plants & plant diversity

includes the evolution of plants (from aquatic to land), the different phyla of plants and their characteristics, and the subcategories of flowering plants

what’s included in Kingdom Plantae

• green algae

• land/aquatic plants

characteristics of Kingdom Plantae

• chloroplasts with chlorophyll a, b, and beta-carotene

• multiple membrane layers in chloroplasts

• cellulose wall

• starch as energy storage product

thylakoid condition

stacked and flattened vesicles without connection to the inner of the two membranes enclosing the chloroplast for more efficient extraction of radiant energy 

function of chlorophyll a, b, and beta-carotene 

allows for wider spectral sensitivity in green algae and land plants, evolved for early competition for sunlight 

function of cellulose wall

resides outside flexible cell membrane and gives greater protection and structural support

conditions leading to the evolution of Plantae

• wavelength resource limitation

• CO2 becoming less available underwater

• evidence of early competition for energy sources in the aquatic environment

• new ecological niches

photosynthesis evolved in

cyanobacteria (prokaryote) 

challenges of life on land for plants

• dehydration (getting enough water for photosynthesis)

• support of plant structure above ground (overcoming gravity)

• transportation of water from submerged cells to air-exposed cells

• transportation of photosynthate sugars to non-photosynthesizing cells i.e., root cells

• sexual reproduction (flagellated sperm can no longer swim)

• exposure to harmful UV radiation (blue end of wavelength spectrum)

cuticle

a hydrophobic waxy substance that acts as a protective outer layer to plants and prevents water loss

important evolutionary trend within the plant kingdom 

increase in the tendency for plants to be able to survive farther and farther away from water 

stroma

fluid within the thylakoid membrane

granum

stack of thylakoids (pancake structures)

pores

also known as stomata. openings within the plant that allow for CO2 to enter in.

non-vascular plants without cuticle

• purely simple aquatic plants that don’t have adaptations for living on land

• phylum: chlorophyta (green algae i.e., stonewarts charalaes)

• no specialized transport tissue is present

non-vascular plants with cuticle

• first to have stoma (pores)

• reproduce with spores and not seeds

• absorption of water via diffusion

• phylum: Bryophyta (mosses)

• first land plants!

vascular, seedless plants

• the first plants with vascular tissue/system! (phloem and xylem)

• phylum: Pteriodphyta (ferns)

• limited sexually to moist environments

• club mosses, horsetails, whisk ferns, ferns

• sporophyte is the dominant life cycle as in all higher land plants

sporophyte 

the diploid, spore-producing stage in the life cycle of plants and some algae, which alternates with the haploid gametophyte stage

vascular tissue function

enables plants to grow to taller heights since water can be transported throughout greater distances

vascular, naked-seed plants 

• gymnosperms 

• innovation of pollen (air borne sperm) 

• dehydration resistant seeds enable greater freedom and dispersal of sexual reproduction on land (these are the plants that humans have pollen allergies to) 

• 4 major divisions: cyads, ginkos, conifers, and gnetophytes (pines, spruces, firs) 

• phylum: Conierophyta 

• gametes are produced within the cones 

vascular plants with fruit-covered seeds

• angiosperms

• all of the flowering plants (largest number of species of all plants)

• fruit increases the protection and dispersal of seeds

• flowers facilitate pollination by attracting pollinators (that’s why they’re so pretty!)

• fruits are mature ripened ovaries enclosing seeds

• phylum: anthophyta

the two groups within phylum anthophyta

1) monocotleydons (monocots)

2) dicotleydons (dicots)

monocotleydons (monocots)

(subtype of angiosperm)

• one leaf at germination

• scattered vascular bundles

• parallel leaf veins

• petals in multiples of 3

ex) lillies

dicotleydons (dicots)

(subtype of angiosperm)

• two leaves at germination 

• circular vascular bundles (arranged around periphery of plant stem)

• leaf veins are branched off

• petals in multiples of 4 or 5

ex) hibiscuses

differences in amounts of cellulose in plants

• aquatic plants tend to have less cellulose

• terrestrial plants tend to have more cellulose as they require more rigidity in their cell walls to give them structural upright support

evidence of competition as a driving factor in plant evolution

• elongated cells

• contractile fibers

• cytoplasmic streaming

• cellulose