PLANTS!! Food, habitats, carbon dioxide taker uppers, oxygen providers What more could we ask for???

PLANTS!!Food, habitats, carbon dioxide taker uppers, oxygen providers

What more could we ask for???

Kingdom: Plantae• 280,000 species

• Ecological, industrial and medical importance

• Thought to evolve from green algae, 500 mya• Both have chlorophyll a and b, store excess carbs, cellulose in cell

walls.

4 Evolutionary milestones

• Nonvascular plants that nourish a multicellular embryo within the body of the female plant (different from green algae)• Vascular tissue specialized for transport (430

mya)• Production of seeds (contains embryo and

stored nutrients within a protective coat) 400mya• Flower –reproductive structure 135 mya• See cladogram pg 415

Alternation of Generations• 2 multicellular individuals alternate, each produce the other

1. Sporophyte – diploid generation2. Gametophyte – haploid generation

Sporophyte generation (2n)• Sporophyte – production of spores by meiosis• Spore – haploid reproduction cell that develops a new organism

without fusing with another organism.• Spores undergo mitosis and becomes a gametophyte

Gametophyte generation (n)• Production of gametes• Sperm and eggs are developed by mitosis• fuse = diploid zygote• Undergoes mitosis = sporophyte

Alternation of generations• Meiosis produces haploid spores (gametophyte generation)• Mitoisis occurs when• Spore becomes a gametophyte • Zygote becomes a sporophyte

Alternation of Generations• In nonvascular plants – gametophyte is dominant • Vascular seedless, naked seed and flowering plants –

sporophyte is dominant• Adaptation to life on land• Gameotphyte becomes microscopic

Adaptations to terrestrial life• Water transport and conservation – vascular tissue• Protection from desiccation – waxy cuticle, stomata

Nonvascular Plants

• No means of transporting water or organic nutrients• No true roots, stems or leaves, just root like…• bryophyte – term for nonvascular plants• Gametophyte is dominant generation, the part

of the plant we see.• Females produce eggs in archegonia• Males produce flagellated sperm in antheridia• need film of water for sperm to meet egg

• Characteristics limits size of bryophytes• 3 phyla, hornworts, liverworts, and mosses

Hornworts and liverworts• Hornworts – most live in moist shaded areas• Can reproduce asexually by fragmentation• Horns are sporophyte that grow from gametophyte

• Liveworts – most terrestrial, some epiphytes• Thallose – with a flattened thallus• Leafy – look like mosses• Lobes look like liver• Phizoids – extensions that anchor in soil

Mosses

• Gametophyte appear as leaflike structures • Peat, true and rock mosses• Prefer damp, shaded areas, can dry up and turn

brown, and be revived with rain• Can reproduce asexually by fragmentation• Moss life cycle figure 24.9• Uses include • sphagnum – ability to absorb water, used in gardening• Peat – accumulated dead moss can be used as fuel

and bandages.

Vascular plants• Xylem – conducts water and minerals up from the roots• Walls of cells are strengthened by lignin

• Phloem – conducts sucrose and other organic compounds down from point of photosynthesis

• Seedless vascular – homosporous (1 type)• Seed plants – heterosporous (2 types, m/f), leads to evolution

of pollen grain and seed

Seedless vascular plants• Sporophyte dominant• Independent gametophyte, archegonium and antheridium,

still need water.• Club mosses • Ground pines, spike mosses and quillworts• Have 1 strand of vascular tissue• Rhizome – horizontal underground stem• Strobili (cones) – contain sporangia

Seedless vascularFerns and allies• Horsetails• Have rhizomes and stroboli

• Whisk ferns • No leaves, sporangia are yellow, look like whisk broom

• Fern• first fiddleheads that unrolls into fronds• Megaphylls (more than 1 vascular strand)• Dominant sporophyte produces windblown spores• Life cycle figure 24.16• Uses: decorative, building material, medicinal, expel

intestinal parasites

Seed plants

• Gymnosperms (naked seed) and angiosperms (flowering plants)• Contain sporophyte embryo and stored food

within a protective seed coat• Allows survival during harsh conditions

• Heterosporous, 2 types of gametophytes (m/f)• Pollen grains – male gametophyte• Pollination – when pollen grain is brought to vicinity of

female gametophyte by wind/pollinator, no water needed!• Female gametophyte develops within an ovule which

eventually becomes a seed

Gymnosperms• Conifers, cycads, ginkgoes and gnetophytes

• Ovules and seeds are exposed, not enclosed by fruit (naked seed)

Conifers• Conifers – evergreens, including pines, spruces, firs, cedars,

redwoods…bears cones• Tallest – redwood, oldest – bristlecone pine

• Life cycle of pine fig. 24.18• Used in construction, soft due to amount of xylem tissue, resin

(turpentine)• Monoecious – tree produces both pollen and seed cones

Cycads• Tropical, subtropical• Used in landscaping, resemble palms• Pollen and seed cones on separate plants• Pollinated by insects

Ginkgoes• Maidenhair tree• 1 species remains, Gingko biloba• Dioecious – some trees produce seeds, other pollen• Female seeds produce an odor, males preferred• Resistant to pollution• Seeds a delicacy• Extracts used medically

Gnetophytes• Lack archegonia, like angiosperms, thought to be most closely

related • Ephedra – shrub, ephedrine is extracted

Angiosperms• Flowering plants• Provide clothing, food, medicines • Ovules are enclosed within diploid tissues• Dominance of angiosperms is related to evolution of flying

insects (pollination)

Monocots and Eudicots• Cotyledon – seed leaf, contains nutrients that nourish the

plant embryo• Monocots – corn, tulips, poineapple, bamboo• Eudicot – cactuses, strawberries, dandelions

The Flower• Common structures in all flowers• Peduncle – flower stalk• Receptacle – expanded tip, contains the following:• Sepals – (calyx) – protect the flower bud before opening• Petals – (corolla) – differ in color, shape and size• Stamens – consists of anther (produce pollen grains) and

filament• Carpels – stigma (sticky knob), style (stalk) and ovary (enlarged

base that encloses ovule)

Flowering plant life cycle• Megaspores – in ovule within ovary of carpel, develops into

egg bearing female gametophyte embryo sac• Microspore – produced in anthers, pollen grains, develop into

sperm bearing male gametophytes

• Fruit – derived from an ovary

Diversificaiton• Wind pollinated – usually bland• Insect/bird pollinated – usually colorful• Night blooming flowers – aromatic and white

• Fruits protect and aid in dispersal of seeds