PLANT DIVISIONS

Plants

• NOTE: We use the

term Divisions
instead of the term
Phyla when
referring to plants.

• Characteristics of

plant kingdom
members

– Alternation of

generations with the
diploid sporophyte
generation dominant
except in bryophytes

Evolution of plants from green

algae

• A certain group of green algae known as the

charophytes have the following in common with
plants.

– Chloroplasts of both have thylakoids stacked as grana

and chlorophyll b and carotene to act as accessory
pigments for chlorophyll a.

– The % of cellulose in both is around 25%
– Similar mitosis and cytokinesis mechanisms
– Similar sperm structure for sperm
– DNA evidence backs this up.
– Body of some charophytes is haploid, but fertilized egg

is retained in the organism and grows and then does
meiosis: clue to how alternation of generations started.

Vascular tissue

– Most division (all

except bryophytes)

have vascular tissue

of xylem (water and

minerals) and

phloem (nutrients).

– Picture shows

vascular tissue in a

leaf in a bundle

known as a vein.

These are the lines

you can see in the

leaf.

Carbon dioxide

• Plants lowered the levels of carbon dioxide from 25X

current levels to current levels over a period of 100

million years as they adapted to and spread on land.

Invasion of land

• Stomata
• Cuticle
• Lignin: bonds to cell wall

cellulose to add strength and
waterproofing

• Vascular tissue: xylem and

phloem

• Roots: absorb nutrients and

water vs. rhizoids of moss
and holdfasts of algae that
don’t.

• Seeds: dormancy
• Fruit: spreading seeds
• Flowers: cross pollination

Cuticle

– A waxy cuticle covers parts exposed to air to prevent

dessication. Openings in the cuticle (stomata) allow
for gas exchange and are controlled by the guard cells.

Guard cells

Cuticle, Dermal tissue, ground

tissue, and vascular tissue

Flagellated sperm vs. pollen

• The more primitive plants have flagellated sperm

that allow them to swim to the egg. This means
that the mosses, ferns, and other primitive plants
require water to have fertilization.

Fern sperm

Types of
pollen

Plant Divisions: Bryophyta

• MOSSES
• Dominant gametophtye

generation (green)

• Also includes liverworts

and hornworts

• Need sperm to fertilize egg
• NO vascular tissue limits

height of the plant and
therefore have no true
roots, stems, or leaves.

• haploid spores are made

by meiosis in the
sporangium of the
sporophyte.

Moss
sporophyt
e

Other Bryophytes

Liverworts

Hornwort

Gametophyte

s

• Antheridium Archegonium
• Male gametophyte

Female

gametophyte

• Makes sperm makes egg

Lycophyta: club
mosses,lycopods

They have vascular tissue.
Inconspicuous gametophyte can live
underground for ten years.

• Lycopodium

Club

mosses

Sphenophyta: horsetails

Once occupied the niche of trees before conifers

and flowering plants existed

• They are homosporous

Pterophyta

• Homosporous: create one spore that

is bisexual.

• Vascular tissue but no seeds: allows

them to get taller, but limits them to

shady moist areas for reproduction.

• Fronds: big “leaf like” arrangement
• Fiddlehead: emerging sporophyte
• Spore making sporangium on

underside of fronds when reproducing.

Ferns

• Fiddlehead
• Sporangia

on
underside
of frond

• Fronds
• Bisexual

gametophy
te

Gymnosperms (naked seeds) have

no flowers: gingko, cycad, and

conifers

Coniferophyta

• Redwoods, firs, pines, yews,

cypresses

• Naked seeds: not enclosed in fruits
• Wind pollination (NEEDS A LOT)
• Seeds, vascular tissue
• No flowers
• Often needles thick with cuticle and

small in size to limit transpiration.

Seed cones vs. pollen cones

Seed cones

seeds

Pollen cones

Oldest and largest

• Redwoods (400 feet tall) bristlecone pine (4600

years old)

Anthophyta

• Flowering plants
• Flower will develop into fruit that is used

for seed dispersal via wind, water, or
animal.

• Pollination can be by wind, bird, bat, insect.
• Most advanced (recent)
• Gametophyte is reduced and within the

flower.

• Most diverse: grasses to trees

Seed dispersal

Flower structure: reproduction

organ of some plants

Double Fertilization

• Generative nucleus becomes two “sperm” through

mitosis. First sperm fertilizes egg in the ovule and

second sperm fertilizes polar nuclei to become

triploid endosperm. Endosperm will become “food”

for seed.

Prefixes for plants

• Mega and Arche are female
• Micro and Anther are male
• Microgametophyte = pollen (becomes

sperm)

• Megagametophyte = makes eggs
• Atheridium: anthers make male gametes
• Archegonium: place where eggs are made

Monoecious (one house)

flower

• Name the

parts

• Dioecious:

Two
houses/
male and
female
flowers

Parts: functions

• Female (carpel/pistil)

– Stigma is sticky “top” that collects pollen
– Style is connection between stigma and ovary.
– Ovary is where eggs are made in the ovules

• Male (stamen)

– Anther makes the pollen
– Filament holds anther away from female part to

allow for wind/insect to carry pollen away

• Petals (collectively called corona): attracts

pollinators

• Sepals (collectively called calyx); protects the

bud before blooming

Fruit

• The ripened ovary becomes the fruit

after the fertilization of the egg and
formation of the seed.

• Single fruit: one flower with one pistil
• Aggregate fruit: one flower with

mutliple pistils

• Multiple fruit: multiple flowers fuse to

make one fruit

Fruit types

• Simple

aggregate

multiple

Review

• What division of plants has no vascular

tissue?

• What is made by the archegonium?
• What part of the flower “catches the pollen?
• What is one gymnosperm other than

coniferophyta?

• What part of a flower becomes the fruit?
• Where do you find the sporangium on a fern?

More review

• What process makes the gametes in a plant?
• What division of plants includes the tallest

trees?

• What is the purpose of the fruit?
• What is the food of a seed called?
• What group of green algae are the closest

relatives to plants?

• What does the cuticle prevent?
• How many flowers lead to an aggregate fruit?
• What is true of plants that are heterosporous?