Plant Classification Life Cycles Alternation of generations Sporophyte

Plant Classification & Life Cycles

Alternation of generations • Sporophyte (diploid) – Begins when sperm fertilizes egg (zygote) – Diploid zygote divides by mitosis to create a mature sporophyte – Meiosis produces haploid cells called spores – Haploid spores released

Alternation of generations • Gametophyte (haploid) – Begins with spores created by meiosis – Spore grows into gametophyte • Male gametophyte creates sperms • Female gametophyte creates eggs – Sperm & egg create diploid zygote (process repeats)

Group 1: Seedless, Nonvascular Plants • Live in moist environments • Liverworts • Hornworts • Mosses

Mosses • Lack true leaves – Leaf-like structures only 1 cell thick • Rhizoids anchor into soil • Early inhabitant of new ecosystems (succession)

• Gametophyte phase – Dominant stage – Carpet of moss growing near ground Moss Life Cycle • Archegonium: produces female egg • Antheridium: produces male sperm – Sperm swims through water to fertilize egg • Sporophyte phase – Stalk grows up from the gametophyte – Sporangia houses haploid spores – Spores land new gametophyte grows See appendix B in your text book

1) Moss gametophytes grow near the ground (haploid stage) 2) Through water, sperm from the male gametophyte will swim to the female gametophyte to create a diploid zygote 3) Diploid sporophyte will grow from the gametophyte where the zygote is located . . . sporophyte gametophyte 4) Sporophyte will create and release haploid spores

5) Spores land grow into new gametophytes 6) The process repeats gametophyte ground

Plant Life Cycle Comparisons Plant type Sporophyte Gametophyte Dominant? Moss Stalk with cup (capsule) at tip, which is where spores are produced. More familiar, GAMETOPHYTE carpet-like plant that produces specialized gametes Fern More familiar, leafy plant with clusters of spore producing sacs (sori) Haploid plant body SPOROPHYTE (prothallus) is size of a finger nail, produces both male and female parts Conifer More familiar- like pine trees, produces male and female cones that produce spores Pollen grains are male gametophytes sperm, female gameotphytes are microscopic eggs SPOROPHYTE

Group 2: Seedless, Vascular Plants • Vascular system allows nutrient transport to greater heights • Club mosses • Horsetails • Ferns

Ferns • Seedless, vascular plants – Vascular: allows taller growth • Rhizoids: underground stems draw nutrients • Fronds: leaves uncurl – sporangia on underside • Sori: clusters of sporangia

Fern Life Cycle • Sporophyte phase – Dominant stage – Sporangia produces haploid spores – Spores released into air • Gametophyte phase – Spore grows into prothallus • Archegonium: produces female egg • Antheridium: produces male sperm – Sperm swims to egg – Zygote begins sporophyte stage See appendix B in your text book

1) Sporophyte creates and releases haploid spores . . Adult Sporophyte (diploid) ground

2) Spores land in the soil ground

3) From the haploid spores, a prothallus (haploid gametophyte) grows in the soil -- Rhizoids anchor Let’s zoom in ground

4) Sperm swim through water from the antheridium to the archegonia Let’s zoom back out

5) Diploid sporophyte (fiddlehead) grows from the prothallus -- prothallus eventually dies ground

6) Fiddlehead uncurls into fronds of ferns. 7) Cycle repeats -- Sporangia creates spores to be released . . . ground .

Plant Life Cycle Comparisons Plant type Sporophyte Gametophyte Dominant? Moss Stalk with cup (capsule) at tip, which is where spores are produced. More familiar, GAMETOPHYTE carpet-like plant that produces specialized gametes Fern More familiar, leafy plant with clusters of spore producing sacs (sori) Haploid plant body SPOROPHYTE (prothallus) is size of a finger nail, produces both male and female parts Conifer More familiar- like pine trees, produces male and female cones that produce spores Pollen grains are male gametophytes sperm, female gameotphytes are microscopic eggs SPOROPHYTE

Group 3: Seed producing, Vascular Plants • Type 1: Gymnosperms – Cycads – Ginko – Conifers • Type 2: Angiosperms – Anything that flowers

Group 3: Seed producing, Vascular Plants • 1) Seed plants don’t depend on water to reproduce – Pollen (contains sperm) combines with egg – Egg hardens into a seed • 2) Nourishment and protection – Nourish: Nutrients inside seed for the embryo – Protection: Hard shell • 3) Allow dispersal – Carried by wind, water, animals

Group 3: Seed producing, Vascular Plants • Type 1: Gymnosperms • Seeds not enclosed in a fruit – produced inside cones • Cone = reproductive structure • Male cones: produce pollen • Female cones: produce eggs and seeds

Group 3: Seed producing, Vascular Plants • Gymnosperm example: Conifers – Cone plants – Needle-like leaves – Common to lumber industry – Evergreen, Pine, Redwood, Cedar

Conifers • Seed advantages – Don’t depend on water – Protects & nourishes embryo – Allow plants to grow in new locations • Conifers: woody cone houses seeds – Male cones: produce pollen – Female cones: produce egg • Pines, redwoods, spruce, cedar

• The sporophyte is the dominant phase for seed plants.

1) Male and female seed cones grow in adult sporophytes

2) Pollen grains released from the male seed cones -- Pollen is the male gametophyte Let’s zoom into the female seed cone

3) Pollen grain sticks to the female ovule 4) Pollen tube grows from the male spore 5) Two nuclei transfer into female spore - one fertilizes the egg 6) Diploid embryo develops (sporophyte stage restarts)

7) After seeds harden, the cone reopens and the seeds are released

8) Seed will land ground

9) Seedling grows into (sporophyte)…the cycle repeats ground

Plant Life Cycle Comparisons Plant type Sporophyte Gametophyte Dominant? Moss Stalk with cup (capsule) at tip, which is where spores are produced. More familiar, GAMETOPHYTE carpet-like plant that produces specialized gametes Fern More familiar, leafy plant with clusters of spore producing sacs (sori) Haploid plant body SPOROPHYTE (prothallus) is size of a finger nail, produces both male and female parts Conifer More familiar- like pine trees, produces male and female cones that produce spores Pollen grains are male gametophytes sperm, female gameotphytes are microscopic eggs SPOROPHYTE

Angiosperm Life Cycle

Flowering plants are pollinated when pollen grains land on stigma • Wind pollinated flowers- small flowers and large amounts of pollen. • Animal pollinated flowers- larger flowers and less pollen (more efficient).

Fertilization takes place within the flower. Male gametophytes, or pollen grains, are produced in the anthers. – male spores produced in anthers by meiosis – each spore divides by mitosis to form two pollen grain haploid cells= pollen grain stamen anther

One female gametophyte can form in each ovule of a flower’s ovary. o Many cells can be made in the ovule • one cell becomes the egg • one cell becomes 2 polar nuclei the rest die Polar nuclei (2 n)

1. Pollen stick to animal or released into wind

• Animal finds a new flower to feed on

2. Pollen transferred to the stigma (pollination)

3. Pollen tube grows and 2 nuclei transfer into the ovule .

4. Flowering plants go through the process of double fertilization. female gametophyte egg Double Fertilization sperm polar nuclei ovule 1 sperm fuse with the polar nuclei = triploid (3 n) endosperm 1 sperm fuse with the egg = zygote

5. Each ovule becomes a seed. endosperm Endosperm provides food supply for embryo seed coat embryo 6. The surrounding ovary grows into a fruit.

7. Flower dries up and fruit falls to ground.

8. Animals eat fruit…. seeds come out the other end…

9. Seeds get dispersed 10. Seed germinates, (sporophyte) and the cycle starts over ground

22. 2 Flower Life Cycle Plant type Sporophyte Moss Plant Life Cycle Comparisons Gametophyte Dominant? Stalk with cup (capsule) at tip, which is where spores are produced. More familiar, carpet-like plant that produces specialized gametes GAMETOPHYTE Fern More familiar, leafy plant with clusters of spore producing sacs (sori) Haploid plant body (prothallus) SPOROPHYTE is size of a finger nail, produces both male and female parts Conifer (gymnosperm) More familiar- like pine trees, produces male and female cones that produce spores Pollen grains are male SPOROPHYTE gametophytes sperm, female gameotphytes are microscopic eggs Flower (angiosperm) More familiar- apple tree, peach tree, zucchini, berries, etc. Contain flowers that produce male and female spores Pollen grains are male gametophytes 2 haploid cells = pollen tube + sperm, Female gametophyte in ovule egg + 2 polar nuclei SPOROPHYTE

End of the Semester!