13 Feb. 2012Ferns&Moss.ppt1 FERNS & MOSSES Seedless plants

13 Feb. 2012Ferns&Moss.ppt2 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

13 Feb. 2012Ferns&Moss.ppt3 Spore-dispersed vascular plants Vascular tissues, = xylem, phloem –Allow growth to large size –Local ferns, horsetails, club mosses not very large, fronds cm –Tree ferns (tropical) to 18 m tall w/ fronds 3 m long –Prehistoric club mosses tree-sized

13 Feb. 2012Ferns&Moss.ppt4 Phylum Pterophyta (Ferns)

13 Feb. 2012Ferns&Moss.ppt5 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!

13 Feb. 2012Ferns&Moss.ppt6 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 (SiO 2, sand, glass)

13 Feb. 2012Ferns&Moss.ppt7 Phylum Sphenophyta

13 Feb. 2012Ferns&Moss.ppt8 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.

13 Feb. 2012Ferns&Moss.ppt9 Phylum Lycophyta ("club mosses" or "ground pine")

13 Feb. 2012Ferns&Moss.ppt10 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.

13 Feb. 2012Ferns&Moss.ppt11 Phylum Bryophyta (Mosses) Familiar, low green soft masses on ground, usually in moist places

13 Feb. 2012Ferns&Moss.ppt12 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

13 Feb. 2012Ferns&Moss.ppt13 Moss Life Cycle

13 Feb. 2012Ferns&Moss.ppt14 Economic uses of ferns, mosses Horticulture, landscaping Peat moss (Sphagnum) –soil conditioner, holds moisture, –cut, dried, burned as fuel in Ireland, Scandinavia.

13 Feb. 2012Ferns&Moss.ppt15 Formation of a peat bog Continental glacier plows up soil Glacier breaks up as it melts back

13 Feb. 2012Ferns&Moss.ppt16 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 13 Feb. 2012Ferns&Moss.ppt17

13 Feb. 2012Ferns&Moss.ppt18 Origins of plants from some green algae –multicellular –same photosynthetic pigments, chlorophyll a, b –store food as starch –cellulose cell walls –alternation of generations

13 Feb. 2012Ferns&Moss.ppt19 Evolution of plants One group includes mosses –dominant gametophyte 2nd group includes ferns, seed plants –Sporophyte dominant –Vascular tissue

13 Feb. 2012Ferns&Moss.ppt20 Evolution of plants One group includes mosses, hornworts –dominant gametophyte, non-vascular 2nd group includes ferns, seed plants –dominant sporophyte, vascular tissue

13 Feb. 2012Ferns&Moss.ppt21 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