ip. AMERICAN FERN JOURNAL 
It is rolled in a coil in the bud phase; (2) as it unrolls 
the apex continues to grow; this power of more or 
less indefinite growth is possessed most remarkably by 
_Lygodium and the Gleicheniacez. Campbell refers 
to leaves of Lygodiu um which reach a length of one 
hundred feet, and in the Gleicheniacee the leaf apex 
may continue to unroll for several seasons; (3) fern 
leaves bear sporangia on the back. 
Ferns then are pteridophytes with leaves of the type 
just described. 
Fern allies should be, as the word ‘* allies ” implies, re- 
: Anted to ferns. Relationship, as ordinarily determined 
Ce in such ¢ eases, depends on (a) similarity of structure, and 
a a own by ly ils 
: Pacers to structure, lycope 
called © fern allies,” are ne 
gical aia: oe pra 
= lycopods, and ecuiinetes ‘eon’ any spotter te 
the earliest horizons in which fossils of vascular plants 
cs are found these — sue oceur, and differ in the 
‘cae 
