Ferns and Horsetails PDF

(Monilophyta) Monilophytes  1 Origin of land plants (about 475 mya) 2 Origin of vascular plants (about 420 mya) 3 Origin of extant seed plants (about 305 mya) Liverworts...

(Monilophyta) Monilophytes  1 Origin of land plants (about 475 mya) 2 Origin of vascular plants (about 420 mya) 3 Origin of extant seed plants (about 305 mya) Liverworts (bryophytes) plants Nonvascular Land plants ANCES- 1 Hornworts TRAL GREEN ALGA Mosses Lycophytes (club mosses, Vascular plants plants vascular Seedless spike mosses, quillworts) 2 Pterophytes (ferns, horsetails, whisk ferns) Gymnosperms Seed plants 3 Angiosperms 500 450 400 350 300 50 0 Millions of years ago (mya)  Comparing the taxa Bryophytes, Hornworts, Liverworts Seedless Land Plants Height limited by lack of Vascular tissues allow vascular tissues for larger, taller plants Flagellated sperm Flagellated sperm and usually in moist are usually restricted to environments moist environments Gametophytes are the Sporophytes are the dominant generation dominant generation  Fern gametophytes – Hermaphroditic – A few mm in size Image from Brian McCauley  What it means to be vascular Vascular tissue facilitates the transport of fluids (and hence nutrients) through the plant Xylem conducts most of the water and minerals and includes dead cells called tracheids Phloem consists of living cells and distributes sugars, amino acids, and other organic products Water-conducting cells are strengthened by lignin and provide structural support Image from Brian McCauley  Plant parts Roots are organs that anchor vascular plants They enable vascular plants to absorb water and nutrients from the soil Leaves are organs that increase the surface area of vascular plants, thereby capturing more solar energy that is used for photosynthesis – Lycophylls, leaves with a single vein – Euphylls, leaves with a highly branched vascular system  Roots and Things that are not Roots Not all underground structures are roots True Roots – Tap roots – large vertically growing root Examples: carrots, radish, parsnips – Tuberous roots – modified lateral roots for storage Examples: sweet potatoes, yams Modified stems – Corm – Rhizomes – Tuber Bulbs  Overtopping growth Megaphyll Vascular tissue Sporangia Microphyll Other stems Webbing become re- develops. duced and flattened. (a) Microphylls (b) Megaphylls  Sporophylls and Spore Variations Sporophylls are modified leaves with sporangia Sori are clusters of sporangia on the undersides of sporophylls Strobili are cone-like structures formed from groups of sporophylls Image from Brian McCauley Strobilus  More Spores Most seedless vascular plants are homosporous, producing one type of spore that develops into a bisexual (hermaphroditic) gametophyte All seed plants and some seedless vascular plants are heterosporous Heterosporous species produce megaspores that give rise to female gametophytes, and microspores that give rise to male gametophytes Homosporous spore production Typically a Eggs Sporangium Single bisexual on sporophyll type of spore gametophyte Sperm Heterosporous spore production Megasporangium Female Megaspore Eggs on megasporophyll gametophyte Microsporangium Male Microspore Sperm on microsporophyll gametophyte  Seedless vascular plants Phylum Lycophyta includes club mosses, spike mosses, and quillworts Phylum Pterophyta or Monilophyta includes ferns, horsetails, and whisk ferns and their relatives Carboniferous Forests  How we know what the past looked like Illinois coal mines – Forest floor is mine ceiling  306 mya Earthquake buried the site 4 square miles of forest/swamp revealed  Lycophytes (Phylum Lycophyta) 2.5 cm Isoetes Strobili gunnii, (clusters of a quillwort sporophylls) Selaginella apoda, a spike moss 1 cm Diphasiastrum tristachyum, a club moss  Ferns Second largest plant phyla after the angiosperms 12,000 species Relatively little economic impact – Invasive species – Limited food source – Horticulture – Toxic waste removal Horsetails Found on all continents except Asia and Australia 30 species in one genus today Very diverse in the Carboniferous – 30 m high trees Very limited economic importance Photo by Luc Viatour