TOPIC 5
PLANT DIVERSITY, FORM & FUNCTION
I. ORIGINS & INNOVATIONS OF TERRESTRIAL PLANTS
II. NONVASCULAR PLANTS
III. SEEDLESS VASCULAR PLANTS
IV. VASCULAR SEED PLANTS: GYMNOSPERMS
V. VASCULAR SEED PLANTS: ANGIOSPERMS
VI. TRANSPORT SYSTEMS IN VASCULAR PLANTS
VII. PLANTS IN ECOSYSTEMS
I. ORIGINS & INNOVATIONS
4 MAJOR SYNAPOMORPHIES
1. ALTERNATION OF GENERATIONS
[475 MILLION YEARS BP]
2. VASCULAR TISSUE
[425 MILLION YEARS BP]
3. SEEDS
[360 MILLION YEARS BP]
4. FLOWERS
[130 MILLION YEARS BP]
ORIGINS: CHAROPHYTES, CLOSEST ALGAL RELATIVES
FRESHWATER MULTICELLULAR CHLOROPHYTES (GREEN ALGAE)
SIMILARITIES WITH PLANTS
GENETIC EVIDENCE
= rRNA, nDNA, mDNA
CELL WALL
20 - 25 % CELLULOSE
DETAILS OF MITOSIS
CHLOROPLASTS
CHLOROPHYLL-b & BETA-CAROTENE
THYLAKOID MEMBRANES = GRANA
ORIGINS OFALTERNATION OF GENERATIONS
PRECURSOR IN CHARAPHYTE - COLEOCHAETE
HAPLOID PHOTOSYNTHETIC
BODY (THALLUS)
RELEASES ONLY SPERM
RETAINS EGG
EGG IS FERTILIZED & ZYGOTE RETAINED
STATIONARY ZYGOTE UNDERGOES MEIOSIS
RELEASES 4 HAPLOID SPORES = > NEW THALLUS
HYPOTHETICAL STAGE
ZYGOTE UNDERGOES MITOSIS BEFORE PRODUCING HAPOLID SPORES VIA MEIOSIS
= MULTICELLULAR DIPLOID STAGE
PROTECTED & NOURISHED BY HAPLOID STAGE
= EMBRYOPHYTE
EACH FERTILIZATION PRODUCES MORE SPORES = MORE NEW INDIVIDUALS
ADAPTIVE IF FERTILIZATION IS RARE
BENEFITS OF TERRESTRIAL COLONIZATION
HIGHER LIGHT LEVELS
MORE CARBON DIOXIDE
ABUNDANT MINERIALS IN SOILS
INITIALLY NO HERBIVORES
COSTS OF TERRESTRIAL COLONIZATION
MUCH LESS WATER AVAILABLE FOR:
PHOTOSYNTHESIS
CELLULAR REACTIONS
REPRODUCTION & DISPERSAL
SPECIALIZED STRUCTURES & CHEMICALS REQUIRED FOR:
SUPPORT
COLLECTION OF WATER & MINERALS
WATER CONSERVATION
GAMETE PRODUCTION (GAMETANGIA)
PHOTOSYNTHESIS
II. NONVASCULAR PLANTS
"BRYOPHYTES"
18,600 LIVING SPECIES
DIVISIONS
BRYOPHYTA - MOSSES
HEPATOPHYTA - LIVERWORTS
ANTHOCEROPHYTA - HORNWORTS
LACK TRUE VASCULAR TISSUES FOR INTERNAL WATER CONDUCTION
NO XYLEM
NO PHLOEM
LACK TRUE LEAVES, STEMS & ROOTS
EVOLVED FEATURES FOR WATER CONSERVATION
CUTICLE = WAXY COVERING ON LEAVES & STEMS
STOMA (STOMATA) = MICRO-PORE FOR GAS EXCHANGE
PHOTOSYNTHESIS = CARBON DIOXIDE IN OXYGEN OUT
BRYOPHYTES ARE EMBRYOPHYTES
GAMETOPHYTE (1n) GENERATION DOMINATES
MITOSIS => SPERM OR EGG
MALE GAMETANGIUM = ANTHERIDIUM
FLAGELLATED SPERM
FEMALE GAMETANGIUM = ARCHEGONIUM
1 LARGE, SEDENTARY EGG
ZYGOTE DEVELOPS WITHIN FEMALE GAMETOPHTYE
=> SPOROPHYTE (2n) GENERATION
MEIOSIS IN SPOROPHYTE => SPORES (1n)
PROTECTED BY SPOROPOLLENIN COAT
III. SEEDLESS VASCULAR PLANTS
13,000 LIVING SPECIES
DIVISIONS
LYCOPHYTA - LYCOPHYTES (CLUB MOSSES)
SPHENOPHYTA - HORSETAILS (EQUISETUM)
PTEROPHYTA - FERNS
POSSESS VASCULAR TISSUES FOR INTERNAL CONDUCTION
XYLEM & PHLOEM
XYLEM = UPWARD TRANSPORT
PHLOEM = DOWN OR UP
POSSESS LIGNIN IN CELL WALLS = PROVIDES MECHANICAL SUPPORT
REPRODUCTION IN SEEDLESS VASCULAR PLANTS
LIKE BRYOPHYTES
FERNS & RELATIVES DISPERSE VIA HAPLOID SPORES
UNLIKE BRYOPHTES
IN FERNS & RELATIVES THE SPOROPHYTE (2n) IS DOMINANT
THE GAMETOPHYE (1n) IS FREE LIVING, BUT REDUCED IN FERNS
SPOROPHYTES HAVE LARGE COMPOUND LEAVES (MEGAPHYLLS)
SPOROPHYTES PRODUCE SPORES VIA MEIOSIS IN SPORANGIA
FERNS ARE HOMOSPOROUS
SPOROPHYTE => 1 TYPE OF SPORE => BISEXUAL GAMETOPHYTE
BISEXUAL GAMETOPHYTE BEARS 2 TYPES OF GAMETANGIA
ANTHERIDIA => FLAGELLATED SPERM
ARCHEGONIA => SESSILE EGGS
SOME LYCOPHTYA (SELAGINELLA) ARE HETEROSPOROUS
SPOROPHYTE => 2 TYPES OF SPORE =>
LARGE MEGASPORE => FEMALE
GAMETOPHYTE => EGGS
SMALL MICROSPORE => MALE
GAMETOPHYTE => SPERM
MEGASPORE REMAINS ATTACHED TO PARENT SPOROPHYTE
FEMALE GAMETOPHYTE DEVELOPS WITHIN MEGASPORE WALL & EGGS ARE FERTILIZED THERE
PATTERN OF DEVELOPMENT IS ANALOGOUS TO A SEED
IV. VASCULAR PLANTS GYMNOSPERMS
GYMNOSPERMS = "NAKED SEEDS"
720 LIVING SPECIES
DIVISIONS
CONIFERPHYTA - CONIFERS (CONE BEARING)
CYCADOPHYTA - CYCADS
GINGKOPHYTA - GINKGO
GNETOPHYTA
GYMNOSPERM SEEDS ARE NAKED = OVULES ARE NOT CONTAINED IN CHAMBERS OR OVARIES
= SITE OF FERTILIZATION & SEED DEVELOPMENT
FERTILIZATION DOES NOT REQUIRE WATER
SPERM ARE PRODUCED BY RESISTANT POLLEN GRAINS
A SEED IS COMPOSED OF:
A DIPLOID EMBRYO
A STORE OF FOOD
A RESISTANT OUTER COAT
GYMNOSPERM REPRODUCTION
ILLUSTRATED BY CONIFERS
SPOROPHYTE IS DOMINANT
GAMETOPHYTE IS REDUCED & DEPENDENT
GYMNOSPERMS ARE HETEROSPOROUS
(MALE) POLLEN CONES BEAR SMALL SPOROPHYLLS
SPOROPHYLLS BEAR MICROSPORANGIA (2n)
MICROSPORANGIA PRODUCE MALE GAMETOPHYTES VIA
MEIOSIS = POLLEN GRAINS (1n)
POLLEN GRAINS PRODUCE SPERM VIA MITOSIS
(FEMALE) OVULATE CONES BEAR SCALE-LIKE SPOROPHYLLS
SPOROPHYLLS BEAR MEGASPORANGIA (NUCELLI) (2n) IN OVULES
MEGASPORANGIA PRODUCE MOTHER CELLS (2n) WHICH
BY MEIOSIS PRODUCE MEGASPORES (1n)
MEGASPORES DEVELOP INTO FEMALE GAMETOPHYTES (1n)
FEMALE GAMETOPHYTES DEVELOP ARCHEGONIA
ARCHEGONIA BEAR EGGS VIA MITOSIS
POLLINATION
POLLEN GRAIN REACHES MICROPYLE OF OVULE
FERTILIZATION
POLLEN GRAIN PRODUCES POLLEN TUBE
SPERM NUCLEUS TRAVELS THRU TUBE INJECTED BY TUBE INTO EGG
NUCLEI FUSE = ZYGOTE (2n)
SEED COMPONENTS
GYMNOSPERM SEED
ZYGOTE = > EMBYRONIC SPOROPHYTE (2n)
FOOD FOR EMBRYO = > FEMALE GAMETOPHYTE (1n)
SEED COAT = > INTEGUMENT OF PARENTAL SPOROPHYTE (2n)
ANGIOSPERM SEED
ZYGOTE = > EMBYRONIC SPOROPHYTE (2n)
FOOD FOR EMBRYO = > ENDOSPERM (3n)
SEED COAT = > INTEGUMENT OF PARENTAL SPOROPHYTE (2n)
WOOD
PLANTS DISPLAY INDETERMINATE GROWTH
ACHIEVED BY MERISTEMS
= PERMANENTLY EMBRYONIC CELLS
CONIFERS DISPLAY SECONDARY GROWTH
= INCREASE IN GIRTH AS WELL AS LENGTH
SECONDARY GROWTH DUE TO:
VASCULAR CAMBIUM
CORK CAMBIUM
ANGIOSPERMS DISPLAY SECONDARY GROWTH AS WELL
VASCULAR CAMBIUM
XYLEM ON INSIDE
PHLOEM ON OUTSIDE
MATURE XYLEM TRACHEIDS HARDENED BY LIGNIN
ALSO LIGNIFIED FIBER CELLS
PHLOEM IS INNER PART OF BARK
CORK CAMBIUM
PRODUCES OUTER CORK CELLS OF BARK
CELLS SECRETE WAXY SUBERIN = PROTECTIVE LAYER
V. VASCULAR PLANTS ANGIOSPERMS
DIVISION ANTHOPHYTA
FLOWERING PLANTS
250,000 LIVING SPECIES
2 CLASSES BASED ON # OF EMBRYONIC LEAVES
MONOCOTS
(1 COTYLEDON)DICOTS
(2 COTYLEDONS)
ALSO DIFFER IN:
LEAF VENATION
STEM STRUCTURE
ROOT ORGANIZATION
ARRANGEMENT OF FLOWER PARTS
DICOTS ARE MORE DIVERSE THAN MONOCOTS
MONOCOTS ARE VERY IMPORTANT IN FOOD PRODUCTION
ANGIOSPERMS
FLOWER STRUCTURE
4 NESTED SETS OF MODIFIED LEAVES
1. SEPALS (GREEN)
2. PETALS (COLORED)
3. STAMEN
FILAMENT (STALK)
ANTHER (CONTAIN SPORANGIA
= POLLEN SACS)
4. CARPEL
STIGMA (POLLEN COLLECTOR)
STYLE (NECK)
OVARY
1 OR MORE OVULES (CONTAIN SPORANGIUM)
ANGIOSPERMS
TYPES OF FLOWERS
COMPLETE FLOWER = ALL 4 FLORAL ORGANS
vs.
INCOMPLETE FLOWER = LACKS 1 OR MORE FLORAL ORGANS
PERFECT FLOWER = BOTH STAMENS & CARPELS (BISEXUAL)
vs.
IMPERFECT FLOWER = LACKS 1 OR THESE STRUCTURES (UNISEXUAL)
IF FLOWERS ARE IMPERFECT:
MONOECIOUS = LOCATED ON SAME PLANT
DIOECIOUS = LOCATED ON DIFFERENT PLANTS
ANGIOSPERM REPRODUCTION
DEVELOPMENT OF MALE GAMETOPHYTE
WITHIN SPORANGIUM OF ANTHER
1 MICROSPOROCYTE (2n) => MEIOSIS
=> 4 MICROSPORES (1n)
MICROSPORE => MITOSIS =>MALE GAMETOPHYTE (1n)
1 GENERATIVE CELL
1 TUBE CELL
RESISTANT WALL
= POLLEN GRAIN
TRANSPORTED BY WIND, WATER OR ANIMALS TO CARPEL
POLLINATION = PLACEMENT OF POLLEN GRAIN ONTO STIGMA
ANGIOSPERM REPRODUCTION
DEVELOPMENT OF FEMALE GAMETOPHYTE
WITHIN SPORANGIUM WITHIN OVULE
1 MEGASPOROCYTE (2n) =>
MEIOSIS => 4 MEGASPORES (1n)
1 MEGASPORE => MITOSIS => FEMALE GAMETOPHYTE (1n)
1 EGG
2 SYNERGIDS
2 POLAR NUCLEI
3 ANTIPODAL CELLS
= EMBRYO SAC
ANGIOSPERMS
DOUBLE FERTILIZATION
POLLEN GRAIN ON STIGMA GERMINATES
SENDS TUBE CELL DOWN STYLE
GENERATIVE CELLS DIVIDES VIA MITOSIS = > 2 SPERM CELLS
TUBE TRAVELS THRU OVARY
THRU MICROPYLE INTO OVULE
INTO EMBRYO SAC
SPERM DISCHARGED
1 SPERM FUSES WITH EGG => ZYGOTE (2n)
1 SPERM FUSES WITH 2 POLAR NUCLEI => ENDOSPERM (3n) = FOOD STORE
ANGIOSPERMS
SEED & FRUIT
OVULE => SEED
OVARY => FRUIT (PERICARP)
PLUS OTHER FLORAL PARTS
SIMPLE FRUIT = 1 FLOWER, 1 OVARY
AGGREGATE FRUIT = 1 FLOWER, MANY OVARIES
MULTIPLE FRUIT = MANY FLOWERS, MANY OVARIES
FLESHY OR DRY
SEEDS DISPERSED BY WIND, WATER,OR ANIMALS
TOPIC 5 - PLANT DIVERSITY, FORM & FUNCTION
READINGS:
PLANT DIVERSITY: PG: 546 - 559; 561 - 572
OVERVIEW OF FORM & FUNCTION: PG: 679 - 682; 688 - 692; 730 - 739
FIGURES DVERSITY & OVERVIEW:
28.25; 29.2; 29.3; 29.4; 29.5; 29.7; 29.9; 29.10; 29.11; 29.12; 29.13; 30.1; 30.2;
30.3; 30.4; 30.5; 30.6; 30.8; 30.9; 35.3; 35.4; 35.7; 35.10; 35.11; 35.20; 35.24;
35.25; 36.1, 37.1; 38.1; 38.2; 38.3; 38.5; 38.7; 38.10; 38.12; 39.16;
TABLES: 29.1; 38.1
Glossary - - Plant Diversty, Form & Function
Diversity: Angiosperm, Anthocerophyta, Anthophyta, bryophyte, Bryophyta, charophyte, Conifers, Coniferophyta, cycads, Cycadophyta, dicot, Ginkgophyta, gymnosperm, Hepatophyta, Lycophyta, monocot, Pterophyta, seed plant, vascular plant.
Overview of Form & Function, aggregate fruit, alternation of generations, anther, antheridium, archegonium,, carpel, coevolution, complete flower, cork cambium, cotyledon, cuticle, dioecious, double ferilization, embryo sac, embrophyte, endosperm, gametangium, gametophyte, fruit, heterosporous, homosporous, lignin, megagametophyte, megasporangium, megasporocyte, meristem, microgametophyte, microsporangium, microsporocyte, monoecious, multiple fruit, ovary, ovule, perfect flower, petal, phloem, polar nuclei, pollen grain, pollination system, seed, seed dispersal , sepal, simple fruit, sporophyte, sporopollenin, stamen, stigma, stoma (stomata), style, thallus, tracheid, vascular cambium, vascular tissue, xylem.