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18 Sept. 2014 Ferns&Moss.ppt 2
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
18 Sept. 2014 Ferns&Moss.ppt 3
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)
• Leafy fronds, usually compound
• Fronds grow as “fiddleheads”
18 Sept. 2014 Ferns&Moss.ppt 5
Phylum Pterophyta (Ferns)• Sporangia in sori
under fronds • One kind of spores
only homosporous
• Gametophyte with both antheridia & archegonia Antheridia release
sperm before archegonia mature!
18 Sept. 2014 Ferns&Moss.ppt 6
18 Sept. 2014 Ferns&Moss.ppt 7
Phylum Sphenophyta("horsetails" or "scouring rushes")
• Hollow, segmented stems• Minute bristle-like gray-brown fronds• Stems hard, gritty with crystals of silica
(SiO2, sand, glass)
Phylum Sphenophyta
• Sporangia at tips of stems in strobilus
• Heterosporous, two kinds of spores separate male &
female gametophytes.
• One living genus Equisetum
18 Sept. 2014 Ferns&Moss.ppt 8
18 Sept. 2014 Ferns&Moss.ppt 9
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.
18 Sept. 2014 Ferns&Moss.ppt 11
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.
18 Sept. 2014 Ferns&Moss.ppt 12
Phylum Bryophyta(Mosses)
• Familiar, low green soft masses on ground, usually in moist places
18 Sept. 2014 Ferns&Moss.ppt 13
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 mosszygote grows into SPOROPHYTE (diploid)
• = stalk + capsule
• Capsule dries, splits open, releases spores
• Spores grow into GAMETOPHYTE
18 Sept. 2014 Ferns&Moss.ppt 15
Economic uses of ferns, mosses
• Horticulture, landscaping
• Peat moss (Sphagnum) soil conditioner, holds moisture, cut, dried, burned as fuel in Ireland,
Scandinavia.
18 Sept. 2014 Ferns&Moss.ppt 16
Formation of a peat bog
• Continental glacier plows up soil• Glacier breaks up as it melts back
18 Sept. 2014 Ferns&Moss.ppt 17
Formation of a peat bog
• Hole left fills with meltwater• Sphagnum grows from edges, may
eventually fill bog
Economic uses of ferns, mosses
18 Sept. 2014 Ferns&Moss.ppt 19
• Carboniferous Period (middle Paleozoic) Ferns, tree ferns, tree-like
"horsetails," tree-like lycophytes fossilized
Coal deposits Power for heavy industry,
electrical generation
18 Sept. 2014 Ferns&Moss.ppt 20
Origins of plants
• from some green algae • multicellular
• same photosynthetic pigments, chlorophyll a, b
• store food as starch
• cellulose cell walls
• alternation of generations
18 Sept. 2014 Ferns&Moss.ppt 21
Evolution of plants
• One group includes Bryophyta (mosses) Gametophyte dominant
• 2nd group includes ferns & seed plants, Lycophyta—Coniferophyta Sporophyte dominant Vascular tissue
18 Sept. 2014 Ferns&Moss.ppt 22
Evolution of plants• One group includes mosses, hornworts
dominant gametophyte, non-vascular
• 2nd group includes ferns, seed plants dominant sporophyte, vascular tissue
18 Sept. 2014 Ferns&Moss.ppt 23
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