Download Chpt 22 Plants with seeds - Kingdom Plantae

Chpt 22 – Plants with seeds
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Kingdom Plantae
Phylum Tracheophyta
Subphylum Spermopsida
o Plants with seeds
And roots
And stems
And leaves
And have vascular tissue
Root – function is to absorb water and minerals
o Also, roots anchor the plant
Stems – function is to hold out leaves to the Sun
o Are also conduits for vascular tissue
o Have to be sturdy and rigid
Leaves – function is to be the site for photosynthesis
o Have a large flat surface area
o Leaves contribute to water loss through gas exchange
o Most leaves have developed a protective layer
Cuticle – an acellular waxy layer that protects from water loss.
Vascular tissue
o Transport water, minerals and the products of photosynthesis around the plant
2 types
• A) Xylem – carry water and mineral
o From the roots to the leaves (up)
o Have thick cell walls
o Mostly made up of dead cells
• B) Phloem – carry the products of photosynthesis around the plant
o Can transport up and down the plant
o These cells are alive.
Seeds – the solution to the problem of reproduction without needing water
o All Spermopsida have life cycles with alternation of generation.
o The evolutionary trend is to have a smaller, less prominent gametophyte
Only a few cells large
o And a larger more prominent sporophyte
The plant that we see are the sporophytes
o The reproductive structures that house the female gametophyte are called flowers or cones
(depending on the class of the plant)
o The male gametophyte is contained in a tiny structure (only 1 cell) called pollen
o Without water, the pollen needs methods to get to the female gametophytes – called
pollination
o Seeds are the structures that protect the zygote after fertilization
o The zygote grows into a tiny embryo, then stops growing and it is covered by a seed coat
protecting it and a food supply for its later growth
o A seed can remain dormant for weeks, months or even years
o It can even survive extreme conditions such as digestion or a fire, or freezing
The Evolution of Seed Plants
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As the environment on Earth changed, the plants changed
o Some plants prosper while other plants died out
This gives rise to new plant species
o Mosses lead to ferns
o Ferns lead to seed ferns
Seed fern – resembles a fern but reproduces with seeds
All seed ferns are extinct
Of the remaining seed plants:
o There are 2 groups
1 – Gymnosperm –
• Gymno – naked
• Sperm – seed
o Therefore gymnosperms are plants that produce seeds that do not
have a seed coat for protection
• The male and female reproductive structures are called cones
• Female cones produce eggs
• Male cones produce sperm as pollen
3 examples of gymnosperms to know
• A) Subclass Cycad – palm-like plant
o Reproduce by cones
o Found in tropical and subtropical areas
• B) Ginkgoes – common during the time of the dinosaurs
o Only one species left
o Lose their leaves in winter
• C) Conifer – commonly called evergreens
o Most abundant gymnosperm
o Leaves have adapted into long thin cuticle covered needles
o They have 2 types of reproductive cones
Male pollen cone
Female egg/seed cone
• After fertilization the zygote grows into a seed
between the cone scales
2 – Angiosperm – aka flowering plants
• Reproduce with flowers
• Seeds are contained by a protective wall that develops into a fruit.
• Angiosperms are the most widespread land plants
• 2 subclasses of angiosperms
1. monocotyledonae – monocots
Ex – corn, wheat, lilies, palms, grasses
• Have only one cotyledon – leaves of the embryo or seed leaf
2. dicotyledenae – dicots
Ex – roses, clover, tomatoes, oaks, maples, daises
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have 2 cotyledons or seed leaves
***Monocots and dicots have other distinguishing features:
1. Veins in a monocot leaf are parallel. Veins in a dicot leaf are branching.
2. Monocot flower petals are multiples of 3, dicot flower petals are multiples of 4 or 5.
3. Monocot stems have vascular bundles scattered through the stems. Dicots stems have vascular
bundles arranged in a ring near the outside of the stem. P. 499
4. Monocot roots have xylem and phloem that alternates in rings, dicot roots have a mass of xylem that
forms an X in the center of the root and phloem between the arms of the X. P. 495
5. Monocot stems do not necessarily grown thicker each year, dicot stems can (ex. Trees)
Co evolution – Flowering Plants and Animals
- As plants relied less and less on H2O for reproduction, they started to reply more and more on other means
of getting pollen to a flower.
- Plants and animals co-evolved to mutually benefit each other.
- Pollination started to require more than just wind
Ex. Insects, birds, animals
- Flowers started to evolve ways to attract specific animals for pollination
Ex. Fragrances, nectar, fruits, UV colors.
Seed Dispersal
- Plants now needed a way to prevent competition for resources.
- New plants needed to find a place to grown
- Plants use several means to dispense seeds
- Wind – parachutes
- Animals – burs – transport
- Digestion – fruit
P. 484 – 485 MC, TF, WR