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

tallFern 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.

FIDDLE HEADS

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 rustsSori of some species are covered by an outgrowth from the leaf

surface called indisiumMost 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 cycleFern’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 archegoniaZoom 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 branchingsporangia dense on specialized slender lobes of the

ultimate segmentsmostly tropical

FAMILY: SchizaeaceaeGENUS: Schizaea

Kingdom: PlantaeDivision: Pteridophyta

Class: PolypodiopsidaOrder: SchizalesFamily: Schizaeaceae

Genus: Schizaea

FAMILY: SchizaeaceaeGENUS: Schizaea

Common names: curly grass and comb fernSome species are very small and inconspicuous, and so

may often be overlooked in natureThe genus is distinctive and not at all like the common

conception of a fern

Schizaea pectinata

FAMILY: SchizaeaceaeGENUS: 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.

Actinostachys laevigata

FAMILY: Thelypteridaceae

plants in soil or, less commonly, on rocksrhizomes short- to long-creeping or erect, scalyleaves 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

FAMILY: ThelypteridaceaeGENUS: Thelypteris


Class: PolypodiopsidaOrder: PolypodialesFamily: Thelypteridaceae Genus: Thelypteris

FAMILY: ThelypteridaceaeGENUS: 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

Thelypteris palustris

FAMILY: ThelypteridaceaeGENUS:Phegopteris


Class: PolypodiopsidaOrder: ArthyrialesFamily: Thelypteridaceae Genus: Phegopteris

Phegopteris connectilis

FAMILY: Dicksoniaceae

tree fern familystems 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.)

FAMILY: Dicksoniaceae GENUS: Dicksonia


Class: PolypodiopsidaOrder: CyathealesFamily: Dicksoniceae Genus: Dicksonia

FAMILY: Dicksoniaceae 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

Dicksonia fibrosa

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 liverwortsmostly rainforest epiphytesspores globose, greengametophyte ribbon-shaped or filamentous

FAMILY: Hymenophyllaceae GENUS: Hymenophyllum


Class: PolypodiopsidaOrder: HymenophyllalesFamily: Hymenophyllaceae Genus: Hymenophyllum

FAMILY: Hymenophyllaceae 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

Hymenophyllum tunbrigense

FAMILY: Hymenophyllaceae GENUS: Trichomanes


Class: PolypodiopsidaOrder: HymenophyllalesFamily: Hymenophyllaceae Genus: Trichomanes

FAMILY: Hymenophyllaceae GENUS: Trichomanes

termed bristle fernsleaf tissue typically 2 cells thickthe name bristle fern refers to the small bristle that

protrudes from the indusia of these ferns

Trichomanes radicans

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 lobeddistributed nearly worldwide but most diverse in tropical

regions

FAMILY: BlechnaceaeGENUS: Blechnum


Class: PolypodiopsidaOrder: PolypodialesFamily: Blechnaceae Genus: Blechnum

FAMILY: BlechnaceaeGENUS: Blechnum

“hard fern”greatest species diversity is in tropical regionsmost are herbaceous plants, but a few species are tree

ferns with stems up to 3 m tallvaries from most ferns in having a separation of sterile

(photosynthetic) and fertile (reproductive) fronds in the same plant.

Blenchum brasiliense

FAMILY: Cyatheacea

scaly tree fern familystems erect and mostly trunklike (up to 25 m. or 82 ft.)scaly near the tip (sometimes also hairy) and usually with

a mantle of rootsleaves mostly large (up to 5 m. or about 16 ft.), one to

four times pinnately compound

FAMILY: CyatheaceaGENUS: Cyathea


Class: PolypodiopsidaOrder: CyathealesFamily: Cyatheaceae Genus: Cyathea

FAMILY: CyatheaceaGENUS: Cyathea

terrestrial ferns, usually with a single tall stemrarely, the trunk may be branched or creepingmany species also develop a fibrous mass of roots at the

base of the trunkhabitats ranging from tropical rain forests to temperate

woodlands

Cyathea

FAMILY: Aspleniaceae

“spleenworts”plants in soil, on rocks, or epiphyticrhizomes 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


Class: PolypodiopsidaOrder: PolypodialesFamily: Aspleniaceae Genus: Asplenium

Asplenium

FAMILY: Dennstaedtiaceae

“cup ferns” and “bracken”mostly in soil, occasionally climbingrhizomes mostly very long-creeping (to more than 100 m.

or 330 ft.), in Pteridium), hairyleaves two to four times pinnately compound, glabrous

or hairy

FAMILY: DennstaedtiaceaeGENUS: Pteridium

Kingdom: Plantae

Division: PteridophytaClass: PolypodiopsidaOrder: Dennstaedtiales

Family: DennstaedtiaceaeGenus: Pteridium

FAMILY: DennstaedtiaceaeGENUS: Pteridium

“bracken”noted for their large, highly divided leavesthe world's most abundant fern

Pteridium aquilinum

FAMILY: Salviniaceae

heterosporous fernsfloating fernsmostly appearing dichotomously branched, sometimes

lacking rootsdistributed nearly worldwide but most diverse in the

tropics.

FAMILY: SalviniaceaeGENUS: Salvinia


Class: PolypodiopsidaOrder: SalvinialesFamily: Salviniaceae

Genus: Salvinia

FAMILY: SalviniaceaeGENUS: Salvinia

“watermoss”small, floating aquatics with creeping stems, branched,

bearing hairs on the leaf surface papillae but no true rootsleaves 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

Salvinia minima

FAMILY: SalviniaceaeGENUS: Azolla


Class: PolypodiopsidaOrder: SalvinialesFamily: Salviniaceae

Genus: Azolla

FAMILY: SalviniaceaeGENUS: 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

Azolla filiculoides

FAMILY: Marsileaceae

"pepperwort family" or "water-clover family"heterosporousaquatic and semi-aquatic ferns, though at first sight they

do not physically resemble other ferns

FAMILY: MarsileaceaeGENUS: Marsilea


Class: PolypodiopsidaOrder: SalvinialesFamily: Marsileaceae

Genus: Marsilea

FAMILY: MarsileaceaeGENUS: Marsilea

aquatic fernsunusual 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.

Marsilea

USESsome ferns species are edible, with crosiers being

considered delicaciesOther ferns are used medicinallyby contrast, Osmunda and Pteridium ferns are

considered to be carcinogenic (any substance or agent that tends to produce a cancer)

USESthe 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

USESthe 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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