ieee eee 
OLD-FASHIONED FERNS 257 
“veins”) present different patterns, sometimes being 
parallel to one another or divergent (veins “free’’), or 
uniting here and there in a netted fashion (veins 
“reticulated’’). 
457. Since the sporophytes of ferns are long-lived 
they delay the formation of their spores, this sometimes 
not taking place for a few years (or many years in tree 
ferns). In the more primitive ferns the spores develop 
from internal cells (as in Anthoceros of the Bryophyta), 
but in the higher forms they are produced in superficial 
sporangia. 
458. On account of the dominance of the sporophyte 
its structure has been emphasized in the systematic 
classification of the ferns, although some consideration 
has latterly been given to gametophyte characters. 
About 3800 species of Ferns have been described, and 
they are widely distributed throughout warm and tem- 
perate’ regions. 
459. There are two classes of Ferns, as follows: 
1. Old-fashioned Ferns (Class EusPoRANGIATAE) in which 
the spores develop from internal cells. 
( 
Fie. 133.—Ophioglossum. Fie. 134.—Angiopteris 
(Marattiales); develop- 
ment of sporangia. 
460. Here are the Adder-tongues (Order Opuio- 
GLOSSALES) by many botanists regarded as the lowest of 
the Ferns, and not very distantly related to Anthoceros 
of the preceding phylum. Here too are placed the 
17 . 
