Chapter 29 Bio 221 Plant Diversity

Land Plants (+,-)

(+): Ample, unfiltered sunlight, abundant Co2, Abundant soil nutrients, Initially no natural enemies(herbivores) -(-) dessication: medium of air, not water, Access to water and nutrients(against gravity), reproductive strategies(must learn how to encorporate air), no physical support of water Ex) The motile sperm of Charophyta, the bryophytes, and Monilophytes need a water medium to find ova

Gymnosperms

(naked) and sperm, seed) -"naked seed" plants because their seeds are not enclosed in chambers EX) conifers= bear cones

Angiosperms

-(container) -consist of all flowering plants -their seeds develop inside chambers that originate within flowers -90% of living plant species are angiosperms

Foot

-Embedded in the archegonium, the FOOT absorbs nutrients from the gametophyte

Strobili

-In many Lycophytes and most gymnosperms, groups of sporophylls form cone-like structures called..

Sporocytes

-Spore mother cells that undergo meosis and produce haploid cells(spores) -are inside the sporangium

Tracheophytes

-all descendants with vascular tissue

What is the dominant stage of the life cycle for Bryophytes?

-haploid gametophytes; usually larger & longer-living than the sporophytes

Structure of flagellated sperm

-structure of the sperm closely resembles that of charophyte sperm

Seta

-the stalk of the sporophyte, conducts nutrients to the sporangium

What is a life history?

- "The changes that affect an organism's schedule of reproduction and survival."

Changes in life history for land plants:

- generations are heteromorphic (gametophyte; sporophyte) - Shift of dominance from gametophyte (n) to sporophyte (2n) -Replacement of flagellated sperm by pollen (why?) -Emergence of vascular tissue -Emergence of seeds - Emergence of flowering plants

Sporopollenin

-A layer of a durable polymer that prevents exposed zygotes from drying out -This adaptation probably allowed for charophyte descendants to live permanently above the waterline -This ability allowed for a terrestrial habitat with enormous benefits -makes the cell walls of plant spores tough and resistant to harsh environments

Mosses

-Best known of Bryophytes -Phylum: Bryophyta is a name referring to mosses -Small individual plants in tight packages that form spongy, supporting mats -anchor to substrate with rhizoids

Flowers

-Complex structure containing seeds within protective ovary. All descendants known as "Angiosperms"

Monilophytes

-Don't have seeds; use spores

Gametophore

-Each of these bud-like growths has an apical meristem that generates a gamete-producing structure known as a.. -a protonema produces these bud-like growths -bearer of the sex organs (gametangia), the female archegonia and the male antheridia.

Rhizoids

-Gametophytes are anchored by these -are long, tubular singular cells( in liverworts and hornworts) or filaments of cells( in mosses) -not composed of tissues

Leaves

-Help increase the surface area of the plant body and serve as the primary photosynthetic organ of vascular plants -Can be classified as either MICROPHYLLS: small often spine-shaped, supported by a single strand of vascular tissue or MEGAPHYLLS: leaves with a highly branched vascular system

Embryophytes

-Land plants are known as this because the multicellular dependent embryo Bryophytes-Angiosperms

Clades of Seedless Vascular plants:

-Lycophytes:club mosses and their relatives -Monilophytes: ferns and their relatives -plants with xylem and phloem

Sporophylls

-Modified leaves that bear sporangia -EX) Fern sporophylls produce clusters of sporangia known as SORI, usually on the underside of the sporophylls

Roots

-Organs that absorb water and nutrients from the soil; they also anchor vascular plants, hence allowing the shoot system to grow taller

Hornworts

-Phylum: Anthocerophyta -Resembles liverworts -name derives from sporophytes in horn-like capsules of matlike gametophyte -Cells have a single large chloroplast

Liverworts

-Phylum: Hepatophyta(liver plant) -lobed bodies hugging ground -Thalloid and leafy form -likely sister group of remaining (all other) Plantae

Lycophyta

-Plants that grow on something else; Lycopods, Club mosses, quillworts, and ground pines

Gametangia/s

-Produce gametes within multicellular organs on certain plants such as bryophytes and ferns -Female gametangia: Archegonia (pear shaped) produce nonmotile eggs; eggs are fertilized here -Male gametangia: Antheridia- produce sperm and release them into the environment

Stomata

-Support photosynthesis by allowing exchange of Co2 and O2 between the outside air and plant -Main avenue by which water evaporates from the plant

Lignin

-The water conducting cells in vascular plants are "lignified"; that is, their cell walls are strengthened by the polymer... -helped enable vascular plants to grow tall

Water plants (+,-)

-Water plants(+) Plenty of water available, doesn't fight gravity as much, water insulating, Co2 is not very limited - (-) nutrient fluctuations, light availability varies greatly, competition, lots of herbivores

Rings of cellulose-Synthesizing proteins

-circular rings of proteins in the plasma membrane -These protein rings synthesize cellulose microfibrils of the cell wall -In contrast noncharophyte algae have linear sets of proteins that synthesize cellulose

grades

-collections of organisms that share key biological features -do not necessarily share the same ancestry

Bryophyte Sporophytes morphology:

-consists of a foot, a seta, and a sporangium(Capsule)

Cuticle

-consists of wax and other ploymers -acts as waterproofing(helping prevent excess water loss from the aboveground plant organs) and protection from microbial attack

seed

-embryo packaged with a supply of nutrients inside a protective coat -Seed plants are divided into two groups: Gymnosperms and Angiosperms -All descendants known as "Spermatophytes"(gymnosperms & angiosperms)

Vascular tissue

-extensive system of cells joined in tubes that transport water and nutrients throughout the plant body upwards (Xylem) and carbohydrates downward from the leaves (Phloem) -All descendants are known as Tracheophytes(Lycophytes-Angiosperms)

Evidence that Charophytes are the closest algal relatives of plants:

-homologous chloroplasts to Kingdom Plantae; similar in structure and appearance -Biochemical Similarity: cellulose in cell wall -Similarity in mitosis, cytokinesis -Phragmoplast: Charophytes & Plants -Similarity in sperm structure -Genetic relationship: similar dna in nucleus and some ribosomal RNA is similar

Formation of a phragmoplast

-phragmoplast forms between daughter nuclei of a dividing cell; a cell plate then develops in the middle of the phragmoplast, across the midline of the dividing cell. -The cell plate in turn gives rise to a new cross wall that seperates the daughter cells -Occurs only in land plants and certain charophytes including the genera "Chara" and "Coleochaete"; they are the closing living relatives to land plants

Protonema

-produced by germinating spores from Bryophytes -is a mass of green, branched, one cell thick filaments -Large surface area that enhances absorption of water and minerals -in favorable conditions a protonema produce one or more "buds"

Sporangium

-produces spores that grow into gametophytes(2n)

Apical Meristems

-promote root and shoot growth(leaf growth), increasing exposure to environmental resources

Homosporous

-seedless vascular plants that have one type of sporangium that produces one type of spore, which typically develops into a bisexual gametophyte, as in most ferns.

The three Phyla of Bryophytes:

-small herbaceous (nonwoody) plants: -Liverworts( phylum Hepatophyta) -Mosses( Phylum Bryophyta)• Anchor to substrate with rhizoids -Hornworts( phylum Anthocerophyta) -wort= "herb" -earliest lineages to diverge from the common ancestor of land plants

Heterosporous

-species that have two types of sporangia and produces two kinds of spores: MEGASPORES which develop into female gametophytes; and MICROSPORES, which develop into male gametophytes -All seed plants and a few seedless plants are heterosporous

Capsule

-uses nutrients to produce spores by meiosis -Upper part of the capsule features a ring of interlocking, tooth-like structures known as, PERISTOME -these teeth-like structures open under dry conditions and close again when it is moist -Allows moss spores to be discharged gradually, via periodic gusts of wind that can carry them long distances

Five traits that are found in Land plants but not Charophytes(derived traits):

Alternation of Generations, multicellular dependent embryos, walled spores produced in sporangia, multicellular gametangia, and Apical Meristems

Major events in Plant evolution

Changes in life history(Alternation of Generations),Vascular tissue, seeds, flowering plants

Land Plants evolved from..

Charophytes (green algae)

Three major groups of nonvascular plants

Mosses, Liverworts, and Hornworts

What types of plants were the first to grow tall?

Phylum: Pterophyta -Ferna and other seedless vascular plants -Earliest vascular plants date to 425 mya -These plants lacked seeds but had well developed vascular systems

When did plants colonize land and when did they begin to grow taller?

Plants colonized 475mya (Ordivician) -Plants began growing taller 370mya (Devonian/Caroniferous)

Charophytes share distinctive traits with land plants:

Rings of cellulose-synthesizing proteins, Structure of flagellated sperm, and Formation of a phragmoplast

The sporophyte has multicellular organs called..

Sporangia

The two clades of living seedless vascular plants:

The Lycophytes(Phylum Lycophyta) and Monilophytes (Phylum Monilophyta) -Lycophytes include the club mosses, spike mosses, and the quillworts -Monilophytes include ferns, horsetails, and the whisk ferns and their relatives

Alternation of Generations

The sporophyte produces haploid spores by meosis, then these spores germinate and produce a Gametophyte; This Gametophyte produces haploid gametes(Sperm and Eggs) that then go through fertilization, producing a diploid zygote that develops into a multicellular diploid Sporophyte

Key adaptations of land plants

Waxy cuticle, multicellular embryo, leaves(stomata; where oxygen is released and Co2 is taken in: photosynthesis), roots, and stems. -Multicellular gamentangia, houses for the gametes

Vascular plants have two types of tissue:

Xylem: conducts most of the water and minerals from roots upwards.. It includes TRACHEIDS, tube shaped cells that carry water and minerals up from the roots. -Phloem: cells arranged into tubes that distribute sugars, amino acids, and other organic products from photosynthetic parts downards

Bryophytes

nonvascular plants (mosses, liverworts, Hornworts) -not monophyletic -growth is limited due to absence of vascular tissue and their body parts are too thin to support a tall plant -Seperate male and female gametophytes(Antheridium, male; Archegonium, female) Nonvascular, therefore only found in moist environments -Need water for sperm transport and absorption -Gametophyte generation dominates