Polypodium Calcareum, J. E. Smith. 
Gymnocarpium Robertianum, Newman. 
RIGID THREE-BRANCHED POLYPODY. 
Root — Fibrous and black ; rhizome black and creeping, 
from which the fronds spring at intervals. 
Frond — Erect, rigid, subternate, rhomboid-triangular 
(the base, or outline below the broadest diameter, being in 
the majority of Matlock specimens, a little longer than 
the sides ; one measuring 22 inches, is at the base of the 
frond 11 J inches wide, while the sides are only 9J inches 
deep), three-branched : basal branches, lower half pinnate, 
upper half pinnatifid ; the upper branch pinnate, apices 
acute. 
Stipes — About two-thirds the length of the frond, much 
firmer and stronger than in P. Dvyopteris, sparingly covered 
with scales, but grey, as well as the frond, with minute 
glands. 
Pinnae — Triangular-lanceolate, pinnatifid, the lower pinnae 
and pinnules being longer than the upper. 
Pinnules — Oblong, obtuse, somewhat serrated. 
Venation — Costae sinuous, lateral veins simple and 
branched. 
Fructification — Clusters of capsules, circular, sub- 
marginal. 
Habitat — Rocky places, in limestone districts, upon deep 
loose stones: thrives in sunshine. Once locally abundant 
about Matlock, Buxton, Miller’s Dale, &c. 
