Phylum Pteridophyta (True Ferns) - part 2

Pterophyta
(True Ferns)
SYNONYMS: PTERIDOPHYTA;
FILICOPHYTA

STRUCTURE and FORM
approximately 11,000 known species
Vary in size from less than 1 cm in diameter to 25 meters
tall
Fern leaves are megaphylls that are commonly referred
to as fronds

STRUCTURE and FORM
Some are undivided, pleated or tongue-like, and others
resemble four-leaf clover or grow in such a way as to form
“nests”
Most abundant in wetter tropical and temperate habitats
but few are adapted to drier areas

STRUCTURE and FORM
Early leaves are lopsided because they grow faster on
their lower surface than their upper surface. This growth
pattern, which is called circinate vernation, produces
young leaves that are coiled into “fiddle heads.”
These croziers or “fiddle heads” the unroll and expand
revealing the blades.
Fern leaves are usually fertile but do not form strobili.

STRUCTURE and FORM
Sorus- dark spots on the lower surface of fern leaves which is
actually a collection of sporangia
These patches appear similar to fungal rusts
Sori of some species are covered by an outgrowth from the
leaf surface called indisium
Most modern ferns are homosporous (two orders of water
ferns and some extinct ferns are heterosporous).

A and B. Cross-section through a
leaflet of a true fern
1 = frond, 2 = vascular bundle, 3
= sorus, 4 = indusium (protective
scale), 5 = sporangia, 6 =
sporangium wall, 7 = spores
C. Detail of an entire spore
D. Detail of section through
spores.
E. Detail of the wall of a spore

STRUCTURE and FORM
The more primitive species have a protostele, most have
siphonosteles, and some have complex dictyosteles.
Stems, for the most part, are rhizomes that grow at, or
just under, the ground surface.
Roots are simple, uncomplicated and arise adventitiously
along the rhizomes near the base of the fronds.

STRUCTURE and FORM
Ferns are divided into two groups based on the kind of
sporangium they possess. The more primitive are the
eusporangiate, and the more advanced the
leptosporangiate.
Eusporangia: These sporangia are thick‐walled and open
by splitting transversely. They produce thousands of
spores.

STRUCTURE and FORM
Leptosporangia: These thin‐walled, delicate sporangia
are only one or a few layers thick. They have an area,
the annulus, where cell walls are thickened. When the
annulus cells dry out at maturity, the sporangium splits
and, like a catapult, throws out the spores.
Spores are few—128 at most, but commonly 64.

REPRODUCTION
Sporophyte – is the conspicuous phase of the life cycle
Fern’s sporophyte consist of the fronds, a stem in the
form of a rhizome, and adventitious roots that arise along
the rhizome.

Young sporophyte
and gametophyte

REPRODUCTION
At maturity, the blades are often divided into segments
called pinnae that are attached to a midrib or rachis.
A stalk or petiole is usually present at the base.
Sori appear on the lower surfaces of blades of a mature
fronds.

REPRODUCTION
o These patches are actually clusters of sporangia.
oThese are mostly found in numerous, discrete clusters
called sori (singular:sorus)
oThe sori are protected by thin, individual flaps of colorless
tissue called indusia (singular:indusium)
oThis indisium often resembles a tiny, semi-transparent
umbrella attached to its base to the frond surface

REPRODUCTION
oAs sporangia mature, the indisium, resembles shrivels and
exposes the sporangia beneath.
Most sporangia have a conspicuous row of heavy-walled
brownish cells along the edge. This row of cells is called
annulus which looks like a tiny millipede.
Annulus functions in catapulting spores out of the
sporangium.

REPRODUCTION
Annulus functions in catapulting spores out of the
sporangium.
Sporocytes undergo meiosis in the sporangia producing
either 48 or 64 spores per sporangium
After the spores have been flung out of their sporangia,
they are dispersed by the wind

REPRODUCTION
Shady, wet ledges and rock crevices or moist soil are
habitats usually suitable for their survival
Those that germinate in favorable locations produce little
“Irish valentines” or prothalli as the green, heart-shaped
gametophytes of ferns and other seedless vascular plants
Prothalli are only one cell thick except the middle which
is slightly thicker

1 = young prothallium, 2 = rest of the spore wall, 3 = chloroplasts, 4 = rhizoids

REPRODUCTION
Antheridia are interspersed among the rhizoids produced
on the lower surface of the central area with archegonia
are also being produced, usually closer to the notch of the
heart-shaped gametophyte.
Archegonia – flask-shaped with curving necks that
protrude slightly above the surface

A - D. Prothallium with
antheridia.
Zoom view of antheria
and sperms.
A and B. 1 = antheridia,
2 = sperms in the
antheridia
C. Detail of sperms
(with flagella)
D. Detail of antheridia
filled up with sperms

A - D. Prothallium with archegonia
Zoom view of prothallium, archegonia
and egg cell
A. Prothallium with archegonia
B. Detail of archegonium in a cross-
section (zoom of archegoniuma, egg
cell)
C. Detail of archegonia in upperview
D. Detail of prothallium cells
(photosynthetic active due to
chloroplasts)
1 = prothallium, 2 = prothallium cells, 3
= rhizoids, 4 = archegonia, 5 = egg cell, 6
= neck canal cells, 7 = neck canal, 8 =
chloroplasts inside prothallium cells, 9 =
cell nucleus

FAMILY: Schizaeaceae
leaves more or less grasslike, with a long petiole and a
linear or fan-shaped blade
veins dichotomously branching
sporangia dense on specialized slender lobes of the
ultimate segments
mostly tropical

GENUS: Schizaea
Kingdom: Plantae
Division: Pteridophyta
Class: Polypodiopsida
Order: Schizales
Family: Schizaeaceae
Genus: Schizaea

GENUS: Schizaea
Common names: curly grass and comb fern
Some species are very small and inconspicuous, and so
may often be overlooked in nature
The genus is distinctive and not at all like the common
conception of a fern

GENUS: Actinostachys
small genus of small ferns originally included in the genus
Schizaea
was segregated on the basis of the flabelliform (fan-
shaped) laminae
colloquially called the ray ferns.

FAMILY: Thelypteridaceae
plants in soil or, less commonly, on rocks
rhizomes short- to long-creeping or erect, scaly
leaves mostly one or two times pinnately divided, rarely
highly divided, most commonly with slender needlelike
hairs
sori round or elongate along the veins, the indusia absent
or kidney-shaped

GENUS: Thelypteris
Kingdom: Plantae
Order: Polypodiales
Family: Thelypteridaceae
Genus: Thelypteris

GENUS: Thelypteris
“maiden ferns”
terrestrial, with the exception of a few which are
lithophytes (grow on rocks)
hese ferns are tropical, although there are a number of
temperate species

GENUS:Phegopteris
Kingdom: Plantae
Order: Arthyriales
Family: Thelypteridaceae
Genus: Phegopteris

FAMILY: Dicksoniaceae
tree fern family
stems mostly erect and trunklike (up to 10 m or 33 ft.) or,
less commonly, smaller, hairy near the tip and usually
with a mantle of roots
leaves, which are often highly divided (up to 3.5 m. or
11.5 ft.)

GENUS: Dicksonia
Kingdom: Plantae
Order: Cyatheales
Family: Dicksoniceae
Genus: Dicksonia

GENUS: Dicksonia
regarded as related to Cyathea, but is considered more
primitive
fossil record includes stems, pinnules, and spores.
An easily cultivated species of Dicksonia is D. antarctica,
the soft tree fern

FAMILY: Hymenophyllaceae
“filmy ferns” and “bristle ferns”
often appear as very dark green or even black clumps
and may be mistaken for a robust moss or liverworts
mostly rainforest epiphytes
spores globose, green
gametophyte ribbon-shaped or filamentous

GENUS: Hymenophyllum
Kingdom: Plantae
Order: Hymenophyllales
Family: Hymenophyllaceae
Genus: Hymenophyllum

GENUS: Hymenophyllum
its name means "membranous leaf", referring to the very
thin translucent tissue of the fronds
leaves are generally only one cell thick and lack stomata,
making them vulnerable to desiccation
found only in very humid areas, such as in moist forests
and among sheltered rocks

GENUS: Trichomanes
Kingdom: Plantae
Order: Hymenophyllales
Family: Hymenophyllaceae
Genus: Trichomanes

GENUS: Trichomanes
termed bristle ferns
leaf tissue typically 2 cells thick
the name bristle fern refers to the small bristle that
protrudes from the indusia of these ferns

FAMILY: Blechnaceae
plants in soil or on rocks, less commonly epiphytic, rarely
climbing
rhizomes short- to long-creeping or erect (occasionally
trunklike), scaly
leaves one time pinnately compound or lobed
distributed nearly worldwide but most diverse in tropical
regions

FAMILY: Blechnaceae
GENUS: Blechnum
Kingdom: Plantae
Order: Polypodiales
Family: Blechnaceae
Genus: Blechnum

FAMILY: Blechnaceae
GENUS: Blechnum
“hard fern”
greatest species diversity is in tropical regions
most are herbaceous plants, but a few species are tree
ferns with stems up to 3 m tall
varies from most ferns in having a separation of sterile
(photosynthetic) and fertile (reproductive) fronds in the
same plant.

FAMILY: Cyatheacea
scaly tree fern family
stems erect and mostly trunklike (up to 25 m. or 82 ft.)
scaly near the tip (sometimes also hairy) and usually with
a mantle of roots
leaves mostly large (up to 5 m. or about 16 ft.), one to
four times pinnately compound

FAMILY: Cyatheacea
GENUS: Cyathea
Kingdom: Plantae
Order: Cyatheales
Family: Cyatheaceae
Genus: Cyathea

FAMILY: Cyatheacea
GENUS: Cyathea
terrestrial ferns, usually with a single tall stem
rarely, the trunk may be branched or creeping
many species also develop a fibrous mass of roots at the
base of the trunk
habitats ranging from tropical rain forests to temperate
woodlands

FAMILY: Aspleniaceae
“spleenworts”
plants in soil, on rocks, or epiphytic
rhizomes short- to long-creeping or erect, usually scaly,
the scales usually clathrate (the cells with dark adjoining
walls and clear lateral walls)
the spores are mostly bean-shaped (bilateral)

FAMILY: Aspleniaceae
GENUS: Asplenium
Kingdom: Plantae
Order: Polypodiales
Family: Aspleniaceae
Genus: Asplenium

FAMILY: Dennstaedtiaceae
“cup ferns” and “bracken”
mostly in soil, occasionally climbing
rhizomes mostly very long-creeping (to more than 100 m.
or 330 ft.), in Pteridium), hairy
leaves two to four times pinnately compound, glabrous
or hairy

GENUS: Pteridium
Kingdom: Plantae
Order: Dennstaedtiales
Family: Dennstaedtiaceae
Genus: Pteridium

GENUS: Pteridium
“bracken”
noted for their large, highly divided leaves
the world's most abundant fern

FAMILY: Salviniaceae
heterosporous ferns
floating ferns
mostly appearing dichotomously branched, sometimes
lacking roots
distributed nearly worldwide but most diverse in the
tropics.

GENUS: Salvinia
Kingdom: Plantae
Order: Salviniales
Family: Salviniaceae
Genus: Salvinia

GENUS: Salvinia
“watermoss”
small, floating aquatics with creeping stems, branched,
bearing hairs on the leaf surface papillae but no true
roots
leaves are in trimerous whorls, with two leaves green,
sessile or short-petioled, flat, entire, and floating, and one
leaf finely dissected, petiolate, rootlike, and pendent

GENUS: Azolla
Kingdom: Plantae
Order: Salviniales
Family: Salviniaceae
Genus: Azolla

GENUS: Azolla
“mosquito fern, duckweed fern, fairy moss”
extremely reduced in form and specialized, looking
nothing like other typical ferns but more
resembling duckweed or some mosses

FAMILY: Marsileaceae
"pepperwort family" or "water-clover family"
heterosporous
aquatic and semi-aquatic ferns, though at first sight they
do not physically resemble other ferns

GENUS: Marsilea
Kingdom: Plantae
Order: Salviniales
Family: Marsileaceae
Genus: Marsilea

GENUS: Marsilea
aquatic ferns
unusual appearance and do not resemble common ferns
“water clover” or “four-leaf clover” because the long-
stalked leaves have four clover-like lobes and are either
held above water or submerged.

USES
some ferns species are edible, with crosiers being
considered delicacies
Other ferns are used medicinally
by contrast, Osmunda and Pteridium ferns are considered
to be carcinogenic (any substance or agent that tends to
produce a cancer)

USES
the aquatic mosquito fern (Azolla) hosts Anabaena
azollae, which converts nitrogen for use by plants such as
rice, enhancing production in rice paddies and other
fields
animals often root for fern rhizomes, which store
starches

USES
the braken fern Pteris vittata absorbs arsenic, a
carcinogenic heavy metal, from soil. By removing this
toxin, ferns can restore contaminated areas into viable
agricultural, industrial, and recreational sites.
ornamental garden plants and houseplants

Phylum Pteridophyta (True Ferns) - part 2

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