Spermatophytes Flashcards
Characteristics of Spermatophytes (Seed Plants)
- Heterosporous
- Retention of Megaspore and female gametophyte on sporophyte
- Ovule
- Pollen
- Seeds
Ovule
An integumented megasporangium bearing a single functional megaspore
- Endosporic (inside spore wall)
- Nucellus
- Integuments
- Micropyle
Nucellus
The modified, fleshy megasporangium
-Ovule
Integuments
Flaps of sporophyte tissue covering nucellus
-Ovule
Micropyle
An opening through integuments
-Ovule
Meiosis
Occurs in nucellus
- produces 1 megaspore (3 abort)
- Megaspore germinates
Female gametophyte
Several archegonia
-No neck
Seed
Mature ovule bearing an embryo
- Seed coat
- Nutritive tissue
- Embryo
Embryo
Inside of seed
- Baby sporophyte
- Cotyledons (seed leaves)
- Apical meristem
- Hypocotyle (stem)
- Radicle Root
Generations in Seeds
- Embryo
- Nutritive tissue (maternal gametophyte)
- Seed coat (maternal sporophyte)
Pollen
Endosporic Male gametophyte plant
- Prothallial cells
- Generative cell
- Tube cell-makes pollen tube
Pollen wall
Elaborately sculptured outer layer and coated w/ sporopollenin
-Pores-doors through which pollen tubes germinate
Pollen Variation
Dif size, shape, structure, sculpting
-Pollen must land on receptive surface of right species to germinate
Steps of Seed Plant Reproduction
- Pollination-Pollen born to ovule
- Pollen Germination
- Syngamy-Embryo created
Gymnosperm Characteristics
- Naked seeds
- Polyembryony
- Tracheids but no vessel elements
Polyembryony
Only 1 embryo in a seed survives out of the many formed
-Gymnosperms
Zooidogamy
“High Drive”
- Ancestral
- Pollen tube releases sperm into sperm lake
- Multiflagellate sperm swim to egg
Siphonogamy
“Conveyor Belt”
- Derived
- Pollen tube grows toward ovule
- Pierces egg and releases naked sperm into egg
Zooidogamous Gymnosperms
Ancestral
- Cycadophyta
- Ginkophyta
Siphonogamous Gymnosperms
Derived
- Coniferophyta
- Gnetophyta
Cycadophyta
Sp Div-7th Eco Div- Tropical and relictual -Leaves resemble palm trees -Circinate vernation -Coralloid roots -Strobili -Zooidogamy
Coralloid Roots
Symbiotic relationship b/w cycad root and nitrogen fixing bacteria
- Bacteria provides nitrogen
- Cycadophyta
Ginkgophyta
Sp Div-10th Only 1 species! Eco Div-Mountains of China and common landscape -Zooidogamy -Fan-like leaves -Ovules on shoots
Coniferophyta
Sp Div-6th
Eco Div-widespread, dominant in taiga/boreal forests and east TX
-Very large w/ needles
-Resin ducts
-Compound female cones with bract-scale complexes
-Siphonogamy
Resin Ducts
Cavity lined w/ secretary parenchyma
- Resin made of turpentine and Rosin (wax)
- When duct is broken turpentine evaporates and resin dries which traps pathogens and seals opening
- Coniferophyta
Strobili
Bear reproductive structures
-Microstrobili bear microsporangia and megastrobili bear ovules
Conifer Pollen
Produced in microstrobili
-Have wings so dispersed by wind
Gnetophyta
Sp Div-9th
- Have some angiosperm-like features (ovules)
- Siphonogamy
- Primative vessels (embryo sacs)
Ephedra
- Gnetophyta
- Source of ephedrine, used to treat asthma, allergies, source of meth
Megastrobili
Ovules born on scale (hard, modified branches) in axil of bracts
