
THE BRITISH FERNS. 
The erect stems of Ferns vary much in bulk, and in some species 
branch freely, producing many tufted crowns, but in other species 
they are very rarely at all divided. It is no doubt partly to this 
tendency to development only from the terminal bud, that the eleva- 
tion acquired by the stems of tree Ferns is due. 
Various terms are employed to express the peculiarities which 
occur in this caudiciform stem. Thus when it is simple and erect, 
and acquires an elevation of about two or three feet or upwards, it is 
said to be arborescent. The dwarfer forms of upright-growing simple 
stems are generally described as erect, the. fact of their being dwarf 
and not arborescent, being understood. The dwarf caudiciform 
stems are not, however, always erect; they sometimes grow hori- 
zontally along the surface of the ground, and are then decumbent, 
or if much elongated, with the fronds distantly placed, creeping or 
scandent. The decumbent form of caudex would be well repre- 
sented by a stem of Lastrea Filix-mas which had fallen aside to a 
horizontal position; while the creeping caudex is illustrated by 
that of Lastrea Thelypteris, or Pteris aquilina, the latter not only 
extending to a considerable distance, but penetrating to a con- 
siderable depth. The wiry stems of Trichomanes, and the fine 
thread-like stems of Hymenophyllum, seem to be rather modi- 
fications of the creeping caudex, than rhizomiform stems as they 
are often considered. When the stem is very short and branched 
so that several crowns are formed in a cluster, it is said to be tufted; 
this is illustrated in the Cystopteris fragilis. 
The rhizome is, in almost all cases, of creeping or scandent habit, 
and is very frequently epiphytal. In some exotic genera, as for ex- 
ample in Oleandra, it is, however, erect, and produces roots from its 
lower parts, on all sides indifferently. In this form of stem, the bases 
of the fronds are not continuous with the axis, as in the case of the 
caudex, but they have a natural joining or articulation at which 
they separate spontaneously when their functions are completed, 

