98 
KATHY M. NICHOLS, J. H. BROWNE AND R. F. PARSONS 
Fig. 6. Eighteen-week-old seedlings of (A) Marsdenia 
australis , showing tuberous taproot and (B) 
Rhyncharrhena linearis with non-tuberous roots. Scale 
= 20 mm. 
shrubs and mallee eucalypts, with Marsdenia 
twining up eucalypt trunks of up to 90 mm diam¬ 
eter and to heights of at least 4 m. Where Mars¬ 
denia and Rhyncharrhena occurred in Callitris- 
Casuarina woodlands, we found them on shrubs 
but not on the trees. While there are records 
from large trees (e.g. photograph of Rhynchar¬ 
rhena on Calliiris , Victorian reference set, 
National Herbarium of Victoria), it may be that 
such trees were climbed many years previously 
when they had thinner stems. 
Internode lengths were shorter for unsup¬ 
ported lianes than supported ones and were gen¬ 
erally shorter for Marsdenia than for Rhynchar¬ 
rhena. It was common to find small, unsup¬ 
ported shoots scattered in the vicinity of large, 
supported plants in both species. 
Fig. 7. Marsdenia australis. A plait of five stems 35 
mm in diameter at site 5; the plant extends from the 
soil surface to the crown of a mallee species of Eucalyp¬ 
tus (stem visible in background). 
Roots andperennation. Parts of site 1 were exca¬ 
vated on 26-27 June 1990 to determine whether 
small, unsupported shoots were suckers or seed¬ 
lings, and simultaneously to describe root 
systems. 
Excavation of one adult Marsdenia plant and 
ten small shoots in an area of 2 x 1.5 m showed 
that all ten were suckers. Tissue sections showed 
that these arose from lateral roots. The suckers 
were from roots at depths of 100 mm to more 
than 500 mm below the surface and with diam¬ 
eters of 5 to 18 mm (Fig. 8A-C). They can occur 
more than 2 m from the parent plant. 
Marsdenia has perennial tuberous roots, both 
laterals and tap-roots, the laterals up to 0.5 m 
long and 25 mm in diameter (Fig. 8A-C) and 
thus appreciably larger than those recorded in 
this species by Pate & Dixon (1982). The tuber¬ 
ous roots contain many large starch grains up to 
10 pm in diameter; the stems have fewer, 
smaller grains (2.5 pm diameter). Copious 
branching leads to a complex system of tuberous 
