January, 1938 The Queensland Naturalist 
67 
Bailey’s “Queensland Flora,” Polystichum constituted a 
subdivision of the comprehensive genus Aspidium. It was 
separated as a genus by Roth in 1799. The genus is 
readily distinguishable from its nearest relative, Dryop- 
teris, by the very unequal-sided pinnules, the more coria- 
ceous and rigid texture and the usually scaly stipes. 
Polystichum is a large genus comprising over a 
hundred species (108 according to Christensen’s Index 
Filicum), which are widely distributed over all the con- 
tinents of the world. The Australian species number only 
six, five of which occur in Queensland, the remaining one 
(P. hispidum) being confined in Australia to New South 
Wales, Victoria and Tasmania, One of the species 
(P. fragile ) is restricted to North Queensland in the 
vicinity of Ravenshoe. New South Wales also records 
five species, including four of the Queensland ones and 
P. hispidum ; Victoria has three species — P. adiantiforme, 
P. aculeatum and P. hispidum , while South Australia has 
only one — P. aculeatum. 
Ferns of this genus are popularly referred to as 
Shield Ferns. 
GENERIC DESCRIPTION. 
Sori roundish, dorsal or terminal on the veins. In- 
dusium round and peltate, or rarely reniform and at- 
tached by the sinus. 
Rhizome creeping or erect. Stipes not articulate 
to the rhizome, usually more or less densely clothed with 
scales at least at the base. Fronds tufted or distant, 
2-4-pinnate in Australian species, coriaceous and rigid, 
the leaflets unequal-sided, either with the lower side less 
developed or the upper base broadly truncate and the 
lower obliquely cut away; margins often spinulose; veins 
free. 
KEY TO THE SPECIES. 
A. — Margins of the fronds acutely toothed or spinulose. 
B. — Fronds 2-3-pinnate, ultimate seg- 
ments broad. Rhachis (except 
for the scales) smooth or 
minutely scabrous. 
C. — Stipes and rhachis coarsely 
scaly and fibrillose, Seg- 
ments acutely toothed .... 1. aculeatum 
CC. — Stipes and rhachis more or 
less scaly with fine narrow 
