ; 50-75% of well-watered plants) during 
flooding, B. littoralis was able to support sufficient 
photosynthetic activity to allow shoot growth to occur at 
a rate similar to, or greater than, well-watered plants. 
Banksia littoralis seedlings are able to maintain stomatal 
conductance between 0.2-0.3 mol nr 2 s' 1 until volumetric 
soil moisture contents drop below 2% (Groom 2002). For 
B. littoralis seedlings, an overall higher as compared to 
more xeric congeners, may be viewed as a flood survival 
technique and/or a response to year-round access to 
reliable water sources. 
The lack of post-flooding physiological recovery and 
the greater sensitivity of B. prionotes to waterlogging is 
not surprising considering this species characteristically 
occurs on well-drained, sandy soils (Taylor & Hopper 
1988). Banksia littoralis inhabits winter-wet locations and 
wetland fringes, tolerating up to 104 days of water 
inundation (this study), without detrimental impacts on 
leaf ecophysiology once waterlogging ceased. This 
enables B. littoralis seedlings to survive exceptionally wet 
winter-spring months when flooding events are more 
likely to occur. Banksia littoralis seedlings also survived 
and sustained growth after being fully submerged for 54 
days, although in this experiment the leaves tended to 
discolour and were prone to epiphytic algae growth. 
Although the impact of submergence on seedling 
recruitment in B. littoralis has yet to be quantified, species 
that grow well when waterlogged or grown in flood 
conditions are unlikely to do as well when subjected to 
extensive periods of submergence (Parolin 2001; 
Mauchamp & Methy 2004). 
Acknowledgments: This research was supported by a Postdoctoral 
Research Fellowship Scheme funded by the Ministry for Commerce and 
Trade, Western Australia. Special thanks to Ray Froend and colleagues 
from the Centre for Ecosystem Management, Edith Cowan University for 
their support and financial assistance. This paper was written whilst the 
author was a research fellow at the University of Western Sydney. 
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