rock, ill wliich its roots had no kind of hold ; tliis was the character
of tlie plant when most luxuriant, but I found other and
mucli smaller plants which possessed more root and less rhizoma,
and the roots were fixed in a thin layer of moist earth, among a
profusion of moss and Hymenophyllum.
The fronds make their appearance in summer ; as late as the
beginning of August I found many fronds in the young state,
shewn to the left of the illustration, hy which it will he seen
that the pinnæ are individually circinate, as well as the entire
frond. I t must be at least as late as October before the fronds
arrive at maturity; and I found those of the previous year,
very dark coloured indeed, hut quite unfaded at the time of
my visit.
The form of the frond is triangular, the apex being elongated
and pointed ; it is pinnate, the pinnæ being also pinnate, and
tlie pinnulæ pinnate : perhaps it would be more correct to
describe the hard wiry stem-hke veins as thus divided, and to
say that each of these veins is furnished on each side with a
semimembranous wing, extending throughout its length, for
this is the case. The entire frond is composed of these wings,
and all its divisions ai-e consequently narrow and linear ; the
wing is without visible veins of any kind. The figure represents
the plant of less than the natural size.
This genus comprises many very beautiful exotic species,
principally iiiliahitants of tropical climates; in some of the West
India Islands they clothe the trunks of trees with a most graceful
and elegant drapery. The mode of fructification in T. speciosum
is very singular. The mass of thecæ is attached to the
centre of a vein, after its ultimate division, and invariably to
that one which is situated nearest the midvein of the frond, pinna
or pinnula, as the case may he. At the attachment of this mass
of thecæ the wing loses its green and semimembranous appearance
; its cuticles separate, and form an elongate cup-shaped
receptacle, which includes the mass of thecæ. The vein itself,
after bearing the thecæ, runs through the receptacle, and
projects considerably beyond its extremity, in the similitude of
a bristle.
This definition of the generic characters appears to me the
correct one, but I subjoin that given by Sir J. E. Smith, not
simply on account of its remarkable discrepancy with my own
riew of the structure, hut because it is the one usually received.
“ Masses of tliecæ, roundish, terminal, imbedded in the margin
or segments of the frond. Indusium urn-shaped, of the texture
of the frond, and continuous with it, of one leaf, dilated upwards,
and opening outwards, permanent. Thecæ several, sessile,
crowded at the base of a permanent, cylindrical, common receptacle,
whose capillary naked point projects beyond the cover,
each roundish, of two valves, bound hy a vertical jointed ring.”-—•
Eng. Flora, Vol. iv. p. 324>.
Speaking of our British species. Smith describes the fructification
thus “ A few of the uppermost segments, terminating
each in a solitary, imbedded, oblong, or cylindrical, somewhat
urn-shaped cover, continued from the leaf, slightly winged at the
sides, a little dilated, not lohed at the orifice. Thecæ, in around
mass, attached to the base of a cylindrical slender receptacle or
column, which, in an early state does not project beyond the
cover, hut afterwards acquires three or four times the length of
that part.”—Id. I. c.
This fern being, as regards Great Britain, so peculiarly Irish,
I have ventured to introduce the sketch of a building equally
characteristic of that country.