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INDUSIUM (PI. Indusia). The membranous skin covering the 
sori. 
INVOLUCRE. The indusium ; used more especially when it 
surrounds the sorus like a cup. 
LANCEOLATE. Lance-shaped; broadest in the middle and 
LAX. 
LINEAR. 
tapering to the ends. 
Soft and flabby. 
Narrow; of the same breadth throughout 
except at the extremities. 
LINEAR-LANCEOLATE. Of a very narrow lance-shape. 
LOBE. A rounded division of a leaf. 
MEMBRANOUS. Thin and semi-transparent; like membrane. 
MID-RIB. 
MID-VEIN. 
The rachis. 
The central vein of a leaf. 
OBTUSE. 
OVATE. 
Blunt at the end. 
Egg-shaped, with the lower end the broadest. 
PELTATE. 
Target-shaped, with the stalk inserted under¬ 
neath near the centre; like a mushroom. 
PINNA5 (Sing. Pinna). The primary separate divisions of the 
leaf. 
PINNATE. 
PINNATIFID. 
PINNULES. 
Divided into separate, distinct leaflets. 
Cleft nearly but not quite down to the mid-rib. 
The ultimate or final separate leaflets of a 
PROSTRATE. 
compound frond. 
Lying flat and spreading on the ground. 
RACHIS. 
The main stem, from where it enters the leaf to 
RECURVED. 
reflexed. 
RENIFORM. 
REVOLUTE. 
RHIZOMA. 
the apex. 
Bent downwards. 
Bent backwards. 
Kidney-shaped. 
Rolled backwards. 
The creeping stem, running along, or partly 
under the ground. 
SEGMENT. 
SERRATED. 
A division of the frond. 
Notched. 
