Lesson 9: Introduction to Plants Flashcards
What are plants?
Plants are one of the most diverse species; they are extremely different from each other in height, for instance
How did plants evolve?
evolved from charophytes, a group of protist green algae
Plant characteristics
- multicellular
- eukaryotic
- almost all perform photosynthesis
- cell walls made of cellulose
- sessile (fixed in one place, immobile)
- reproduce by alternation of generations (alternation between diploid and haploid forms)
types of plants: Bryophytes
- mosses are the most familiar group
- evolved many features which make other terrestrial plants successful (this does not include a vascular system; instead they depend on simple diffusion, osmosis, and active transport to survive)
- they have rhizoids, not true roots (this accounts for their limited capacity for absorption and lack of anchorage)
mosses: pioneer plants
- this means that they are often the first to establish themselves on previously uninhabitated areas
–> i.e: rocks, soils
–> as they die and decompose, they enhance the environment
–> i.e: provide organic matter that enhances the soil and facilitates other plant growth
Example: peat moss
–> useful moss!
- pioneers in ecosystems
- used in gardening
- used as a fuel in europe and asia
- can be chemically altered to form coal
- can be used as antiseptic
- used to mop up oil spills
- absorbent- was used as surgical dressings in WW1, diapers for babies and in feminine hygiene products
Types of plants: tracheophytes
–> ferns are tracheophytes- plants that have a vascular system
- earliest vascular plants to evolve
- ferns are the most well known example
–> most recognizable feature of the fern is the leafy portion called a FROND
Ferns: ecological succession
–> Play an important role in ecological succession (i.e. process of change in the species that make up an ecological community over time)
- Also pioneer plants
- i.e. can grow on bare exposed rocks and in open bogs and marshes
- Can grow in volcanic ash or after forest fires
Example: fiddlehead ferns
–> You may recognize the fiddlehead fern
- These are young curled fronds of young ferns that are harvested as a vegetable
- They have high levels of antioxidants, iron, fiber, omega-3 and omega-6 fatty acids
Types of plants: Stermatophytes
–>Seed plants are called spermatophytes
- Subdivision of tracheophytes (aka. Vascular plants)
–>They have roots, stems, and leaves
- HUGE variety in colours, odours, shapes and sizes
–> Most recently evolved
- Reproduction NOT dependant on water
- They have a seed which contains a plant embryo
types of spermatophytes: gymnosperms
–>Include pines, junipers, spruces, cedars and other cone-bearing plants
–>Most have evolved thin- needle like leaves
- Help plant survive harsh dry, hot and cold weather
–>Needles covered in a hard waxy cuticle
–>Deep penetrating roots
Example: Yew
–>Paclitaxel (a well known natural source cancer drug) can be isolated from the tree bark and needles of the Yew tree
- Sometimes also called by its original brand name Taxol
- This is used as a chemotherapy drug
- Used in the treatment of ovarian, breast, non small cell lung and Kaposi’s sarcoma cancers
Types of spermatophytes: angiosperms (flowering plants)
–>Over 250,000 species of angiosperms
- More than all other plant divisions combined
- Species are discovered almost daily
–>All are tracheophytes
- Because they have vascular tissue
–>All will have flowers and fruit for reproduction
Example: Rice
–> Rice is the seed of certain grass species
- This is a widely consumed staple food for a large part of the human population
- Large portion are grown for human consumption
- There are many varieties
