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 — 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 11J inches 
wide, while the sides are only 9| 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. Dryopteris , sparingly 
covered with scales. 
Pinnae — Triangular-lanceolate, pinnatifid, the lower pinnae 
and pinnules being longer than the upper. 
Pinnules — Oblong, obtuse, somewhat serrated. 
Venation — Midvein sinuous, lateral veins simple and 
branched. 
Fructification — Circular clusters of capsules, marginal 
when in perfection. 
Habitat — Rocky places, in limestone districts, upon deep 
loose stones: thrives in sunshine. Locally abundant about 
Matlock, Buxton, Miller’s Dale, &c. 
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