104 
KATHY M. NICHOLS, J. H. BROWNE AND R. F. PARSONS 
Fig. 12. A, longitudinal section through a stem node of 
Rhyncharrhena linearis , showing stem (S), petiole (P), 
an axillary bud (A) and a foliar gland (G) on the base of 
the opposite petiole. Scale = 0.2 mm. B, transverse 
section through a similar node, showing stem (S), axil¬ 
lary bud (A) and foliar gland stalk (G). The petiole (P), 
cut obliquely, has a crescent-shaped vascular strand 
(V) and accessory bundles (B). Note the radial arrange¬ 
ment of cells in the gland. Scale = 0.2 mm. 
In summary, there are striking differences in 
seedling growth between the two species. The 
extra dry matter produced by Marsdenia is used 
for production of tuberous roots. Despite very 
similar shoot dry weights, Marsdenia produces 
thicker stems, larger leaves and a more rigid, 
erect shoot while Rhyncharrhena produces 
much longer, thinner shoots (Fig. 15). The 
reasons for these differences are obscure given 
the similarity between the two species in be¬ 
haviour and habitat in the field. 
The cessation of growth of both species at 
16/14°C is like the behaviour of C 4 grasses at 
such temperatures (Evans et al. 1964). Given 
Time (days) 
Fig. 13. Germination rate of Marsdenia australis and 
Rhyncharrhena linearis at various temperature re¬ 
gimes for seed 19 mo old. Open circles = Rhyncharr¬ 
hena at 25/15°C, open squares = Rhyncharrhena at 
16/14°C. Closed triangles, circles and squares = Mars¬ 
denia at 30/20°C, 25/15°C and 16/14°C respectively. 
Fig. 14. Germinability of Marsdenia australis seeds of 
various ages at 25/15°C. 
that the mean daily maximum temperature in 
June is about 16°C, the data suggest that little or 
no growth will occur in winter in the field. This is 
discussed further below'. 
These unsupported seedlings bowed over and 
grew more-or-less horizontally once they 
reached heights of 150 mm or so. We lack data 
