
INTRODUCTION. a 7 
two forms are those of a caudex and a rhizome. In the caudex or 
caudiciform stem, the fronds rise from the termination of the axis 
of growth, either in a single series, or in a kind of crowded whorl, 
so as to form a terminal crown. The young fronds in all cases 
spring from the inner side of those previously formed, their bases 
becoming united and adherent with the axis, so that the older part 
of the stem consists of a combination of the axis with the bases of 
the fronds developed from it. This manner of growth is exemplified 
in the common Male Fern, and in those species which form the 
tree Ferns of the tropical forests. In the rhizome or rhizomiform 
stem, the fronds, which are more or less seattered, are developed 
from the sides of the axis of growth, the point of which is apparently 
in advance of the last formed fronds; they are, moreover, developed 
from nodes formed on the rhizome, each node producing a single frond, 
which has an articulation or joining at or near to the base of its stipes, 
. at which point it eventually separates spontaneously. The common 
Polypody affords a good illustration of this mode of development. 
The caudiciform stem or caudex, is in numerous instances among 
the dwarf herbaceous species scarcely at all lengthened, but erect and. 
tufted, forming a ceespitose series of crowns, whence the fronds issue. 
Even among the species of herbaceous habit, however, the caudici- 
form stem occasionally in age becomes considerably elongated, and 
such instances, which may be found among our native species, afford 
an imperfect and pigmy illustration of the manner in which the 
trunks of the tropical tree Ferns are formed. This elongation of the 
older caudices may be observed frequently in the Osmunda regalis, 
which among our native Ferns is that which most frequently assumes 
this habit, being sometimes found with bare stems, a foot or more 
in height. The same tendency, though in a less degree, may be 
observed in very old plants of the Lastrea Filia-mas, Lastrea montana, 
. and Lastrea dilatata, and sometimes also in Athyrium Filix-femina, 
and Polystichum angulare. 

