Chapter 29: Plant Diversity I

Plants originated from

Green algae about 470 Million years ago

About 425 million years ago

Traits of facilitating life on land appeared

What are the three structure of plant

Reproductive structure

Photosynthetic branches

Structure that anchor the plant to the soil

What are three types of plants

• Nonvascular plants

• Seedless vascular plants

• Seen plants

What is the function of plants 

Supply oxygen, food sources and habitat for many other terrestrial organism

The closest relative of plant

Green algae called Charophytes

What are some evidence that algae is plants’ ancestor?

• multicellular, eukaryotic, photosynthetic autotrophs

• have cellulose in their cell walls and chloroplasts containing chlorophyll a and b

Morphological and Molecular evidence of Plant and green algae shared ancestor

• Cellulose-synthesizing membrane proteins are arranged in rings, rather than linear sets

• Structure of flagellated sperm

• Sequence similarities in nuclear, chloroplast, and mitochondrial DNA

Sporopollenin

• a polymer that prevents zygotes form drying out present on charophytes and plants

• Helps to resist harsh environment

Charophytes moving from ocean to land will

• Benefit:  unfiltered sunlight, more plentiful CO2 and nutrient rich soil

• Challenges: Scarcity of water and lack of structural support against gravity

Embryophtes

Plants with embryo

• dependency of the embryo on the parent

Derived Trait of Charophyte from plants

• Alternation of generation

• Walled spores produced by sporangia

• Apical meristems

Derived Trait of plant: What is alteration of generation?

The process which the life cycle of plants alternate between two generations of multicellular organism

• Gametophyte and sporophyte

Gametophyte

Multicellular haploid produces haploid gametes (sperm and egg) by Mitosis

Sporophyte

Multicellular diploid produces haploid spores by Meiosis

Spores develop into

Gametophyte

Fertilized egg develop into

Sporophytes

Diploid Embryo is retained within

The tissue of the female gametophyte

How the nutrients are transferred with embryophytes?

From parent to embryo through placenta transfer cells

Derived Trait of plant: Sporangia

Organ in the plant that produces spores

Derived Trait of plant: Apical Meristem

• Located at the tip of the root and shoot for the cell division

  • The cell divide continuously enabling elongation of roots an shoots for better resource acquisition

Derived Trait of plant: Cuticle 

Waxy covering the epidermis

Derived Trait of plant: Stomata

Specialized cell that allow for gas exchange between the outside air and the plant

Early plants lacked

True toots and leaves making absorption challanging

The fossil suggests that 420 million yeas ago

symbiotic associations with fungi (mycorrhizae) may have helped plants without roots to colonize land

when did the first plant spore appear

470 million years ago

Vascular tissue

Cells join into tube s for the transport of water and nutrients

Vascular plants

Plants with complex vascular system

Non vascular plant

Lack of an extensive transport system

Bryophytes

• name of non vascular plants such as liverworts, mosses and hornwarts

• not a monophyletic group

Seedless vascular plants

Have extensive vascular transport system but does not produce seeds

Seedless vascular plants divided into two clades

Lycophytes

Monilophytes

Lycophytes

Club mosses and their relatives

Monilophytes

Fern and their relatives

The majority of living plants are

Seed vascular plants

What is seed?

Embryo packed within a supply of nutrients inside a protective coat

What are the two group of seen plants?

• Gymnosperms

• Angiosperms

Gymnosperm

Produce seed that are enclosed (naked)A

Angiosperm

• Produce seed that develop inside chambers that originate with flowers

• 90% of living plant species