Moss & Fern

Mosses & Ferns

Kingdom Plantae
All Materials © Cmassengale   

Seedless Nonvascular Plants

• Includes mosses, liverworts, and hornworts
• Lack vascular tissue (xylem & phloem) to carry water & food
• Have a Sporophyte & Gametophyte stage known as alternation of generations
• Gametophyte is dominant stage
• Reproduce by spores

Division  Bryophyta

 Mosses:

• Small, nonvascular land plants
• No true roots, stems, or leaves
• Class Musci
• Most common bryophyte
• Grow on moist areas (brick walls, as thick mats on forest floors, and on the shaded side of trees)
• Some can survive periodic dry spells & revive when H2O becomes available
• Must grow close together and must have H2O to complete their life cycle 
• Sperm swims to egg through drops of water during fertilization
• H2O moves cell-to-cell by osmosis
• Sphagnum moss is known for its moisture holding capacity, absorbing up to 20 times its dry weight with water.

MOSS SPOROPHYTES & FERN GAMETOPHYTES

LIFE CYCLE OF MOSSES:

• Mosses alternate between a haploid (n) gametophyte stage & a diploid (2n) sporophyte stage 
• Gametophyte is the dominant generation

• Called alternation of generations

• The haploid gametophyte stage contains half the chromosome number & produces gametes (egg & sperm) 
• Gametophyte stage is dominant in the moss’s life cycle
• Gametophytes are photosynthetic & have root-like rhizoids
• The diploid sporophyte has a complete set of chromosomes & produces spores by meiosis
• Sporophyte of a moss is smaller than, & attached to the Gametophyte
• Sporophytes lack chlorophyll & depend on the photosynthetic gametophyte for food
• Sporophyte has a long, slender stalk topped with a capsule
• Capsule forms haploid (n) spores 

Moss Capsules

Sexual Reproduction in Moss:

• Mosses produce 2 kinds of gametes (egg & sperm)
• Gametes of Bryophytes are surrounded by a jacket of sterile cells that keep the cells from drying out
• Female gametes or eggs are larger with more cytoplasm & are immobile
• Flagellated sperm must swim to the egg through water droplets for fertilization
• Moss gametes form in separate reproductive structures on the Gametophyte — Archegonium & Antheridium

• Each Archegonium forms one egg, but each Antheridium forms many sperm
• Fertilization can occur only after rain when the Gametophyte is covered with water
• Sperms swim to the egg by following a chemical trail released by the egg 
• A zygote (fertilized egg) forms that undergoes mitosis and becomes a Sporophyte
• Cells inside mature Sporophyte capsule undergoes meiosis and form haploid spores
• Haploid spores germinate into juvenile plants called protonema
• Protonema begin the Gametophyte generation

Protonema

• Spores are carried by wind & sprout on moist soil forming a new Gametophyte

Asexual reproduction in Mosses:

• Asexual reproduction in moss may occur by fragmentation or gemmae
• Pieces of a Gametophyte can break off & form new moss plants (fragmentation)
• Gemmae are tiny, cup shaped structures on the Gametophytes 
• Raindrops separate gemmae from the parent plant so they can spread & form new Gametophytes

Uses for Moss:

• Help decomposer dead logs
• Serve as pioneer plants on bare rock or ground
• Help prevent erosion
• Provide shelter for insects & small animals
• Used as nesting materials by birds & mammals
• Sphagnum or peat moss forms peat bogs (wet ecosystem)
• Peat is burned as fuel in some areas

Division  Hepatophyta  

Liverworts:

• Nonvascular
• Undergo alternation of generations with Sporophyte attached to Gametophyte
• Gametophytes are green & leafy and the dominant generation

Liverwort

• Need abundant water for fertilization
• Reproduce by spores
• Grow on moist rocks or soil
• Reproduce asexually by gemmae and by growing new branches

Division  Anthocerophyta

Hornworts:

• Small, nonvascular bryophytes
• Gametophyte leafy like liverworts
• Archegonia & antheridia form inside the plant
• After fertilization, zygotes develop into long, horn-shaped Sporophytes
• Horn-shaped Sporophytes capable of photosynthesis so not completely dependent on Gametophyte

Hornwort

Seedless Vascular Plants

• Includes club mosses, whisk ferns, horsetails, & ferns
• Have specialized vascular tissues (xylem & phloem) to transport H2O, food, etc.
• Have a Sporophyte & Gametophyte stage known as alternation of generations
• Sporophyte is the dominant stage
• Reproduce by spores

Division  Psilophyta

Whisk Ferns:

• Photosynthetic, aerial stem forks repeatedly to form a small twiggy bush
• No true roots, stems, or leaves
• Have horizontal, underground stems called rhizomes
• Root-like structures called rhizoids anchor plant
• Reproduce by spores & vegetatively from rhizomes
• Only 2 living genera

Whisk Fern

Division  Lycophyta

Club Mosses:

• Low growing plants resembling pine trees
• Have a club-shaped spore producing structure

Club Moss

• Some like Lycopodium contain chemicals that burn quickly
• Resurrection moss is green (after rains) when moist and brown when dry.

Division  Sphenophyta

Horsetails:

• Equisetum called scouring rush is the only living species
• Photosynthetic aerial stems & underground rhizomes
• Stems contain silica & were once used to scrub pots
• Reproduce by means of spores made in small cones at the tip of branches
• In prehistoric times, some plants of this family grew to be large trees
• Found in wetlands

Horsetail

Division  Pterophyta

Fern Gametophyte:

• Largest group of living seedless vascular plants
• Live in moist habitats
• Alternates between dominant Sporophyte stage & Gametophyte stage
• Sporophyte stage has true roots, stems, & leaves
• Produce spores on the underside of leaves 

• Leaves are called fronds & are attached by a stem-like petiole

FERNS

Fern Life Cycle:

• Spores produced on underside of fronds in clusters of sporangia called sori
• Spores undergo meiosis, are spread by wind, & germinate on moist soil to form prothallus
• Prothallus begins the Gametophyte stage
• Mature Gametophytes are small, heart-shaped structures that live only a short time
• Male antheridia & female archegonia grow on the prothalli
• Sperm must swim to the egg to fertilize it & developing embryo becomes the Sporophyte generation
• Newly forming fronds are called fiddleheads & uncurl

Uses for Ferns:

• Prevent erosion
• Fiddleheads serve as food
• Ornamental plants
• Formed coal million of years ago