PLANT DIVISIONS

Invasion of land• Stomata• Cuticle• Lignin: bonds to cell wall

cellulose to add strength and waterproofing

• Vascular tissue: xylem and phloem

• Roots: absorb nutrients and water vs. rhizoids of moss and holdfasts of algae that don’t.

• Seeds: dormancy• Fruit: spreading seeds• Flowers: cross pollination

Cuticle– A waxy cuticle covers parts exposed to air to prevent

dessication. Openings in the cuticle (stomata) allow for gas exchange and are controlled by the guard cells.

Guard cells

Vascular tissue– Most division (all

except bryophytes) have vascular tissue of xylem (water and minerals) and phloem (nutrients).

– Picture shows vascular tissue in a leaf in a bundle known as a vein. These are the lines you can see in the leaf.

Carbon dioxide• Plants lowered the levels of carbon dioxide from 25X

current levels to current levels over a period of 100 million years as they adapted to and spread on land.

Cuticle, Dermal tissue, ground tissue, and vascular tissue

Flagellated sperm vs. pollen• The more primitive plants have flagellated sperm

that allow them to swim to the egg. This means that the mosses, ferns, and other primitive plants require water to have fertilization.

Fern sperm

Types of pollen

Plant Divisions

• Divisions is used instead of phyla

Evolution of plants from green algae

• A certain group of green algae known as the charophytes have the following in common with plants.– Chloroplasts of both have thylakoids stacked as grana and

chlorophyll b and carotene to act as accessory pigments for chlorophyll a.

– The % of cellulose in both is around 25%– Similar mitosis and cytokinesis mechanisms– Similar sperm structure for sperm– DNA evidence backs this up.– Body of some charophytes is haploid, but fertilized egg is

retained in the organism and grows and then does meiosis: clue to how alternation of generations started.

Plants• NOTE: We use the

term Divisions instead of the term Phyla when referring to plants.

• Characteristics of plant kingdom members– Alternation of

generations with the diploid sporophyte generation dominant except in bryophytes

Plant Divisions: Bryophyta• MOSSES• Dominant gametophtye

generation (green)• Also includes liverworts and

hornworts• Need sperm to fertilize egg• NO vascular tissue limits

height of the plant and therefore have no true roots, stems, or leaves.

• haploid spores are made by meiosis in the sporangium of the sporophyte.

Moss sporophyte

Other Bryophytes

Liverworts

Hornwort

• Homospory: one type of spore

• Heterospory: female and male spore.

Gametophytes

• Antheridium Archegonium• Male gametophyte Female gametophyte• Makes sperm makes egg

Pterophyta: Ferns

• Homosporous: create one spore that is bisexual.

• Vascular tissue but no seeds: allows them to get taller, but limits them to shady moist areas for reproduction.

• Fronds: big “leaf like” arrangement• Fiddlehead: emerging sporophyte• Sporangium make spores on underside of

fronds when reproducing.

Ferns• Fiddlehead• Sporangia on

underside of frond

• Fronds• Bisexual

gametophyte

Gymnosperms (naked seeds) have no flowers: gingko, cycad, and conifers

Coniferophyta

• Redwoods, firs, pines, yews, cypresses• Naked seeds: not enclosed in fruits • Wind pollination (NEEDS A LOT)• Seeds, vascular tissue• No flowers• Often needles thick with cuticle and small

in size to limit transpiration.

Seed cones vs. pollen cones

Seed cones

seeds

Pollen cones

Oldest and largest• Redwoods (400 feet tall) bristlecone pine (4600 years old)

Anthophyta• Flowering plants• Flower will develop into fruit that is used for

seed dispersal via wind, water, or animal.• Pollination can be by wind, bird, bat, insect.• Most advanced (recent)• Gametophyte is reduced and within the

flower.• Most diverse: grasses to trees

Monocot (one cotyledon) vs. Dicot (two cotyledons): the subdivisions

of anthophyta/angiosperms

Monocots

•Often grasses and the relatives of grasses

Dicots

• Trees, garden plants

Vascular bundles locationMonocot: scattered

Dicot: ring around the outside

#2: veination in the leaves

• Parallel veins Netlike veins• Monocot Dicot

#3: number of seed parts

#4:Flower parts

• Monocot Dicot• Petals: in multiples of 3 Petals: 4 or

5

Review Questions

• Which is haploid, spore or gamete?• Which is made by mitosis, spore or gamete?• Where is the vascular tissue of a monocot?• Are ferns homosporous or heterosporous?• Do bryophytes have roots?• Do ferns have pollen?• Do gymnosperms have seeds?• Where are fern sporangia found?

Flower structure: reproduction organ of some plants

Parts: functions• Female (carpel/pistil)

– Stigma is sticky “top” that collects pollen– Style is connection between stigma and ovary.– Ovary is where eggs are made in the ovules

• Male (stamen)– Anther makes the pollen– Filament holds anther away from female part to allow for

wind/insect to carry pollen away• Petals (collectively called corona): attracts

pollinators• Sepals (collectively called calyx); protects the bud

before blooming

Monoecious (one house) plant: has both male and female on one plant

• Name the parts• Dioecious: Two

houses/ male and female plant

• Complete: one flower had both female and male while incomplete has only one

Prefixes for plants

• Mega and Arche are female• Micro and Anther are male• Microgametophyte = pollen (becomes sperm)• Megagametophyte = makes eggs• Atheridium: anthers make male gametes• Archegonium: place where eggs are made

Double Fertilization• Generative nucleus becomes two “sperm” through

mitosis. First sperm fertilizes egg in the ovule and second sperm fertilizes polar nuclei to become triploid endosperm. Endosperm will become “food” for seed.

Seed and Fruit• Seed, Develops from the ovules within the

ovaries: Covering (seed coat), food (endosperm), embryo– Allows for dormancy until conditions are right– Germination triggers massive cell division and

cellular respiration• Fruit: The ripened ovary becomes the fruit

after fertilization leading to making of the seeds: seed dispersal is the goal

• Vegetable: part of a plant you eat: not a biological term

Fruit: Seed dispersal

Review

• The helicopters of a maple tree are what part of the plant?

• What is made by the archegonium?• What part of the flower “catches the pollen?• What is one gymnosperm other than

coniferophyta?• What part of a flower becomes the fruit?• What part of the flower becomes the seed?• What are the two products of double fertilization?

More review• How do pine trees get pollen to the female?• How do apple trees get pollen to the female?• What division of plants includes the tallest trees?• What is the food of a seed called?• What is the purpose of the endosperm?• What group of green algae are the closest relatives to

plants?• What does the cuticle prevent?• What division of plant has no flowers, but does have

seeds?• What is true of plants that are heterosporous?