Kl . ■ T I ”
; ji
I ,
iif,
’r l
'« * ; i'
I
• i l I •
i é»
! | i i
i; I
I f i l
' C i
* V f î
Çli' i
M
h : l i "
l i ' i
1 ’ >1
i
'
The root-stock, though seldom over a few inches long,
is erect and very woody. It produces a crown of many
fronds, and emits from just below the insertion of nearly
every stalk, as Mettenius has indicated, a long and slender
runner. These runners are rather rigid, less than a line in
thickness, but often over two feet long. They root freely,
and produce many lateral buds, from which new plants
arise, very much as new strawberry-plants are produced from
the lateral buds of runners. In this way there is often
formed a large mass of the plant, as was found by Dr.
Garber in the low hummocks of Southwestern Florida.
The stalk is rigid, terete, dark-brown, shining, but more
or less chaffy, and the section discloses a very strong exterior
sheath of scierenchyma, and three rather slender fibro-vascular
threads buried in the internal mass of brown parenchyma.
The runners have but one fibro-vascular thread.
The chaff of the root-stock, like that found on the runners
and on the stalks when young, consists of very slender
ferruginous scales, nearly entire in the Florida specimens, but
in exotic plants sometimes conspicuously ciliate. The rachis is
more or less chaffy-fibrillose, especially along the upper side.
The fronds have no definite length, as they continue to
grow indefinitely from the apex, and may sometimes reach a
length of six or eight feet before the growth is arrested by
some accidental injury. Among many specimens in my collection,
I find only one (from Venezuela, collected by Fendler)
in which the frond has a proper pinnatifid apex. This frond
is about three feet long and three inches wide, and is in full
fruit.
The pinnæ are lanceolate or oblong-linear, sessile and articulated
to the rachis, leaving a minute elliptical scar when
they finally drop off. The base is usually cordate and auricled,
especially on the upper side, the auricles obtuse and
covering the lower surface of the rachis. The apex of the
pinnæ is either acute or obtuse, and the margin is crenulate-
serrate. The veins are mostly once forked near the midrib,
the branches running obliquely almost to the margin, and
their apices enlarged and thickened. The position of these
thickened apices is commonly marked on the upper surface
of the frond by the presence of a minute round white scale.
By the use of dilute hydrochloric acid the white calcareous
matter may be dissolved out, and only a delicate cellular film
remains. Similar calcareous dots have been observed on the
fronds of Polypodiuni Phyllitidis and many other ferns. Many
of the pinnæ are fertile, the sori being produced on the thickened
apices of the upper veinlet of each pair. The indusia vary
much in shape, being now round-reniform, and attached near
the centre, much as in section Nephrodium of Aspidium,
and now merely arched, and attached by a broad hollow base
to the superior side of the incrassated apex of the fertile
veinlet. Both forms may often be seen on the same pinna.
The sporangia have a ring of about fourteen or fifteen
joints, and the spores are ovoid.
Hooker and Baker reduce the species of Nephrolepis to
/ ' I T
:!i *
.I)"
c ’
i ii
II'. J