a 
INTRODUCTION. 
more or less distant. In otlnir Perns, the proper stem may be considered as consisting chiefly 
of a growing point, from the centre of which the young fronds are developed, the bases of the 
older fronds forming the trunk, which is gradually decaying at one end and extending at the 
other ; the proper roots being protruded from between the bases of the older fronds. Stems of 
this structure, which is called the tufted mode of growth, assume either an erect or decumbent 
position, — in the former case sometimes elongating and becoming caudiciform, and in the latter 
becoming more or less creeping, though obviously ditfering in habit from the creeping stems 
first described. These distinct modes of development, Mr. Smith — the active Curator of the 
Eoyal Botanic Garden at Kew, and probably the best practical pteridologist in the kingdom — has 
lately proposed to adopt as the basis of a new method of classification — a method displaying 
much ingenuity and depth of observation, but which it is to be feared, if generally applied, 
woidd, practically, throw almost insuperable impediments in the way of the study and know- 
ledge of Perns, by the altered nomenclature which would be necessary ; and theoretically, is 
hardly to he admitted as having greater claim to precedence th;in the system which is founded 
on the natui’e and variations of the fi'uctification and venation, and which is now so extensively 
adopted. 
In the group of Marattiaceoe, the rhizome is usually thick and fleshy, and more or less 
globose. 
The fronds of Perns are those parts which have the appearance of leaves, and for general 
purposes may be considered as the equivalents of leaves, though there are some technical 
objections to their being regarded as leaves proper. The fronds consist of two parts — the 
stipes or stalk, and the leafy portion which it supports ; which latter is generally meant when 
the term frond is used descriptively. The stipes is either adherent to the stem, or there is at 
or near its base a natural joining or articulation, at which, when its functions are no longer in 
play, it separates spontaneously. When this latter structure occurs, the frond is said to he 
articulated with the stem. Sometimes the leafy parts of the frond are articidated in a similar 
way, hut this occurs less fi’equently. The continuation of the stipes through the leafy part 
in the Perns having divided fronds, is called the rachis. 
The fronds — in the leafy part — are either simple or more or less divided, and have different 
terms applied to them, according to the nature of the division. If a frond is separated into 
distinct leaflets, and these are simple, it is said to be pinnate (Pig. 5, 36, &c.) ; if the leaflets, 
called also pinnae, are again divided into distinct leaflets, they are said to be pinnate, and the 
frond is bipinnate ; when they are again divided the frond becomes tripinnate, and so on. If 
the divisions are not distinct, but are united at the base, and are not otherwise divided, they 
are then pinnatifid (Pig. 2, 14, &c.) ; and so, when twice or thrice divided on the same plan, 
they become hipinnatifid, tripinnatifid, and so on. Pronds very much divided, that is, more 
divided than tripinnate, are in general terms called decompound. These and similar terms, 
descriptive of form, are applied in the same sense as in other departments of botany : such are 
flahellate, palmate, pedate, sagittate, &c. 
The fronds are traversed by a series of veins, which are, in fact, the ramifications of the 
system of vascular structure, which forms the main hidk of the stipes and rachis. The midi'ib 
of a fi-oud or pinna is sometimes called the costa : the first series of branches fii’om this are the 
veins, the secondary series the venules, and the tertiary series the veinlets (Pig. 13, 59, &c.). 
The arrangement of these different series of veins in the substance of the frond is called the 
venation. 
Great variety of venation is exliibitcd among the Perns, the voi’ious modes in which it 
