10 
DR R. C. DAYIE ON 
The Leaf-Trace and Pinna-Trace of Leptochilus guianensis (Aublet) C. Chr. 
Another Fern of the rain-forest on the Serra da Carioca to show the combination- 
type of pinna-trace is Leptochilus guianensis (Aublet) C. Chr. This is a climbing 
Fern, with a long and wiry stem and rather short, simply pinnate leaves of the 
Stenochlsena type. The leaf-trace consists of five strands (text-fig. 4 a ) — two on the 
bed 
Text-fig. 4. 
adaxial, three on the abaxial side of the petiole. The adaxial strands are, in the 
lower portion of the petiole, unhooked. But near the insertion of the first pinnae 
their edges loosen out and become hooked (text-fig. 4 6, d). Then the hook separates 
off, leaving one tracheide behind, close to the inner face of the parent strand, with 
which it presently coalesces. Meanwhile the abaxial strand nearest to the pinna to 
be supplied has extended its margin towards the pinna. There is no development of 
a hook on this strand ; its margin is simply nipped off (text-fig. 4c) and moves out 
to the pinna with the arc derived from the adaxial strand (text-fig. 4 d). 
The Leaf-Trace and Pinna-Trace of Polystichum adiantiforme (Forst.) J. Sm. 
Polystichum adiantiforme (Forst.) J. Sm. is common on the loose sand of the 
Ipomsea biloba zone on the restingas and on the tops of the cliffs which intervene 
between the restingas. It has a leaf about a foot long with a firm petiole and 
repeatedly-divided leathery pinnse. The leaf-trace is represented in text-fig. 5. 
Text-fig. 5. 
There are two prominent hooked strands on the adaxial side of the petiole and a 
varying number of small strands on the abaxial curve. Below the first pinna one of 
the hooked adaxial strands extends its back towards the pinna, while it stretches out 
its abaxial end as a tongue towards the abaxial curve series (text-fig. 5a). At the 
same time the corner strands of the abaxial curve series also move out towards 
the pinna, dividing and fusing repeatedly among themselves as they do so (text- 
fig. 56, c). The tongue stretched abaxially from the adaxial strand is nipped off as 
a small strand which sometimes takes its place with those which reform the abaxial 
curve. The pinna-trace is thus composed partly of the back of the hook of an 
adaxial strand, partly of strands derived from the series on the abaxial curve of the 
leaf-trace. The process of supplying the pinna-traces to the subsequent pinnse is 
