1897.
L. M. Underwood, Molds, Mildews and Mushrooms, Xew
York, 1899.
C. B. Plowrioiit, .1 Monograph of the British Uredineae and
Ustilagincaea, London, 1889.
16
CHAPTER XIV
PHYLUM VIII. BRYOPHYTA
THE MOSSWORTS
418. This phylum includes plants of much greater
complexity than any of the preceding. In very many
cases they have distinct stems and leaves, whose tissues
often show a differentiation into several varieties. In
the sexual organs the cell to be fertilized (the egg) is from
the first enclosed in a protective layer of cells, and after
fertilization it develops into a complex spore-bearing
body.
419. The life-cycle of the Mossworts includes a dis-
tinct alternation of generations. The immediate prod-
uct of the fertilization of an egg is not a thalloid or leafy
plant Uke that which bears the sexual organs, but, on the
contrary, it is a many-celled leafless structure, spherical
or approximately cylindrical, which eventually produces
spores internally. The plant which produces the sexual
organs is the gametophyte, while that which produces the
spores is the sporophyte.
420. So the Mossworts have a marked duality, and we
must consider both phases when we wish to get a complete
idea of any particular plant. This duality has permitted
the acquisition of the land habit, since the gametophytes
have retained some of their aquatic characteristics, while
the sporophytes have become modified for a terrestrial
life. Accordingly in Bryophytes we find the beginning of
the terrestrial habit in green plants.
242
ALTERNATION OF GENERATIONS 243
421. Mossworts may then be described as green plants
in which the gametophyte is a prostrate or erect some-
what long-Hvcd phint, producing antherids, and oogones
(the latter enclosed in archegones). After fertilization a
distinct structure, the sporophyte, is produced, but al-
though it rests on and in the gametophyte and obtains its
supply of water and much of its food from it there is
no organic connection between them. In this sporo-
phyte certain internal cells (the ''spore mother-cells")
divide twice and thus produce internally four spores
each. These eventually germinate and produce other
gametophytes.
422. Here it should be noted that the nuclei of the
gametophyte cells contain a definite number of chromo-
somes, and that on the fertilization of the egg this number
is doubled. This double number is maintained in the
sporophyte until spores are formed by division into fours,
at which time a reduction takes place to the original num-
ber. So in this phylum the two generations are separable
also by their chromosome numbers in addition to the
other more obvious differences.
423. The antherids are complex structures. They are
usually short-stalked, and consist of a layer of large
])Oundary cells within which are very numerous, small,
more or less cu])ical cells, each of which produces in-
ternally an elongated, more or less spiral, biciliate sperm.
The walls of these spermatogenous cells dissolve, leaving
the sperms free within the cavity of the antherid. By the
rupture of the apical cells the sperms escape. This
occurs only when the antherid is covered with water (rain,
dew, etc.).
424. The archegone is a flask-shaped, elongated organ,
consisting of an enlarged lower part (venter) containing
the egg, aljove which is the slender neck, at first closed at
244 PHYLUM VIII. BRYOPHYTA
the top and surrounding the row of canal cells, but later
open with a continuous passage to the egg (owing to the
dissolution of the canal cells). In fertilization which
takes place in water, the sperms pass down the tubular
neck to the egg below.
425. Mossworts are of small size,- rarely exceeding 10 or
15 centimeters in height. They generally prefer moist
situations upon the ground, or on the sides of trees or
rocks. All told there are somewhat more than 16,000
species. Two classes may be distinguished, as follows:
Mostly bilateral, often thalloid, creeping gametophytes,
usually with splitting sporophytes, and mostly having
elaters Class Hepaticae.
Multilateral, leafy -stemmed, mostly erect gametophytes, usu-
ally with circularly dehiscing sporophytes, and without
elaters Class IMusci.
Class HEPATICAE. Liverworts
426. In the lower Liverworts the gametophy te is a flat,
expanded thallus of parenchymatous tissue, and this
gradually differentiates into a leafy stem as we pass to
the higher forms, but in all cases the plant body has two
distinct and well-marked surfaces, an upper and an under
one, the latter bearing the root-hairs (rhizoids) by which
the plant is fixed to the ground. About 4000 species are
known.
427. Among the simplest of the Liverworts are the
little round, flat Riccias (Riccia) which grow on wet earth
or even float on the water. In the upper surface of the
loose green tissue are the sunken antherids which pro-
duce biciliated spiral sperms. In a similar manner the
archegones are sunken in the upper surface. After fer-
tilization the egg develops into a globose cellular body
HORXWORTS
245
(the sporophyte), whose interior cells divide into spores,
hut there are no " elaters." Although still surrounded by
the distended archegone this sporophyte is not organically
connected with any part of the gametophyte. The spores
escape by the decay of the surrounding layers of cells, and
on germination give rise to gametophytes like that with
which we started.
428. In the Horn worts (Anthoceros) the gametophyte
is a thin thallus of somewhat more compact tissue than
in Riccia, and growing on moist earth. The antherids
Fig. lis.— Rice
Fig. 119.
Anthoceros.
and archegones are sunken in the upper surface, and
resemble those of Riccia. When fertiUzed the egg de-
velops into an elongated, cylindrical sporophyte whose
upper part emerges from the neck of the archegone,
while the enlarged base remains seated in the venter.
The sporophyte is made up of a considerable mass of
green tissue, and is surrounded by an epidermis which is
suppUed with stomata like those of higher plants. This
the first appearance of true stomata in the Vegetable
Kingdom.
429. The lower part of the sporophyte continues to
grow in length indefinitely. Internally there is a layer
of cells by the division of which spores are formed, and
intermingled with these spores are the elongated sterile
cells called ''elaters. '' As the spores ripen above the
sporophyte splits from the top to permit their escape.
246
PHYLUAI VIII. BRYOPHYTA
Fig. 120. — Marchantia,
brood-masses (gemmae).
On germination the spores produce gametophytes like
the originals.
430. The verj^ conspicuous Great Liverwort (Mar-
chantia) is common on moist ground and is frequently
abundant in green houses. Its gametophyte is a large,
flat, branching, thalloid plant with a distinct midrib.
Its epidermis is pierced with circular, many-celled
''stomata" which open into large
air cavities supplied with many
green cells. Here and there on the
upper surface are cups containing
hairs whose terminal cells develop
into green masses (brood masses, or
gemmae) which fall off and quickly
develop into new gametophytes. This is thus an asex-
ual mode of reproduction, and these brood masses take
the place of the zoospores, tetraspores,
and conidia of lower plants.
431. The antherids are confined to par-
ticular portions of the gametophyte (an-
theridial disks) which are raised on short
stalks. Here they are sunken in the sur-
face and they and the sperms resemble
those of Riccia and Anthoceros.
432. The archegones are also confined to particular
portions of the gametophyte (known as '^ receptacles"
but really lobed disks) which are raised
on more or less elongated stalks (arche-
gonial branches). The archegones are
dependent from the under side of the re-
ceptacle. When fertilized the egg de-
velops into a globose, shortly stalked
sporophyte containing spores and elon-
gated sterile cells, the "elaters," whose walls are spirally
Fig. 121.— March-
antia (antherids).
Fig. 122.— March
antia (archegones)
SCALE MOSSES 247
thickened. By the expansive force of these elaters
the sporophyte is ruptured somewhat stellately, and the
spores are forced out. When the spores germinate they
give rise directly to the f!;ametophyte generation.
433. The Scale mosses (Order Jungermanniales)
are the highest of the Liverworts, and also the most
numerous in species. In the lower family {Metz-
gcriaccae) the gametophyte is usually a thal-
lus as in the liverworts already described,
but in the higher family {J linger manniaceae)
it is a creeping, leafy stem. In the first
f amity w^e find all gradations from the en- p^^ 12.3 —
tire margined thallus to those with more and- Metzgeria, and
^ Jungermanma.
more pronounced lateral lobing, and finally
to those in which the lobes have become distinct leaves
on a rounded stem. The leaves of Scale mosses are
but one cell thick and are not ribbed.
434. The antherids and archegones are borne dorsally
or subterminally and are much like those already
described. The sporophyte develops a slender stalk
which carries up the enlarged spore case, and the latter
when the spores are mature splits vertically into four
segments and permits the escape of spores and elaters.
When the spores germinate they may develop directly
such adult gametophytes as are described above, while
in the higher forms the gametophyte is first a filamentous
or thalloid structure ('^protonema") from which tlie
adult gametophyte subsequentl}^ buds out.
435. ALmy Scale mosses reproduce by means of l^rood
masses much like those of Marchantia, or even simple,
single-celled structures (brood cells).
436. Scale mosses have no stomata on either gameto-
phytes or sporophytes.
248 PHYLUM VIII. BRYOPHYTA
Laboratory Studies, (a) Look for Riccias on the wet
ground by the sides of ponds and slow streams from midsummer
to fall. Make careful vertical sections for structure of the
gametophyte, at the same time looking for the sexual organs
and the imbedded sporophyte.
(b) Study Anthoceros for gametophyte, and cylindrical spor-
ophj'tes. In the latter find stomata, spores and simple elaters.
Anthoceros may be obtained from the South (Gulf states) for
study in early spring.
(c) Collect specimens of the Great Liverwort (Marchantia)
which may be found in fruit in midsummer. Note that one
plant produces the antheridial branches, which have flat disks,
and another produces the archegonial branches, which have
lobed disks (''receptacles"). Note the cups, with contained
brood masses (gemmae).
(d) Examine the upper surface of a plant with a low power
of the microscope, and note the round ''stomata." Next strip
off some of the epidermis, mount in alcohol, and study with a
high power.
(e) Make longitudinal sections . of the plant through its
thickened central rib, and observe the elongated cells, with
foreshadow fibro-vascular bundles.
(/) Make vertical sections of the antheridial disk, mount in
water, and study the antherids. By repeated trials sperms
also may be seen.
(g) Make similar sections of the archegonial disk, and study
archegones. By taking older specimens the sporophytes,
spores, a
alcohol and afterward add a little potassium hydrate.
(h) Examine the bark of trees for small brownish Scale
mosses. Mount a bit of one in alcohol, afterward adding potas-
sium hydrate, and study for structure of the gametophyte.
In the spring the minute splitting spore cases may readily be
found.
Class MUSCI. Mosses
437. The gametophyte in this class is a leafy multi-
lateral stem, rarely bilateral. It is fixed to the soil or
other support by root-hairs (rhizoids) which grow out
from the sides of the stem. The leaves are usually
MOSSES 249
composed of a single layer of cells, and in many cases have
a midrib. The sporophyte is more or less elongated,
enlarged above into a spore-case (capsule) and does not
contain claters.
438. The tissues of the Mosses present a considerable
advance upon those of the Liverworts. In the stem
there is frequently a bundle of very narrow thin-walled
cells, which in some species become considerably thick-
ened. In a few cases there have been observed bundles
of thin-walled cells extending from the leaves to the
bundles in the stem. It cannot be doubted, then, that
the Mosses possess rudimentary fibro-vascular bundles.
As in liverworts, the tissues of mosses develop from
a single apical cell. Breathing-pores (stomata) re-
sembling those of the higher plants occur on the sporo-
phytes; they are not found upon the leaves or stems.
439. Mosses, for the most part, grow upon moist
earth or rocks, or upon the trunks and branches of
trees; comparatively few are
aquatic. They range in size from
less than a millimeter to many
centimeters in length, the most
common height being from 2 to 4
centimeters. They are all chlo- fig. 124.-A moss (protonema
rophyll-bearing plants, and are and leafy gamctophyte).
generally of a bright green color; occasionally, however,
they are whitish or brownish.
440. The reproduction of mosses is mainly sexual,
but often brood-masses are found resembling those of
liverworts. The sexual organs develop either upon the
ends of the main stems, within flower-like rosettes of
leaves, or on the ends of short branches in the axils of the
leaves.
441. The antherids are club-shaped or gloi)ose struc-
250 PHYLUiM VIII. BRYOPHYTA
tures whose interior cells produce sperms, which escape
from the antherid through a rent in its wall. Each
spermatogenous cell contains one spirally coiled sperm,
which, when set free, swims by means of its two long cilia.
442. The archegones are elongated, flask-shaped bodies
with a swollen base (''venter") and a long slender
neck. At maturity the neck has an open channel from
its apex to the base, where there is a rounded egg. In
some mosses the antherids and archegones are inter-
mixed in the same "flower," but in other cases they
occur upon different parts of the same plant ( monoe-
cious), or even upon different plants (dioecious).
Fig. 125. — Antherids and Fio. 126. — Archegones and eggs
sperms (Sphagnum and (Sphagnum and Funaria).
Funaria).
443. The act of fertilization requires water; but as the
sperms are very minute, a dewdrop may be suflacient.
The sperms swim to the open neck of the archegone,
down which they pass to the egg. The egg now begins
to divide rapidly, growing upward, eventually forming
the sporophyte. In most mosses the sporophyte is
narrow and elongated below, forming a stalk (seta)
which supports the upper spore-bearing part (the capsule
or spore-case). The epidermis of the latter is usually
provided with stomata, especially toward its basal part.
444. The spore-case, when ripe, usually opens by a
lid which falls off, leaving a round opening, generally
fringed with many teeth. In most species as the sporo-
I
ORDERS OF MOSSES 251
phyto elongates it carries up the remains of the distended
archegone as a Uttle cap (calyptra).
445. The spores, which are round or angular cells
containing protoplasm, chloroplasts, oil-drops, etc.,
germinate quickly upon moist soil. Each spore pro-
trudes a tubular filament, which develops into a conferva-
like ])ranching growth of green cells, called the '^pro-
tonema." Upon this buds are event uall}^ produced from
which spring up the leafy stems, thus completing the
round of life.
446. There are three orders of Mosses, including about
12,600 species, as follows: (1) Black Mosses (Order An-
dreas ales), composed of a few small and rare mosses
whose spore-cases open by four longitudinal slits; (2)
Peat-mosses (Order Sphagnales), composed of large,
soft and usually pale-colored plants, with clustered lat-
eral branches; they inhabit bogs and swamp}- places,
where they form dense moist cushions, often
of great extent. On account of pecuharities
in the structure of their leaves they are en-
abled to absorb and hold large quantities of
water, and for this reason they are exten-
sively used for "packing" in the transporta-
tion of living plants. They all belong to Fig. 127 —
the genus Sphagnum, and their spore-cases (Amirt
open by a circular lid, leaving an unguarded
opening (without teeth). In this and the preceding
order the stalk supporting the spore-case is an extension of
the gametophyte stc^n and not a part of the sporophyte.
447. (3) True Mosses (Order Bryales) include the
great majority of the species of this class. They are
usually bright green (in a few genera brownish), and in
most instances live upon moist ground and rocks, or
upon the bark of trees; in a comparatively small number
252 PHYLUM VIII. BRYOPHYTA
/^
of cases the species live in the water. They are undoubt-
edly the highest of the class, and show a greater differ-
entiation of tissues than either of the pre-
ceding orders. The spore-cases usually
r^ open by a circular lid (operculum), and
' V the opening is usually guarded by one or
_ two rows of teeth (the peristome) of which
Sporophytea there may be 4, 8, 16, 32 or 64. Here
(Bryales). ^ \ ^ i .
the seta is a part of the sporopnyte.
448. There are more than fifty families of True
Mosses, of which about one-half are Top Mosses
(Acrocarpi), i.e. bearing their sporophytes at the summit
of the gametophyte stem, the remainder being Side
Mosses (Pleurocarpi) , with laterally borne sporophytes.
Among the first are Turf Mosses (Dicranaceae) , Cushion
Mosses (Leucohryaceae) , Petticoat-mosses \>
(Splachnum) , Bristle Mosses {Funariaceae
and Timmiaceae) y Ephemeral Mosses {Ephe-
merum), Wood Mosses (Bryaceae and Mnia-
ceae), Humpback Mosses {Buxhaumiaceae) ,
and Hair-cap Mosses (Po^y^nc/iaceae) . Among Top " moss,
the Side Mosses are the Brook Mosses [b on-
tinalaceae), the Tree Mosses {Climaciaceae) , and the Bog
Mosses (Hypnaceae).
Laboratory Studies, (a) Collect several kinds of mosses in
fruit; some of these should be of large species. Note the
brownish root-hairs, the stem and leaves, the spore-fruit (sporo-
phyte) composed of a slender stalk (seta) bearing a spore-case,
the latter in some species covered by a membranous or hairy
cap (calyptra).
(6) Select a broad-leaved species. Mount a single leaf in
water, and examine with a lower power. Note that the leaf
is (generally) a single layer of cells, and that the midrib (if
present) is composed of elongated cells. Make cross- and
longitudinal sections of stems of the larger species, and note
that some of the cells are elongated and fiber-like.
LABORATORY STUDIES 253
(c) Place a spore-case under tlic microscope and examine
with a low power, noting the lid. Now remove the lid and
observe the teeth. The teeth may be studied still better by
splitting the spore-case from base to apex and then mounting
in alcohol, and afterward adding potassium hydrate: or the
lid may be removed and a transection of the si)ore-case made
just below the peristome, so as to show the latter from above.
In these specimens spores may be studied also.
{(I) Split a young spore-case and examine the external sur-
face of the lower part for breathing-pores, and note internally
the adjacent chlorophyll tissues, and the sporogenous layer
above.
(e) Collect a number of mosses not in fruit, showing at the
apex of their stems little cup-shaped whorls of leaves. IVIake
several vertical sections of one of these cups, and mount in
water. Examine for antherids and archegones. Sperms may
sometimes be seen with a high power.
(/) The first stage (protonema) of a moss gametopl\vte may
be found by scraping off some of the greenish growth from a wall
or cliff or surface of a greenhouse flower pot where yomig mosses
are just springing up. By mounting some of this in water and
washing awaj^ the dirt the branching green growth may
generally be seen, with here and there the buds which give rise
to leafy stems.
LITERATURE OF BRYOPHYTA
D. H. Campbell, The Structure and Development of Mosses and
Ferns, New York, 1905.
L. AI. Underwood, Descriptive Catalogue of the Xorth American
Hepaticae, Champaign, 1883.
L. Lesquereux and T. P. James, Manual of the Mosses of
North America, Boston, 1884.
A. J. Grout, Mosses with a Hand Lens and Microscope, Brook-
lyn, 1905-1911.
CHAPTER XV
PHYLUM IX. PTERIDOPHYTA*
THE FERNS
449. The Ferns are green plants that as to their
gametophytes are of smaller size than the INIossworts,
while, as to their sporophytes they are much larger and
more complex. In fact the gametophyte generation is
so small compared with the sporophyte that it is usually
overlooked, or when seen is often not recognized as a
fern at all by those who are not familiar with the whole
life cycle of these plants. The fern that we commonly
see with its roots, solid stems, and ample leaves is the
sporophyte generation, which has become so large and
conspicuous in this phylum that it completely over-
shadows the little gametophyte.
450. The gametophyte (commonly called the ''pro-
thallium") is usually a flat thallus, of
one or more layers of nearly uniform
chlorophyll-bearing cells, the whole
being rounded or heart-shaped in out-
line. Its longitudinal axis is consider-
FiG. 130.— Game- ably thickeued, and this portion is pro-
tophytes" 7 i i
vided underneath with many root-hairs,
intermingled with which in most cases are the antherids
and the archegones.
451. The antherids are nearly globular, few-celled
* This name is here used in the narrower sense excluding Cala-
mites and Lycopods.
254
FERN STRUCTURE
:oo
Fig. 131.— Fern arch-
1 r ,^ • , . , 1 egone, egg, antherid and
where one oi them unites with sperm.
structures consisting of an outer hi^-er of cells surrounding
a central mass of small cells, each of which produces
a sperm. When mature, the antherids rupture and
permit the escape of the spiral multiciliated sperms
which swim with a rotary motion.
452. The archegones are flask-shaped organs sunken
into the tissues of the plant. At first
the neck is closed, but at maturity it
opens down to the egg. Fertilization
takes place in water (after rains or
heavy dews), the sperms swimming
to and down the neck of the arche-
gone,
the egg.
453. Sporophyte. After fertilization the egg divides
again and again, soon producing a solid stem from which
a root springs at one end, while from the other the leaves
arise. The latter are at first small and quite simple in
structure, but those formed later are larger and more
and more complex in structure, until finally the full form
is reached, and still later the full
size. The stem, bearing leaves
and roots, constitutes the sporo-
phyte, which is sharply contrasted
with the gametophyte in structure,
size, and duration, the latter being
short-lived, small, and of simple
structure, while the former is long-lived, often of large
size, and of great complexity of structure. On this
plant the spores are eventually produced which on
germination give rise to gametophytes like those with
which we started, thus completing the round of life. In
most Ferns the spores are of one kind, only (isospores),
but in a few they are of two kinds (heterospores) in
Fig
132. — Development of
fern sporophyte.
256 PHYLUM IX. PTERIDOPHYTA
which some arc small (microspores) and the others large
(megaspores).
454. In looking over the whole structure of the Ferns
it will be seen that the sporophyte has become the
dominant generation. This is due to the fact that in
its development it has pushed roots of its own down into
the ground from its lower end, thus insuring a constant
supply of water, while at the same time it has pushed
out some of the green tissue from its upper part into flat
expansions (leaves), thus insuring the supply of car-
bohydrates. The sporophyte has thus become in-
dependent of the gametophyte, and the latter, being now
useless after the maturity and disappearance of the sexual
organs, has become very short-lived, while the rooted
and leafy sporophyte has developed into a long-lived
plant, which may continue its growth for many years.
455. With this longer life and larger size the fern
sporophytes have developed many kinds of tissues in
addition to parenchyma, including collenchyma, scler-
enchyma, fibrous tissue, tracheary tissue, and sieve
tissue, some of which appear to be as highly specialized
as in the flowering plants. Furthermore, true vascular
bundles as well as bundles of fibrous tissue are developed,
the roots containing bundles of the radial type, and the