non-vascular land plants (bryophytes)

viridiplantae

monophyletic group within the archaeplastids

• green land plants + green algae

• chlorophytes are within the viridiplantae

around when did plants transition to land?

800 mya

archaeplastids in the tree of life

archaeplastids is the super group

• contains the viridiplantae: green algae and land plants

  • contain the embryophytes: land plants

non-vascular land plants characteristics

• monophyletic in the tree of life

• major and difficult transition - only happened once

• non vascular plants: earliest branching group of land plants (paraphyletic)

what are 4 advantages of plants moving onto land?

1. less predators

2. more direct sunlight (get more energy for photosynthesis)

3. less competitors

4. more access to resources and space

what are 5 challenges of plants moving onto

1. lack of transport mechanisms (can’t get resources as easily)

2. dehydration

3. exposed to more harmful uv radiation

4. gravity, need to build more solid structires

5. dispersal/reproduction (gametes can no longer swim in water)

what are the big 3 key innovations that plants found to survive on land

1. pigments protecting them from uv (chlorophyll, flavonoids, carotenoids, anthocyanins)

2. cuticle to help with dehydration: watertight sealant covering parts aboveground, made of hydrocarbons, lipids and wax

3. reproductive innovations

what are the main 3 reproductive innovations that plants developed to be on land

1. spores encased in tough coat of sporopollenin: resist dessication, disperses by the wind and survives longer

2. protective reproductive organ gametangia: protects gametes from drying and physical damage

3. embryo retention: zygotes develop on the parent plant, female plant nourishes it (sporophyte grows out of gametophyte)

bryophytes basic characteristics

• mosses, liverworts, hornworts

• no vascular tissue or complex transport of nutrients

• no true roots, can grow on rocks/shallow soil

• absorb nutrients and water through ‘leaves’

• stuck near water bodies (need moisture for reproduction)

• no strong cuticle

• small and slow growing

• thin leaves

describe bryophyte reproduction

• alternation of generations

• gametophyte-dominant

• unisex (male of female) or bisexual (both)

• use spores for dispersal (not seeds)

• need water: sperm swims through water to find egg

explain the 5 stages of bryophyte reproduction, specify if the stage is haploid or diploid

1. sporophyte stage (diploid): grows our of gametophyte bed

2. sporophyte produces spores (haploid) via meiosis, released and disperse by wind

3. spores (haploid) land, germinate and grow gametophytes (haploid) via mitosis

4. gametophytes produce gametes (haploid) via mitosis. when enough water, males swim through water columns to find females

5. when found, fertilization occurs and sporophyte (diploid) stage grows

moss characteristics

• fragile, wimpy, thin bodies

• only land plant found on all seven continents

• sphagnum (peat moss): forms when plant doesn’t fully decay (acidic or anaerobic envir.), most efficient C sink on planet - used as fuel