The Plant Kingdom
Key Characteristics of Plants
• Multicellular
• Cell specialization
• Photosynthetic autotrophs
• Sessile
• Alternation of Generations– Sporophyte– gametophyte
Green algae gave rise to plants• Both use the same type
of chlorophyll and assessory pigments
• DNA analysis shows commonality
• Both store food as starch and have cell walls made of cellulose.
Evolutionary Relationship Between Plants and Green Algae
Adaptation to Land
• Lost supportive buoyancy of water
• No longer surrounded by water and nutrients.
• Variation in climate
• Roots or rootlike structures
• Cuticle
• Stomata
• Eventually…..– Vascular tissue– lignin
Requirements for Plants to Survive on Land
Without water, strategies for dipersal of sex cells needed to be
developed
• Sex cells and zygote needed a means of dispersal that was independent of water.
• Protective structures were required to protect the developing embryos.
• The above were achieved with the origin of the seed plants.
Characteristics• Nonvascular
• Lack true roots, leaves and stems
• Rootlike structure s are called rhizoids
• Rely on diffusion and poorly developed conducting tissues to distribute water and nutrients.
• Enclosed reproductive structures– Archegonia– Antheridia
Characteristics of Nonvascular Plants
Reproductive cycle for Bryophytes
Types of Nonvascular Plants
BRYOPHYTA
Hepatophytaliverwort
Vascular Plants(tracheophytes)
• Conducting vessels also provide support.– Xylem– Phloem
Seedless Vascular Plants(reproduce via spores)
Types of Seedless Vascular Plants
PSILOPHTAwhisk ferns
• Epiphytes
• Rootless and leafless
LYCOPHYTAclub mosses
• Produces a sporangia bearing strobilus.
SPHENOPHYTAHorsetails
• Genus: Equisetum• Large deposits of
silica in their leaves.• Jointed stems with
whorled leaf arrangement.
SPHENOPHYTAHorsetails
PTEROPHYTATrue ferns
• Broad leaves called fronds
• Leaflets called pinnae
• Sporangium (sorus pl sori) are formed on the underside of the fronds.
• Unfolding fronds are called fiddleheads.
• Spores are dispersed by the wind.
PTEROPHYTATrue ferns
Fern reproductive life cycle
Seed producing plants
• Major adaptations– Pollen (male gametophyte)– Seeds (embryonic plant)
(male and female gametophyte are greatly reduced in size)
• Two types– Gymnosperms (lack flowers)– Angiosperms (flowering plants)
Characteristics of Vascular Plants With Seeds
Characteristics of Gymnosperms
CYCADOPHYTACycads
• Large fernlike leaves
• Plants are either male or female and produce gametes in large strobilus
CYCADOPHYTACycads
Ginkophyta
• Only one species in present day. Ginkgo biloba• Are resistant to air pollution• Bear male and female cones on separate plants.• Male produces pollen in strobilus-like cones.• Female bears seed which develop a fleshy
outer covering and resemble orange-yellow cherries. (Stinks!)
GINKGOPHYTAGinkgo biloba
CONIFEROPHYTACone-bearing trees
• Most diverse of the gymnosperms: produce seeds in woody cones. Include pine, fir, spruce, juniper, cedar, redwood, yew, and larch.
• Form large forests and have adapted to cold and dry habitat (taiga).
• Protected against water loss by leaves covered with a thick cuticle (cutin) and by covering it’s trunk and branches with bark.
• Conifers are evergreens– They do loose their leaves if aged or damaged.– Keeping leaves allows photosynthesis to begin at the earliest
moment in spring.• Found where nutrients are scarce as they eliminate need
to grow a whole new set of leaves (Deciduous trees lose their leaves).
Needles and Cones
Types of Gymnosperms
• CONIFEROPHYTA
• Cone-bearing trees
Life Cycle of a pine
GNETOPHYTA Can be found in the deserts or mountains of Asia, Africa
and central or South America. • 3 genera• 1. Gnetum : A tropical climbing plant• 2. Ephedra (Shrub-like plants and found in
U. S.)• i. “Mormon tea” Scrubby cone-bearing
plant with scale-like leaves.• a. Source of ephedrine: used to treat
asthma, emphysema, and hayfever.
• 3. Welwitschia (Desert dweller with large tuberous root)
• i. Has only 2 leaves and may live 100 yr.
Ephedra
Welwitschia
Life Cycle of Conifers
ANTHOPHYTAFlowering plants
Characteristics of Angiosperms
Types of Angiosperms
Floral Structure
Ovule Formation in an Angiosperm
Female reproduction
Parts of a Pollen Grain
Pollen Grain Formation
Male reproduction
Double fertilization
Seed Structure
