Angiosperms Or Flowering Plants the Phylum Magnoliophyta
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Angiosperms or Flowering Plants! Land Plant Evolution: Algae to Angiosperms the phylum Magnoliophyta! The greatest adaptive radiation . • is the largest radiation of plants • involves series of dramatic adaptations to the problem of life on land and being non- motile • exhibits successive rounds of speciation and subsequent extinction • sets the stage for the development of a land-based ecosystem with fungi and animals Angiosperms - Flowering Plants! Fungi? ! • Fungi collectively are not a natural group Angiosperms focus of the course • More closely related to animals than to plants • comprise the phylum Magnoliophyta • vast majority of plant diversity What are the non-angiosperm land plants? • DNA evidence has clarified much but not all of the relatioships of other phyla (= divisions) See first pages of Chpts 1 & 3 for more detail (Plant Systematics) 1 Fungi? ! Fungi? ! Turning the Crown Upside Down: Gene Tree Parsimony Roots the Eukaryotic Tree of Life Traditional view of eukaryotic relationships Katz et al. 2012 Fungi are here Green Plants are here Systematic Biology Charales - stoneworts! Extinct Land Plants - the first plants Ordovician Period (505 - 440 mya) • Green algal lineage • First evidence of land life at 460 mya • Closest relatives to land plants Microfossils of spores with sporopollenin (degradation resistant material like lignin) and similar to modern day bryophytes such as liverworts Found worldwide in shales that were deposited at the marine-terrestrial interface 2 bryophytes! bryophytes! • earliest land plants - non vascular • gametophyte dominant, 16000 species • 3 lineages — they are not a natural group hornworts mosses mosses Liverworts - Marchantiophyta Mosses - Bryophyta Hornworts - Anthoceratophyta liverworts liverworts Extinct Land Plants - first vascular plants Lycopodiophyta - club mosses! Early Devonian Period (410 - 390 mya) • 3 families, 1150 species Rhynia seen in the early Devonian (Rhynie • sporophyte dominant, vascular, free sporing Chert fossil) is one of first vascular plants • they are sister to all other vascular plants 20 cm tall, no roots, no leaves, primitive vascular tissue Lycopodium - club mosses Isoetes - quillworts Selaginella - spike mosses 3 Extinct Land Plants - the first ferns Polypodiophyta - ferns! Late Devonian Period (390 - 360 mya) • 11000 species • immense variation in habit and habitat • spores produced in specialized sporangia • need a lot of systematic work - tropics! First true ferns [Protopteridium] - free sporing with complex sporangia & megaphylls Polypodiophyta - ferns! Polypodiophyta - ferns! • includes the horsetails as unusual ferns! • includes the strange whish ferns! • 15 species in Equisetum • 6 species in 2 genera • vascular plants, reduced leaves, terminal • vascular plants, leafless green stemmed, sporangia lateral sporangia Psilotum habit Psilotum branch Psilotum sporangia 4 Extinct Land Plants - the seed plants Extinct Land Plants – first gymnosperms Late Devonian Period (390 - 360 mya) Permian Period (286 - 245 mya) First “seeds” - “seed ferns” [Archaeosperma] Plants fern-like with dissected compound leaves, but produce naked seeds (embryo within • Big trees with net-veined protective coverings) leaves • Seed bearing (derived from female gametophyte) and pollen forming (from male gametophyte) Pinophyta - gymnosperms! Pinophyta - gymnosperms! • 870 species • 870 species • seed plants but seeds naked • seed plants but seeds naked • often divided into 4 phyla conifers • often divided into 4 phyla • is one closer to angiosperms? • is one closer to angiosperms? cycads pine spruce juniper male strobilus female strobili 5 Pinophyta - gymnosperms! Pinophyta - gymnosperms! • 870 species • 870 species • seed plants but seeds naked • seed plants but seeds naked • often divided into 4 phyla • often divided into 4 phyla • is one closer to angiosperms? • is one closer to angiosperms? gnetophytes mature seeds ginkgo Gnetum Ephedra male strobili Welwitschia mirabilis Extinct Land Plants – first flowering plants Magnoliophyta - angiosperms! Cretaceous Period (146 - 65 mya) Near the Jurassic/Cretaceous border, the first Angiosperms are seen • 275,000 + species • seed plants with seeds encased in ovary Triassic • flowers a “key innovation” Archaefructus 6 Angiosperms - Flowering Plants! Angiosperms - Flowering Plants! • tremendous adaptive radiation on • tremendous adaptive radiation on land (and back into water) land (and back into water) • Eucalyptus regnans (Myrtaceae) over 100m tall and 19m dbh Eucalyptus regnans (Myrtaceae) -Tasmania Angiosperms - Flowering Plants! Angiosperms - Flowering Plants! • tremendous adaptive radiation on • tremendous adaptive radiation on land (and back into water) land (and back into water) • Wolffia microscopica • Rafflesia arnoldii (Rafflesiaceae) (Araceae) less than 1mm long from New Guinea, up to 1m across and 20lbs 0.1 mm 7 Angiosperms - Flowering Plants! Angiosperms - Flowering Plants! • tremendous adaptive radiation on • tremendous adaptive radiation on land (and back into water) land (and back into water) • largest inflorescence • largest numbers of flowers — Amorphophallus titanum (Araceae) Corypha palm Angiosperms - Flowering Plants! The Flower — Why Important?! The Flower: most significant feature of angiosperms Magnoliophyta classification 1. unlike anything else in other plants & extremely variable & co-evolved with animals • previously divided into two 2. floral features used in describing and id’ing classes — dicots and monocots 3. plant specimens (herbarium) must include flowers or derived features • artificial! 4. classification of angiosperms relies on flowers • we will use Angiosperm Calochortus - fairy lanterns & mariposas (images: T. Givnish) Phylogeny Group (APG III) classification system of 2009 8 The Flower — What is it?! The Flower — What is it?! • “foliar theory” of flower - J.W. • specialized shoot = stem + von Goethe in “Attempt to Interpret leaves (folia) the Metamorphosis of Plants” (1790) • shoot is highly modified and determinate (ceased to grow) from Schleiden 1855 The Flower — What is it?! The Flower — What is it?! • developmental/evolutionary origin of the • thus, a flower is a specialized shoot that: flower still debated 1. is determinate (vs. indeterminate) 1. Euanthial theory - (foliar theory) - single shoot 2. has a modified stem with anthers compressed internodes ovules 3. possesses modified leaves with 2. Pseudanthial theory - various functions, these determined compound shoot or cone by gene arrays (e.g., ABC model) 9 The Flower — What is it?! The Flower — What is it?! The ‘ABC’ model of The ‘ABC’ model of floral part identity floral part identity The Plant Cell, 2010 B A C sepals petals stamens carpels The Flower — What is it?! The Flower! • thus, a flower is a specialized shoot that: read chpt 9 in Plant Systematics! • 1st half deals with 1. is determinate (vs. indeterminate) vegetative features - we will cover in lab 2 next week 2. has a modified stem with • 2nd half deals with flowers/ compressed internodes fruits - lab 3 following week 3. possesses modified leaves with various functions, these determined by gene arrays (e.g., ABC model) 4. often clustered in an inflorescence (larger branch) 10 The Flower! The Flower! 1. Peduncle: floral stalk, the stem 2. Receptacle: modified floral stem or supporting the flower; sometimes axis from which arise the floral referred to as the pedicel appendages or modified leaves The Flower! The Flower! 4. Petal: the second whorl of 3. Sepal: the outer whorl of leaves, leaves, typically brightly green and protective; collectively colored, attracting pollinators; called the calyx collectively called the corolla 11 The Flower! The Flower! 5. Perianth: collective term for Tepals if both similar or if only 8. Stamen: the male structure of collectively, stamens are the sepals and petals one reduced set (sepals) flower comprising filament and androecium (= ‘house of anther males’) The Flower! The Flower! 6. Filament: slender stalk of the stamen supporting 7. Anther: fertile portion of stamen that the anther; permits exsertion of anther with pollen dehisces to release pollen grains; composed of out of flower anther sacs 12 The Flower! The Flower! Nuphar Nectaries often near base of stamens - produce nectar reward for visitors • stamens can be leaf-like in primitive angiosperms! who will move pollen (‘pollinators’) The Flower! The Flower! 13. Pistil: flask-shaped, female • all pistils (1 or more) are 13. Pistil: flask-shaped, female 12. Stigma: receptive portion structure comprising three referred to as the gynoecium structure comprising three at top of style that receives main parts – often referred to (= ‘house of females’) main parts – often referred to and recognizes pollen as carpel(s) as carpel(s) 13 The Flower! The Flower! 13. Pistil: flask-shaped, female 11. Style: slender stalk of pistil 13. Pistil: flask-shaped, female 9. Ovary: basal portion of pistil structure comprising three above ovary that the pollen tubes structure comprising three that contains ovules; at maturity main parts – often referred to must pass through to reach eggs main parts – often referred to becomes fruit with seeds as carpel(s) in ovules as carpel(s) The Flower! The Flower! Pollination biology Study of the pollen, its transfer, and movement down the style 13. Pistil: flask-shaped, female 10. Ovules: fertile portions of pistil structure comprising three that contain a female gametophyte main parts – often referred to (embryo sac); develop into seeds as carpel(s) after fertilization 14 The Flower! The Flower! Monocarpic Pistil vs.