The Fern Lover\'s Companion by George Henry Tilton
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7 [Illustration: A Fern Lover]
The Fern Lover's Companion
A Guide for the Northeastern States
and Canada
BY
GEORGE HENRY TILTON, A.M.
"This world's no blot for us
Nor blank; it means intensely and it means good
To find its meaning is my meat and drink."
[Illustration]
DEDICATION
To Alice D. Clark, engraver of these illustrations, who has spared no pains
to promote the artistic excellence of this work, and to encourage its
progress, these pages are dedicated with the high regards of THE AUTHOR.
CONTENTS
List of Illustrations
Preface
Introduction
Key to Genera
Classification of Ferns
The Polypodies
The Bracken Group:
Bracken
Cliff Brakes
Rock Brake
The Lip Ferns (_Cheilanthes_)
The Cloak Fern (_Notholaena_)
The Chain Ferns
The Spleenworts:
The Rock Spleenworts. _Asplenium_
The Large Spleenworts. _Athyrium_
Hart's Tongue and Walking Leaf
The Shield Ferns:
Christmas and Holly Fern
Marsh Fern Tribe
The Beech Ferns
The Fragrant Fern
The Wood Ferns
The Bladder Ferns
The Woodsias
The Boulder Fern (_Dennstaedtia_)
Sensitive and Ostrich Ferns
The Flowering Ferns (_Osmunda_)
Curly Grass and Climbing Fern
Adder's Tongue
The Grape Ferns:
Key to the Grape Fern
Moonwort
Little Grape Fern
Lance-leaved Grape Fern
Matricary Fern
Common Grape Fern
Rattlesnake Fern
Filmy Fern
Noted Fern Authors
Fern Literature
Time List for Fruiting of Ferns
Glossary
Note: Meaning of Genus and Species
Checklist
LIST OF ILLUSTRATIONS
A Fern Lover
Prothallium Diagram
Pinnate Frond
Bipinnate Frond
Pinnatifid Frond
Spore Cases
Linen Tester
Curly Grass. _Schizaea_
Cinnamon Fern. _Osmunda cinnamomea_
Sensitive Fern. _Onoclea sensibilis_
Ostrich Fern. _Onoclea Struthiopteris_
Interrupted Fern. _Osmunda Claytoniana_
Climbing Fern. _Lygodium_
Flowering Fern. _Osmunda regalis spectabilis_
Adder's Tongue. _Ophioglossum_
Grape Fern. _Botrychium_
Polypody. _Polypodium_
Beech Fern. _Phegopteris_
Cloak Fern. _Notholaena_
Filmy Fern. _Trichomanes_
Bracken. _Pteris_
Maidenhair. _Adiantum_
Cliff Brake. _Pellaea_
Lip Fern. _Cheilanthes_
Rock Brake. _Cryptogramma_
Chain Fern. _Woodwardia_
Shield Fern. _Polystichum_
Wood Fern. _Aspidium_
Bladder Fern. _Cystopteris_
Woodsia
Hayscented Fern. _Dennstaedtia_
Hart's Tongue. _Scolopendrium_
Walking Fern. _Camptosorus_
Asplenium Type
Athyrium Type
Sporangia of the Five Families
Indusium
Common Polypody. _Polypodium vulgare_
Sori of Polypody
Polypody in mass (Greenwood)
Gray Polypody. _Polypodium incanum_
Brake. Bracken. Sterile Frond
Bracken. Fertile Frond
Bracken, var. _pseudocaudata_
Spray of Maidenhair
Sori of Maidenhair
Maidenhair. _Adiantum pedatum_
Alpine Maidenhair
Venus-Hair Fern. _Adiantum capillus-veneris_
Purple Cliff Brake. _Pellaea atropurpurea_
Dense Cliff Brake. _Cryptogramma densa_
Slender Cliff Brake. _Cryptogramma Stelleri_
Parsley Fern. _Cryptogramma acrostichoides_
Alabama Lip Fern. _Cheilanthes alabamensis_
Hairy Lip Fern. _Cheilanthes lanosa_
Slender Lip Fern. _Cheilanthes Feei_
Pinnae of Slender Lip Fern
Powdery Cloak Fern. _Notholaena dealbata_
Common Chain Fern. _Woodwardia virginica_
Net-veined Chain Fern. _Woodwardia areolata_
The Spleenworts
Pinnatifid Spleenwort. _Asplenium pinnatifidum_
Scott's Spleenwort. _Asplenium ebenoides_
Green Spleenwort. _Asplenium viride_
Maidenhair Spleenwort. _Asplenium Trichomanes_
Maidenhair Spleenwort. _Asplenium Trichomanes_ (Fernery)
Ebony Spleenwort. _Asplenium platyneuron_
Bradley's Spleenwort. _Asplenium Bradleyi_
Mountain Spleenwort. _Asplenium montanum_
Rue Spleenwort. _Asplenium Ruta-muraria_
Rootstock of Lady Fern (Two parts)
Sori of Lady Fern. _Athyrium angustum_
Varieties of Lady Fern
Lowland Lady Fern. _Athyrium asplenioides_
Silvery Spleenwort. _Athyrium acrostichoides_
Narrow-leaved Spleenwort. _Athyrium angustifolium_
Pinnae and Sori of _Athyrium angustifolium_
Sori of _Scolopendrium vulgare_
Hart's Tongue. _Scolopendrium vulgare_
Walking Fern. _Camptosorus rhizophyllus_
Christmas Fern. _Polystichum acrostichoides_
Varieties of Christmas Fern
Braun's Holly Fern. _Polystichum Braunii_
Holly Fern. _Polystichum Lonchitis_
Marsh Fern. _Aspidium Thelypteris_
Marsh Fern, in the mass
Massachusetts Fern. _Aspidium simulatum_
New York Fern. _Aspidium noveboracense_
Sori of _Aspidium noveboracense_
Pinnae and Sori of _Aspidium noveboracense_
Oak Fern. _Phegopteris Dryopteris_
Northern Oak Fern. _Phegopteris Robertiana_
Broad Beech Fern. _Aspidium hexagonoptera_
Long Beech Fern. _Aspidium polypedioides_
Fragrant Fern. _Aspidium fragrans_
Marginal Shield Fern. _Aspidium marginale_
Crown of Fronds of _Aspidium marginale_
Sori of _Aspidium marginale_
Male Fern. _Aspidium Filix-mas_
_Aspidium Filix-mas_ and details
Goldie's Shield Fern. _Aspidium Goldianum_
_Aspidium Goldianum_, in the mass
Crested Shield Fern. _Aspidium cristatum_
Crested Shield Fern. _Aspidium cristatum_ (No. 2)
Clinton's Shield Fern. _Aspidium cristatum_ var. _Clintonianum_
Crested Marginal Fern. _Aspidium cristatum x marginale_
_Aspidium cristatum x marginale_, in the mass
Boott's Shield Fern. _Aspidium Boottii_
Spinulose Shield Fern. _Aspidium spinulosum_
_Aspidium spinulosum_ var. _intermedium_
_Aspidium spinulosum_ var. _americanum_
Bulblet Bladder Fern. _Cystopteris bulbifera_
_Cystopteris bulbifera_ with sprouting bulb
Fragile Bladder Fern. _Cystopteris fragilis_
Rusty Woodsia. _Woodsia ilvensis_
Northern Woodsia. _Woodsia alpina_
Details of Alpine Woodsia
Blunt-lobed Woodsia. _Woodsia obtusa_
Smooth Woodsia. _Woodsia glabella_
Hayscented Fern. _Dennstaedtia punctilobula_
Forked variety of _Dennstaedtia punctilobula_
Field View of _Dennstaedtia punctilobula_
Pinnae and Sori of _Dennstaedtia punctilobula_
Meadow View of Sensitive Fern
Obtusilobata Forms of Sensitive Fern, Leaf to Fruit
Sori of Sensitive Fern
Sensitive Fern. _Onoclea sensibilis_
Sensitive Fern, Fertile and Sterile Fronds on Same Plant
Ostrich Fern. _Onoclea Struthiopteris_. Fertile Fronds
Ostrich Fern. Sterile Fronds
Sori and Sporangia of Ostrich Fern
Royal Fern. _Osmunda regalis spectabilis_
Sori of Royal Fern
Interrupted Fern. _Osmunda Claytoniana_
Interrupted Fern. Fertile Pinnules Spread Open
Cinnamon Fern. _Osmunda cinnamomea_
Cinnamon Fern. Leaf Gradations
Two Varieties of Cinnamon Fern
_Osmunda cinnamomea glandulosa_
Curly Grass. _Schizaea pusilla_
Sporangia of Curly Grass
Climbing Fern. _Lygodium palmatum_
Adder's Tongue. _Ophioglossum vulgatum_
Moonwort. _Botrychium Lunaria_
Moonwort, Details
Little Grape Fern. _Botrychium simplex_
Lance-leaved Grape Fern. _Botrychium lanceolatum_
Matricary Grape Fern. _Botrychium ramosum_
Common Grape Fern. _Botrychium obliquum_
_Botrychium obliquum_ var. _dissectum_
_Botrychium obliquum_ var. _oneidense_
Ternate Grape Fern. _Botrychium ternatum_ var. _intermedium_
Ternate Grape Fern. _B. ternatum_ var. _intermedium_
Rattlesnake Fern. _Botrychium virginianum_
Filmy Fern. _Trichomanes Boschianum_
Fruiting Pinnules of Filmy Fern
Crosiers
Noted Fern Authors
Spray of the Bulblet Bladder Fern
PREFACE
A lover of nature feels the fascination of the ferns though he may know
little of their names and habits. Beholding them in their native haunts,
adorning the rugged cliffs, gracefully fringing the water-courses, or
waving their stately fronds on the borders of woodlands, he feels their
call to a closer acquaintance. Happy would he be to receive instruction
from a living teacher: His next preference would be the companionship of a
good fern book. Such a help we aim to give him in this manual. If he will
con it diligently, consulting its glossary for the meaning of terms while
he quickens his powers of observation by studying real specimens, he may
hope to learn the names and chief qualities of our most common ferns in a
single season.
Our most productive period in fern literature was between 1878, when
Williamson published his "Ferns of Kentucky," and 1905, when Clute
issued, "Our Ferns in Their Haunts." Between these flourished D.C. Eaton,
Davenport, Waters, Dodge, Parsons, Eastman, Underwood, A.A. Eaton, Slosson,
and others. All their works are now out of print except Clute's just
mentioned and Mrs. Parsons' "How to Know the Ferns." Both of these
are valuable handbooks and amply illustrated. Clute's is larger, more
scholarly, and more inclusive of rare species, with an illustrated key to
the genera; while Mrs. Parsons' is more simple and popular, with a naive
charm that creates for it a constant demand.
We trust there is room also for this unpretentious, but progressive,
handbook, designed to stimulate interest in the ferns and to aid the
average student in learning their names and meaning. Its geographical
limits include the northeastern states and Canada. Its nomenclature follows
in the main the seventh edition of Gray's Manual, while the emendations
set forth in _Rhodora_, of October, 1919, and also a few terms of later
adoption are embodied, either as synonyms or substitutes for the more
familiar Latin names of the Manual, and are indicated by a different type.
In every case the student has before him both the older and the more recent
terms from which to choose. However, since the book is written primarily
for lovers of Nature, many of whom are unfamiliar with scientific terms,
the common English names are everywhere given prominence, and strange to
say are less subject to change and controversy than the Latin. There is
no doubt what species is meant when one speaks of the Christmas fern, the
ostrich fern, the long beech fern, the interrupted fern, etc. The use of
the common names will lead to the knowledge and enjoyment of the scientific
terms.
A friend unfamiliar with Latin has asked for pointers to aid in pronouncing
the scientific names of ferns. Following Gray, Wood, and others we have
marked each accented syllable with either the grave (`) or acute ()
accent, the former showing that the vowel over which it stands has its long
sound, while the latter indicates the short or modified sound. Let it be
remembered that any syllable with either of these marks over it is the
accented syllable, whose sound will be long or short according to the slant
of the mark.
We have appropriated from many sources such material as suited our purpose.
Our interest in ferns dates back to our college days at Amherst, when we
collected our first specimens in a rough, bushy swamp in Hadley. We found
here a fine colony of the climbing fern (_Lygodium_). We recall the slender
fronds climbing over the low bushes, unique twiners, charming, indeed, in
their native habitat. We have since collected and studied specimens of
nearly every New England fern, and have carefully examined most of the
other species mentioned in this book. By courtesy of the librarian, Mr.
William P. Rich, we have made large use of the famous Davenport herbarium
in the Massachusetts Horticultural library, and through the kindness of
the daughter, Miss Mary E. Davenport, we have freely consulted the larger
unmounted collection of ferns at the Davenport homestead, at Medford,[1]
finding here a very large and fine assortment of _Botrychiums_, including a
real _B. ternatum_ from Japan.
[Footnote 1: Recently donated to the Gray Herbarium.]
For numerous facts and suggestions we are indebted to the twenty volumes of
the _Fern Bulletin_, and also to its able editor, Mr. Willard N. Clute. To
him we are greatly obligated for the use of photographs and plates, and
especially for helpful counsel on many items. We appreciate the helpfulness
of the _American Fern Journal_ and its obliging editor, Mr. E.J. Winslow.
To our friend, Mr. C.H. Knowlton, our thanks are due for the revision of
the checklist and for much helpful advice, and we are grateful to Mr.
S.N.F. Sanford, of the Boston Society of Natural History, for numerous
courtesies; but more especially to Mr. C.A. Weatherby for his expert and
helpful inspection of the entire manuscript.
The illustrations have been carefully selected; many of them from original
negatives bequeathed to the author by his friend, Henry Lincoln Clapp,
pioneer and chief promoter of school gardens in America. Some have been
photographed from the author's herbarium, and from living ferns. A few
are from the choice herbarium of Mr. George E. Davenport, and also a few
reprints have been made from fern books, for which due credit is given. The
Scott's spleenwort, on the dedication page, is reprinted from Clute's "Our
Ferns in Their Haunts."
INTRODUCTION
Thoreau tells us, "Nature made a fern for pure leaves." Fern leaves are in
the highest order of cryptogams. Like those of flowering plants they are
reinforced by woody fibres running through their stems, keeping them erect
while permitting graceful curves. Their exquisite symmetry of form, their
frequent finely cut borders, and their rich shades of green combine to make
them objects of rare beauty; while their unique vernation and method of
fruiting along with their wonderful mystery of reproduction invest them
with marked scientific interest affording stimulus and culture to the
thoughtful mind. By peculiar enchantments these charming plants allure the
ardent Nature-lover to observe their haunts and habits.
"Oh, then most gracefully they wave
In the forest, like a sea,
And dear as they are beautiful
Are these fern leaves to me."
As a rule the larger and coarser ferns grow in moist, shady situations, as
swamps, ravines, and damp woods; while the smaller ones are more apt to be
found along mountain ranges in some dry and even exposed locality. A tiny
crevice in some high cliff is not infrequently chosen by these fascinating
little plants, which protect themselves from drought by assuming a mantle
of light wool, or of hair and chaff, with, perhaps, a covering of white
powder as in some cloak ferns--thus keeping a layer of moist air next to
the surface of the leaf, and checking transpiration.
Some of the rock-loving ferns in dry places are known as "resurrection"
ferns, reviving after their leaves have turned sere and brown. A touch of
rain, and lo! they are green and flourishing.
Ferns vary in height from the diminutive filmy fern of less than an inch
to the vast tree ferns of the tropics, reaching a height of sixty feet or
more.
REPRODUCTION
Ferns are propagated in various ways. A frequent method is by perennial
rootstocks, which often creep beneath the surface, sending up, it may be,
single fronds, as in the common bracken, or graceful leaf-crowns, as in the
cinnamon fern. The bladder fern is propagated in part from its bulblets,
while the walking leaf bends over to the earth and roots at the tip.
[Illustration: MALE SHIELD FERN. Fern Reproduction by the Prothallium]
Ferns are also reproduced by spores, a process mysterious and marvellous as
a fairy tale. Instead of seeds the fern produces spores, which are little
one-celled bodies without an embryo and may be likened to buds. A
spore falls upon damp soil and germinates, producing a small, green,
shield-shaped patch much smaller than a dime, which is called a prothallium
(or prothallus). On its under surface delicate root hairs grow to give it
stability and nutriment; also two sorts of reproductive organs known as
antheridia and archegonia, the male and female growths analogous to the
stamens and pistils in flowers. From the former spring small, active,
spiral bodies called antherozoids, which lash about in the moisture of
the prothallium until they find the archegonia, the cells of which are so
arranged in each case as to form a tube around the central cell, which is
called the ooesphere, or egg-cell, the point to be fertilized. When one
of the entering antherozoids reaches this point the desired change is
effected, and the canal of the archegonium closes. The empty ooesphere
becomes the quickened ooesphore whose newly begotten plant germ unfolds
normally by the multiplication of cells that become, in turn, root, stem,
first leaf, etc., while the prothallium no longer needed to sustain its
offspring withers away.[1]
[Footnote 1: In the accompanying illustration, it should be remembered that
the reproductive parts of a fern are microscopic and cannot be seen by the
naked eye.]
Fern plants have been known to spring directly from the prothallus by a
budding process apart from the organs of fertilization, showing that Nature
"fulfills herself in many ways."[2]
[Footnote 2: The scientific term for this method of reproduction is apogamy
(apart from marriage). Sometimes the prothallus itself buds directly from
the frond without spores, for which process the term apospory is used.
(Meaning, literally, without spores.)]
VERNATION
All true ferns come out of the ground head foremost, coiled up like a
watch-spring, and are designated as "fiddle-heads," or crosiers. (A real
crosier is a bishop's staff.) Some of these odd young growths are covered
with "fern wool," which birds often use in lining their nests. This wool
usually disappears later as the crosier unfolds into the broad green blade.
The development of plant shoots from the bud is called vernation (Latin,
_ver_ meaning spring), and this unique uncoiling of ferns, "circinnate
vernation."
VEINS
The veins of a fern are free, when, branching from the mid-vein, they do
not connect with each other, and simple when they do not fork. When
the veins intersect they are said to anastomose (Greek, an opening, or
network), and their meshes are called areolae or areoles (Latin, _areola_, a
little open space).
EXPLANATION OF TERMS
A frond is said to be pinnate (Latin, _pinna_, a feather), when its primary
divisions extend to the rachis, as in the Christmas fern (Fig. 1). A frond
is bipinnate (Latin, _bis_, twice) when the lobes of the pinnae extend to
the midvein as in the royal fern (Fig. 2). These divisions of the pinnae are
called pinnules. When a frond is tripinnate the last complete divisions are
called ultimate pinnules or segments. A frond is pinnatifid when its lobes
extend halfway or more to the rachis or midvein as in the middle lobes
of the pinnatifid spleenwort (Fig. 3). The pinnae of a frond are often
pinnatifid when the frond itself is pinnate; and a frond may be pinnate
in its lower part and become pinnatifid higher up as in the pinnatifid
spleenwort just mentioned (Fig. 3).
[Illustration: Fig. 1]
[Illustration: Fig. 2]
[Illustration: Fig. 3]
The divisions of a pinnatifid leaf are called segments; of a bipinnatifid
or tripinnatifid leaf, ultimate segments.
SPORANGIA AND FRUIT DOTS
Fern spores are formed in little sacs known as spore-cases or sporangia
(Fig. 4). They are usually clustered in dots or lines on the back or margin
of a frond, either on or at the end of a small vein, or in spike-like
racemes on separate stalks. Sori (singular _sorus_, a heap), or fruit dots
may be naked as in the polypody, but are usually covered with a thin,
delicate membrane, known as the indusium (Greek, a dress, or mantle). The
family or genus of a fern is often determined by the shape of its indusium;
e.g., the indusium of the woodsias is star-shaped; of the Dicksonias,
cup-shaped; of the aspleniums, linear; of the wood ferns, kidney-shaped,
etc.
[Illustration: Fig. 4]
In many ferns the sporangia are surrounded in whole or in part by a
vertical, elastic ring (annulus) reminding one of a small, brown worm
closely coiled (Fig. 4). As the spores mature, the ring contracts and
bursts with considerable force, scattering the spores. The spores of the
different genera mature at different times from May to September. A good
time to collect ferns is just before the fruiting season. (For times of
fruiting see individual descriptions or chronological chart on page 220.)
HELPFUL HINTS
The following hints may be helpful to the young collector:
1. A good lens with needles for dissecting is very helpful in examining the
sori, veins, glands, etc., as an accurate knowledge of any one of these
items may aid in identifying a given specimen. Bausch and Lomb make a
convenient two-bladed pocket glass for about two dollars.[1]
[Footnote 1: In the linen tester here figured (cost $1.50) the lens is
mounted in a brass frame which holds it in position, enabling the dissector
to use both hands. A tripod lens will also be found cheap and serviceable.]
[Illustration]
2. Do not exterminate or weaken a fern colony by taking more plants than it
can spare. In small colonies of rare ferns take a few and leave the rest to
grow. It is decidedly ill-bred to rob a locality of its precious plants.
Pick your fern leaf down close to the root-stock, including a portion of
that also, if it can be spared. Place your fronds between newspaper sheets
and lay "dryers" over them (blotting paper or other absorbent paper). Cover
with a board or slat frame, and lay on this a weight of several pounds,
leaving it for twenty-four hours; if the specimens are not then cured,
change the dryers. Mount the prepared specimens on white mounting sheets.
The regulation size is 16-1/2 by 11-1/2 inches. The labels are usually
3-3/4 by 1-3/4 inches. A sample will suggest the proper inscription.
HERBARIUM OF JOHN DOE
_Ophioglossum vulgatum_, L.
(Adder's Tongue)
Willoughby Lake, Vt.
August 19, 1911. Wet meadow.
Coll. X.Y.Z. Rather common
but often overlooked
Place the label at the lower right-hand corner of the sheet, which is now
ready to be laid in the genus cover, usually of manila paper 16-1/2 by 12
inches.
It is well to jot down important memoranda at the time of collecting. This
is the method in use at the Gray Herbarium in Cambridge. It can, of course,
be modified to suit one's own taste or convenience. The young collector can
begin by simply pressing his specimens between the leaves of a book,
the older and coarser the better; and he can mount them in a blank book
designed for the purpose, or if he has only a common blank book, he can cut
out some of the leaves, alternately with others left in place, as is often
done with a scrap book, that when the book is full it may not be crowded at
the back. Or he can use sheets of blank paper of any uniform size and mount
the specimens on these with gummed strips, and then group them, placing
those of the same genus together. Such an extemporized herbarium, though
crude, will serve for a beginning, while stimulating his interest, and
advancing his knowledge of the ferns. Let him collect, press, and mount
as many varieties as possible, giving the name with date and place of
collecting, etc. Such a first attempt may be kept as a reminder of pleasant
hours spent in learning the rudiments of a delightful study.
We cannot insist too strongly upon the necessity of handling and studying
the living plant. Every student needs to observe for himself the haunts,
habits, and structure of real ferns. We would say to the young student,
while familiarizing yourself with the English names of the ferns, do not
neglect the scientific names, which often hold the key to their meaning.
Repeat over and over the name of each genus in soliloquy and in
conversation until your mind instantly associates each fern with its family
name--"_Adiantum_," "_Polystichum_," "_Asplenium_," and all the rest. Fix
them in the memory for a permanent asset. With hard study and growing
knowledge will come growing attachment. How our great expert, Mr.
Davenport, loved the ferns! He would handle them with gentle touch, fondly
stroke their leaves, and devoutly study their structure, as if inspired by
the All-wise Interpreter.
"Move along these shades
In gentleness of heart: with gentle hand
Touch--for there is a spirit in the woods."
KEY TO THE GENERA
This key, in illustrating each genus, follows the method of Clute in "Our
Ferns in Their Haunts," but substitutes other and larger specimens. Five of
these are from Waters' "Ferns" by permission of Henry Holt & Co.
As the indusium, which often determines the name of a fern, is apt in some
species to wither early, it is important to secure for study not only a
fertile frond, but one in as good condition as possible. For convenience
the ferns may be considered in two classes.
I
THOSE WHICH HAVE THE FRUITING PORTION IN GREENISH, BERRY-LIKE STRUCTURES
AND NOT ON THE BACK OF FRONDS
A. FRUITING FRONDS WHOLLY FERTILE
(Fertile and sterile fronds entirely unlike)
[Illustration]
1. Fruit in a one-sided spike in two ranks; plants very small; sterile
fronds thread-like and tortuous.
Curly Grass. _Schizaea_.
[Illustration]
2. Fruit in a club-shaped, brown or cinnamon-colored spike loaded with
sporangia; fruit in early spring.
Cinnamon Fern. _Osmunda cinnamomea_.
[Illustration]
3. Fruit in berry-like, greenish structures in a twice pinnate spike, which
comes up much later than the broad and coarse pinnatifid sterile fronds.
Wet ground. Sensitive Fern. _Onoclea_.
[Illustration]
4. Fruit in pod-like or necklace-like pinnae; fertile frond pinnate; sterile
frond tall, pinnatifid; fruit late.
Ostrich Fern. _Onoclea struthiopteris_.
B. FRUITING FRONDS PARTLY STERILE
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