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WHEN?

TUESDAYTUESDAY Mar. 3

6:00-7:00 PM

Guest Speaker: Dr. David SteenGuest Speaker: Dr. David Steen““Road mortality and freshwater turtle Road mortality and freshwater turtle

conservation in North Americaconservation in North America””

Also: Info on Tigers 4 Tigers plans for spring semester!

WHERE? 112 Rouse

Life Sciences

Ch. 7: Plant Growth and Reproduction

Plant Growth• Includes:

– phenology– location of overwintering buds (criterion for

major subdivisions)

Fig. 7.2

Plant Growth• Main Raunkiaer categories (7):

– 7) Epiphyte: germinates & grows on plants

Lab #3: Who am I??

Epiphyte Focus• Effect on host:– Negligible (commensalism: one benefits & other

unaffected) – (+,0) (epiphyte, host)

Epiphyte Focus• Effect on host:

– Positive. Canopy roots (host): roots

– Mutualism: (+,+)

Trees knownto form canopyroots

Parasitic Epiphytes• Negative: Parasites. Tap • Parasitism. (+,-) (epiphyte, host)

Parasitic Epiphytes• Holoparasites: No chlorophyll. Haustoria (modified

roots) penetrate • Ex, dodder (Cuscuta)

“Witches hair”“Love vine”

Parasitic Epiphytes• Hemiparasites: Chlorophyll-- water & nutrients from

• Ex, Who am I? (Lab #3)

Plant Reproduction

• 2 main types

Two main types…..

Plant Reproduction• Sexual reproduction: genetically varying

offspring (via meiosis & fertilization)

Plant Reproduction• Asexual reproduction: genetically identical

offspring (involves mitosis)– Ex, clonal growth (discussed)

Plant Reproduction• Agamospermy: seeds asexual (CLONES)

– Exs: Taraxacum (dandelion), some Rubus

Plant Reproduction• Asexual reproduction: genetically identical

offspring• Sexual reproduction: genetically varying

offspring (via meiosis and fertilization)

Plant Reproduction• Meiosis: reduction

division• 2N to 1N

Plant Reproduction• Fertilization: gametes (egg+sperm) form

• 1N to 2N

Human example….

Plant Life Cycle• Life cycle: Involves 1) meiosis, 2) fertilization, 3)

haploid cells, 4) diploid cells

Plant Life Cycle• Sporic meiosis:• 2 bodies, 1 cycle: alternation of generations• Sporophyte 2N, gametophyte 1N

Plant Life Cycle• Gametophyte (1N): gametes BY MITOSIS• Fertilization: zygote (2N)

Start

Plant Life Cycle• Zygote to sporophyte (2N): mitosis• Sporophyte: spores BY MEIOSIS• Spore to gametophyte:

End

Plant Life Cycle• Mosses: gametophyte leafy

– Sporophyte on

Granite outcrop lab

Plant Life CycleSeed plants + ferns: major body = _______

Who am I? (Lab 3)Epiphyte fernSite for sori….

Lab #1?

Where other “body”?

Plant Life Cycle• Where

gametophytes?– Seed plants:

male = pollen grain

Ferns

Plant Life Cycle• Female

gametophyte (embryo sac): inside ovule

Ovules in ovary

Life Cycle• Mature male gametophyte =

• Fertilization: sperm & egg form zygote (2N)

DOUBLE fertilization!

Life Cycle• Zygote: embryo in ovule• Endosperm: nutritive

• Ovule into seedWhat’s a seed??

Life Cycle• Seed: baby plant ( : new sporophyte) in

box ( coat) with lunch ( : flowering plants)

Terms• Flower parts (BIOL 1030)• 4: sepals, petals, stamens, pistil(s)

Carpel=Pistil here

Floral variation• Fusing petals

– Long-tongued/long-billed pollinators

Who am I? (Lab #3)seeds

Floral variation• Stamens & pistils: perfect flowers

Floral variation• Some imperfect. • Pistillate (pistil) or staminate (stamens)

Staminate flowers of SagittariaPistillate flowers of Sagittaria

Floral variation• Pistillate & carpellate .: dioecious (MUST

outcross)• Monoecious: both sexes

Cones!

Floral variation• Ex. dioecious species: Persimmon

(Diospyros virginiana)

Persimmon fruits

Staminateflower

Pistillateflower

Floral variation• Complete flowers: all 4 parts (sepals, petals, stamens,

pistil)• Lack : incomplete flowers

Diospyros?

Floral variation• Group flowers: inflorescence

– One type: head– Ex, sunflower (Asteraceae)– Ray flowers: lg. – Disk flowers sm.

diskflowers

ray flowers

Floral variation• Who am I? (Lab #1)

– Inflorescence: white structures = bracts

Inflorescence Closeup showing individualgreenish flowers

Pollination• Why flowers vary? Many form mutualism w/ animals

Terms• Pollination (flowering plants): transfer

Carpel=pistil

Terms• Fertilization: sperm fuses w/ egg (in ovule),

makes

Pollination• Abiotic: pollen carried

Wind Pollination• Grasses, temperate trees

(Quercus, Carya, Pinus)• Not

CaryaA grass

Terms• Biotic pollination: pollen carried by animal--

90% flowering plants– Floral visitor: visits – Pollinator: deposits

Pollination as MutualismMutualism (+,+) interaction

– Plant gets– Animal gets

Reward?

Animal Rewards• Pollen: hi • Also lipids,

Renewable…