13 feb. 2012ferns&moss.ppt1 ferns & mosses seedless plants

13 Feb. 2012 Ferns&Moss.ppt 1

FERNS & MOSSES

Seedless plants


Spore-dispersed plants• Seedless, dispersion by spores• Advantages of spores

– Cheap, each one small, requires small resource investment

– Produced in huge numbers

• Can result in huge numbers of offspring

• Disadvantage

– Wasteful, most spores unsuccessful

– Must land on good moist soil

– Little resource to support growing gametophyte


Spore-dispersed vascular plants

• Vascular tissues, = xylem, phloem– Allow growth to large size– Local ferns, horsetails, club mosses not very

large, fronds 30-40 cm– Tree ferns (tropical) to 18 m tall w/ fronds 3 m

long– Prehistoric club mosses tree-sized


Phylum Pterophyta (Ferns)


Phylum Pterophyta (Ferns)

• Leafy fronds, usually compound • Fronds grow as “fiddleheads”• Sporangia in sori under fronds • One kind of spores only

– homosporous • Gametophyte with both antheridia & archegonia

– Antheridia release sperm before archegonia mature!


Phylum Sphenophyta("horsetails" or "scouring rushes")

• Hollow, segmented stems• Minute bristle-like gray-brown fronds• Sporangia at tips of stems in strobilus• Heterosporous, two kinds of spores

– separate male & female gametophytes.• Stems hard, gritty with crystals of silica

(SiO2, sand, glass)


Phylum Sphenophyta


Phylum Lycophyta("club mosses" or "ground pine")

• Short stems with microphylls, – one vein per leaf (veins don’t branch)

• Sporangia at tips of stems or axils of fronds in strobilus

• Heterosporous, two kinds of spores– separate male & female gametophytes.


Phylum Lycophyta("club mosses" or "ground pine")


Spore-dispersed nonvascular plants

• Lack xylem or phloem– Limited ability to transport water, minerals,

sugars

• Usually live in moist places– Some can endure drying, metabolism

ceases until they are wet again.


Phylum Bryophyta(Mosses)

• Familiar, low green soft masses on ground, usually in moist places


Phylum Bryophyta(Mosses)

• Life Cycle (very different from ferns, etc.)– dominant GAMETOPHYTE (haploid)

• familiar form

• green, with tiny leaf-like blades,

– antheridia & archegonia at top of moss– zygote grows into SPOROPHYTE (diploid)

• = stalk + capsule

– Capsule dries, splits open, releases spores– Spores grow into GAMETOPHYTE


Moss Life Cycle


Economic uses of ferns, mosses

• Horticulture, landscaping

• Peat moss (Sphagnum)– soil conditioner, holds moisture,– cut, dried, burned as fuel in Ireland,

Scandinavia.


Formation of a peat bog

• Continental glacier plows up soil• Glacier breaks up as it melts back


Formation of a peat bog

• Hole left fills with meltwater• Sphagnum grows from edges, may

eventually fill bog

Economic uses of ferns, mosses

• Carboniferous Period (middle Paleozoic)– Ferns, tree ferns, tree-like

"horsetails," tree-like lycophytes fossilized

– Coal deposits

– Power for heavy industry, electrical generation



Origins of plants

• from some green algae – multicellular

– same photosynthetic pigments, chlorophyll a, b

– store food as starch

– cellulose cell walls

– alternation of generations


Evolution of plants

• One group includes mosses– dominant gametophyte

• 2nd group includes ferns, seed plants– Sporophyte dominant

– Vascular tissue


Evolution of plants• One group includes mosses, hornworts

– dominant gametophyte, non-vascular

• 2nd group includes ferns, seed plants– dominant sporophyte, vascular tissue


Challenges to terrestrial organisms (& how plants meet the challenges):

• 1. Getting water, water transport to cells– specialized vascular tissues

• 2. Evaporation, drying– waxes, oils in "epidermis," close stomata

• 3. Gravity, need for support– fluid pressure in vascular tissue;– lignified xylem = wood

• 4. Rapid temperature changes– evaporative cooling requires even more water!– seasonal: drop leaves or close stomata

13 feb. 2012ferns&moss.ppt1 ferns & mosses seedless plants

Documents

phylum lycophytaclub

phylum bryophytamossesfamiliar

phylum sphenophytahorsetails

phylum sphenophytafernsmoss

compound fronds

axils of fronds

large sizelocal ferns

economic uses of ferns