110 BRITISH FERNS. 
ferns, of which Recurvum, Multiflorum, Glandulosum, 
Spinosum, Uliginosum and Callipteris are constituent 
parts. Many very able botanists still regard Spinosum, 
__ Uliginosum and Callipteris as varieties of one species, 
an opinion which it is not necessary to controvert, 
because we shall find it impossible to arrive at a 
satisfactory conclusion; the great requirement seems 
to me to gain a knowledge of the objects, and to leave 
to such philosophical writers as Mr. Darwin to assign 
to each the rank it ought to hold in the general 
stem. 
_ The caudex of Callipteris is very stout, and gra- 
dually increases in length as the plant increases in 
age, occasionally emitting a lateral branch, which in 
due time also becomes branched, so that an old plant 
is sometimes possessed of a very extensive and com- 
S plicated caudex, which throws up fronds from all its 
___ extremities. The base of the stalk of each frond, 
instead of decaying with the frond, retains its sap and 
vigour for many years, and in time assumes so nearly 
the appearance of the caudex itself that it is difficult 
to separate them. The fronds are but few in each 
tuft, and rise from the crown of each growing branch 
of the caudex; they appear in May, and remain green 
until near the end of the year: the form of the young 
‘Unexpanded frond somewhat resembles that of the 
Mountain Fern: the general character is circinate, 
‘but the pinne are perfectly flat. The stalk is of 
