THE COMMON HART'S-TONGUE FERN. 141 
Caudex short, thick, tufted, often decumbent, scaly at the crown. 
Scales lanceolate-acuminate, pale purplish-brown, shining, finely 
reticulate-venose. Fibres short, branched, numerous, dark brown. 
Vernation circinate. 
Stipes averaging about one-third the length of the frond, but 
varying from about one-fourth to one-half its entire length, usually 
clothed with pale tawny contorted subulate scales, sometimes smooth, 
purplish-brown, darkest at the base; terminal, and adherent to the 
eaudex. Rachis, or more correctly midrib, stout, scaly behind when 
young, often dark-coloured below. 
Fronds from about four inches to two feet or upwards in length, 
narrow elongate-lanceolate, or broadly linear, or oblong strap-shaped, 
plane, fleshy or coriaceous, deep rich green; they are normally 
entire or but slightly sinuous on the margin, the apex more or less 
attenuated terminating in an acute point, and the base cordate. 
The varieties deviate in unnumbered forms, by the laceration or 
undulation of the margin, by the production of an excurrent mem- 
brane from either surface, by the multifid dilatation of the apex, by 
the branching (once or repeatedly) of the stipes and midrib, by the 
loss of the lobes forming the heart-shaped base or their acute pro- 
longation so as to resemble the barbs of an arrow, and by the 
arrest of longitudinal development. Sometimes fronds are produced, 
which are reduced to mere awl-shaped bodies, representing the stipes 
and costa, everything else being suppressed. 
Venation parallel-forked : that is, the veins which spring from the 
stout costa or midrib, which is scaly behind when young, and often 
dark-coloured in the lower part, are one two or three times forked 
near their base; and the veinlets or branches thus produced are 
parallel, extending side by side obliquely almost to the margin, 
where they terminate in club-shaped apices. In the cordately 
enlarged base of the frond, the furcations are more numerous. 
Fructification dispersed over the back of the frond, most abundant 
upwards; sometimes borne on the upper surface. Sort linear, 
oblique, unequal in length, double or twin, that is, growing in pairs, 
the two contiguous parallel lines of spore-cases borne on the poste- 
rior and anterior veinlets of adjacent fascicles of veins, becoming 
confluent into one broad linear mass, forming a double sorus. Indu- 

