Plant Reproduction and Diversity

Know the phylogenetic relationships among the three major groups of plants presented in

class (nonvascular plants, seedless vascular plants, and seed plants)

Nonvascular Plant: mosses, liverworts, hornworts (Leave Money Hoe) - gametophyte - paraphyletic

Seedless Vascular Plant: Lycophytes, Monilophytes (live more) - sporophyte - paraphyletic

Seed Plants: gymnosperms, angiosperms (greatly alone) - sporophyte - monophyletic

Key Innovation #1: Embryo Protection

• gametophyte protects the developing sporophyte

• Land plants are all embryophytes and so its the first trait on the tree

• It increased the more land plants, CO2 uptake, long-term carbon storage, boosted O2 levels, decreased Co2, and increased transpiration/rainfall movement

Key Innovation #1: Cuticle and Stomata

Cuticle → waxy outer coating that goes over epidermis of leaves and other plant parts

Stomata → microscopic pores surrounded by guard cells in the epidermis of leaves and stems that allows for gas exchange between the environment and the interior of the plant

Cuticles → all land plants but for stomata it doesn’t include liverworts

Cuticle allows plants to not dry out and stomata controlled gas exchange (co2 coming in and o2/h2o being lost)

Vascular Tissue (Xylem and Phloem)

cells used for conducting water and minerals (xylem) and phloem (water and sugar)

• only found in vascular plants → NOT NONVASCULAR

• allowed plants to grow tall

• paved the way for stratified habitats

• changed way plants compete for light

• affected water transport rates which greatly change the carbon cycle

• increase o2 production and co2 removal

Root like structures and roots

first one were rhizosomes → shoots that help anchor plants and obtain water and nutrients from soil

• ONLY VASC PLANTS

• allows for larger and more complex body layout

• greatly enhances water and nutrient absorption

• increasing photosynthesis and growth rate

• promote soil formation and prevent erosion

Wood (secondary growth)

in other words, xylem.

• evolved independently in lyphocytes and seed plants

• allowed plants to grow even taller and grew the first forest

• more carbon but also affected the global climate

microphylls and megaphylls

• leaves are lateral appendages growing on sporophytes

• microphylls are unbranched vascular tissue

• megaphylls is branched vascular tissue

Lyophytes → microphyll leaves

Monilophytes → megaphylls

• increased photosynthesis and surface area for light capture

• stomata variability allows for more gas exchange, water loss and temperature

non free living gametophyte

• gametophyte is dependent on the sporophyte

• diverging plant lineages have more reduced gametophytes

• protected by sporophyte

• better dispersal

• less dependent on water

heterospory

homosporous plants produce only 1 type of spore which produces a bisexual gametophyte

• either male or female gametophytes

• higher megaspores and low investment microspores

• long distance travel of small microspores

• paves way for evolution of pollen and seed

pollen grain

Pollen Grain

• structure made of sporophyte tissue that contains the male gametophyte → uses sporopollelin for protection and to prevent drying out

• eliminates the need for water as part of reproduction

• can be dispersed great distances by plants or animals

• Prevents drying out of gametophytes

Ovule

• structure made of sporophyte tissue that contains the female gametophyte, and when this develops, the ovule turns into a seed

  • megasporangium → holds the big spore, which is a megaspore

Importance

• can remain dormant for years until conditions are favorable for it

• They have their supply of stored food

• may be transported long distances by winds or animals

Flowers

• specialized shoots w/ modified leaves

  • sepals

  • petals

  • stamen

  • carpels

• unique to angiosperms

Fruits

• fertilized ovary that further develops

  • often involves development of the wall

    • encloses and protect seeds

    • increased dispersal ability