f
n , ,
♦ r
C I i
I I I
i '
E »
| t > '
h *
p
r * Il
1 ^ ,
■IVS
I » ' •
«II.
♦ I
i r I
S v i
li : '
i; • '.
66 FERNS OF NORTH AMERICA.
D e s c r i p t io n . — The root-stock is rather stout, not more than
one or two inches long, and is heavily clothed with narrow bright-
brown scales. The remains of old stalks still adhering to it considerably
increase its apparent size. The stalks are commonly
about four inches long, straight or slightly curved, wiry, dark-
brown or almost black, and polished, though not so shining as the
stalks of most species of Adiantum. The fronds are about as
long as the stalk, and nearly as broad as they are long ; so that the
general outline is broadly triangular. They are pinnately decompound
to the fourth and even to the fifth degree of sub-division,
and bear at the ends of the ultimate branchlets very minute
obovate or often two- or three- lobed pinnules, having the upper
surface of a pale bluish-green, and the under surface covered with
a dense white powder. The main rachis and its primary and
secondary branches are singularly flexuous, being bent at an
obtuse angle alternately to right and left, and bearing a branch or
branchlet on the outer or convex side of each angle. From this
habit it results that the branches are never opposite or in pairs,
but almost uniformly alternate. It sometimes happens that the
branchlet is nearly as large as the branch from which it springs ;
and then the method of division is dichotomous, or forking, rather
than pinnate. The lowest pinna (for there is but one lowest, not
a pair) and the next to the lowest have not infrequently two, three,
or even four branchlets arising from the upper side before any are
developed from the lower. This may perhaps arise from suppression
of the branchlets of the inferior side, or from a twisting of
the secondary midrib. It is most noticeable in the figures given
FERNS OF NORTH AMERICA. 67
by Kunze, and in specimens collected in Arizona by Dr. Edward
Palmer. These specimens are exaggerated examples of what Dr.
Milde has called anadromy f while the plant from which Mr.
Emerton has taken his drawing has the first branch of the lowest
pinna placed on the inferior side, and is therefore catadronious.
All the branches and branchlets are dark brown and smooth, like
the stalk ; and they are so much refracted and divaricating, that
the several fronds of one plant are almost always much entangled,
so that they are difficult to separate without injury.
The sporangia are comparatively few : they are placed on the
upper part of the free veinlets, and appear as a row or narrow
band of dark-brown particles breaking through the white powdery
mass. This powdery mass is found in ferns of several different
genera, — Notholæna, Cheilanthes, and Gymnogramme. It is
either white, creamy, pale yellow or deep yellow, the color varying
even in fronds of the same species. In one Notholæna from
Natal the powder is even pinkish in color. The powdery species
of each of these genera have been separated by various authors
into special genera, named respectively Cincinalis, Alettrilopleris,
and Ceropteris. But these genera have been rejected by the more
‘ Milde, F il. Europæ et Atlantidis, p. 8 : “ Segments of the second degree,
especially at the base of the lamina, are commonly arranged according to a most
distinct order, which arrangement is not rarely most useful in sa fe ly distinguishing
related species. T h is arrangement is either anadromoiis or caiadromoiis. Tho se
segments o f the second degree arc called anadromous of which the first one is
placed on the superior side of the segment of the first degree [primary pinna] : therefore
those are catadromous o f which the first one is observed on the lower side.”
iin
i i f
; (•
i 'i I I
ii ■ ' - . 'N
' w _ J
»
I
• a l - - :
1 ;
. 1 . . ..
1
,1
. » ■
] i n ri
( rj y.1
___