110 
KATHY M. NICHOLS, J. H. BROWNE AND R. F. PARSONS 
only plants which appear to survive are those 
which have the stem closely pressed to the bark 
of a tree or are growing up through a groove in 
the bark” (W. E. Mulham, personal communi¬ 
cation). In central Australia Marsdenia is notice¬ 
ably rarer in the area of highest rabbit numbers, 
namely the south west corner where rabbit graz¬ 
ing has apparentlv severely reduced the species 
(Latz 1982). 
A similar case of a marked grazing effect on a 
liane concerns the eastern Victorian Parsonsia 
brownii in the closely related family Apocyna- 
ceae. P. brownii is especially palatable to walla¬ 
bies and normally only scattered plants of it can 
be found. Where wallabies are absent, however, 
as in some very small remnants of native veg¬ 
etation or in reserves surrounded by suburbs, 
dense stands of P. brownii develop (Ashton 
1989; N. H. Scarlett, personal communication). 
The New Zealand P. heterophylla is especially 
palatable to a browsing bird (Clout & Hay 
1989) . 
DISPERSAL 
Both Marsdenia and Rhyncharrhena have typi¬ 
cal asclepiad seeds with a terminal coma of long 
hairs. In Asclepias syriaca, these hairs allow 
wind dispersal at distances of up to 150 m and 
further (Morse & Schmitt 1985), and in Araujia 
sericofera such dispersal allows the species “to 
arrive in almost every Auckland garden” (Esler 
1988). There is no evidence that Marsdenia or 
Rhyncharrhena seeds are predated by birds or 
ants. 
CONSERVATION 
While not threatened Australia-wide, both 
Marsdenia and Rhyncharrhena are now re¬ 
garded as vulnerable in Victoria (Gullan et al. 
1990) . The apparent severe decline under graz¬ 
ing, the absence of seedling establishment, the 
lack of information on the lifespan of the re¬ 
maining adult plants and the very small number 
of adults in biological reserves are all causes for 
concern. Although Rhyncharrhena is recorded 
from a total of four Victorian reserves (Beaugle- 
hole 1979), in each case only a few plants are 
present (A. C. Beauglehole and J. N. Macfarlane, 
personal communications). Marsdenia is a very 
similar case, being regarded even in 1937 as 
“likely to become extinct” (Zimmer 1946). 
Conservation work so far has involved fencing 
small patches of both species at Hattah-Kulkyne 
National Park (site 4) and Pink Lakes State Park 
(site 6), and at the latter providing small tree 
guards about 300 mm high for Rhyncharrhena 
suckers. We only saw fruiting of either species 
occur when the plants were climbing in shrubs or 
trees; although increased shoot growth occurred 
when the tree guards were installed, no fruit was 
set. Grazing exclosures for the species should 
include long-lived trees or shrubs if possible; if 
none are present, it may be necessary to intro¬ 
duce them to make the exclosure worthwhile in 
the long-term. 
ETHNOBOTANY 
In central Australia Marsdenia and Rhyncharr¬ 
hena were important and favoured aboriginal 
foods, all parts being used except the stems and 
fine roots. The aborigines were aware that a diet 
containing a high proportion of Rhyncharrhena 
caused their children to lose weight (Latz 1982). 
The ground-up seeds of both species are reputed 
to have been used as an oral contraceptive 
(Lassak & McCarthy 1983). 
The immature fruits of Marsdenia are so 
delicious that the species may be worthwhile 
cultivating (Cherikoff & Isaacs, no date; V. 
Cherikoff, personal communication). 
ACKNOWLEDGEMENTS 
We thank P. K. Latz, J. N. Macfarlane and 
I. Sluiter for unpublished data and gifts of seed, 
F. J. Daniels and I. A. Staff for advice on plant 
anatomy, C. Lloyd for help with statistical analy¬ 
sis and the National Parks and Wildlife Division 
for a research permit. M. J. Bartley provided 
considerable assistance throughout. P. K. Latz 
kindly provided criticism of the manuscript. 
REFERENCES 
Ashton, D. H., 1989. Restore Sherbrooke’s ecological 
balance. Letter to the editor, The Age , Mel¬ 
bourne, 13 January 1989. 
Australian Division of National Mapping, 1986. 
Atlas of Australian Resources, 3rd series, vol. 4, 
Climate. Division of National Mapping, Can¬ 
berra. 
Badaway, N. S., 1982. Soils of north-western Vic¬ 
toria, their characteristics and significance to 
local agriculture. Victorian Department of 
Agriculture, Technical Report Series No. 55, 
Beadle, N. C. W., 1981. The Vegetation of Australia. 
Cambridge University Press. 
Beauglehole, A. C., 1979. The Distribution and 
Conservation of Native Vascular Plants in the 
