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Chapter 21
Main Ideas:
1. Adaptations to environmental changes on Earth contributed to the
evolution of plants.
2. Nonvascular plants are small and usually grow in damp
environments.
3. Because they have vascular tissues, seedless vascular plants
generally are larger and better adapted to drier environments
than nonvascular plants.
4. Vascular seed plants are the most widely distributed on Earth.
I. PLANT EVOLUTION & ADAPTATIONS
A. Basic Characteristics
1. multicellular eukaryotes
2. autotrophs-->how?-->
3. thick cell wall made of
4. have a cuticle-->
B. Plant Evolution
1. plants provide O2, food, clothing, furniture
2. evidence that multicellular land plants & present day green algae
share a common ancestor
a.
b.
c.
d.
C. Plant Adaptations to Land ENVRs
for plants to evolve & survive, they had to adapt to their ENVR
plants that lived near water thrived, but as the ancient oceans
receded the plants had to adapt
1. cuticle-->
a. lipid doesn't dissolve in water
b.
2. stomata
a.
3. most plant stems contain vascular tissues-->
a. plants that have vascular tissues are called vascular plants=
b. allows materials to be transported much more quickly
c. vascular tissue also provides support
d.
1.usually only a few cells thick & water/nutrients travel via
diffusion/osmosis
e.
4. seed-->
a. protects embryo from drying out
b. land plants reproduce from seeds/spores
5. reproductive strategies
a. some land plants require a film of water to reproduce
b. seed plants have adaptations that allow plants to reproduce w/o
the presence of water
D. Alternation of Generations
a.
b. gametophyte generation-->produces gametes & they are
haploid(n)
c. sporophyte generation begins w/fertilization & goes through cell
division & mitosis
d. the sporophyte undergoes meiosis-->haploid(n)
e. 1 generation is usually dominant & it accounts for most of the
plant’s life
II. Nonvascular Plants
A. Diversity of Nonvascular Plants
a.
b.
c.
1. Bryopohyta-->mosses
a. non-vascular
b. water & nutrients move via diffusion & osmosis
c. some mosses have elongated cells that trasnport water &
sugars
d. spores formed in capsules
e. peat moss can be used as fuel
2. Anthocerophyta-->hornworts
a. sporoohytes resemble horns of an animal
b. non-vascular-->grow in damp, shady ENVRs
c. water & nutrients move via diffusion & osmosis
3. Hepaticophyta-->liverworts
a. classified as thalose/leafy
1. thaloseleafy; resembles a fleshy/lobed structure
b. non-vascular-->only grow in moist ENVRs
c. water & nutrients move via diffusion & osmosis
d. lack DNA sequences that most other land plants containmost
primitive of land plants
III. SEEDLESS VASCULAR PLANTS
A. exhibit greater diversity in form & size
B. strobilus
1. Lycophyta-->club mosses
a. vascular plants adapted to moist ENVRs
b. have stems, roots, & leaves
c. dominant sporophyte generation
d. epiphyte
1. if anchored in treetops it can create another habitat for
insects/small animals
e. large component of Paleozoic forests
2. Pterophyta-->ferns & horsetails
a. most diverse of non-seed vascular plants
b. abundant during in Paleozoic & Mesozoic forests
c. have leaves called fronds that vary from 1 cm to 500 cm
d. most species grow in tropics
e. if H2O is scarce, ferns can prod. sporophytes w/o
fertilization
f.
1. rhizome=
g.
h.
IV. VASCULAR SEED PLANT
A. Prod. Seeds
1. ea. seed contains a tiny sporophyte surrounded by connective
tissue
2. seeds have 1/more cotyledons
3.
4.
B. Diversity of Seed Plants
1. variety of dispersal adaptations
a. imp. b/c it limits competition b/t new plant, its parent, &
other offspring
2.
a.
b.
1. Cycadophyta-->cycads
a. abundant during Mesozoic Era
b. palmlike trees w/scaly trunks
c. produce male & female cones on separate trees
d. cones-->
e. seeds produced in female cone & pollen produced in male cone
2. Gnetophyta-->3 genera
a. Gnetum-->tropical trees & climbing vines
b. Ephedra-->grow in desert & arid regions
c. Welwitschia-->only 1 species; found in deserts of SW Africa
3. Ginkgophyta-->ginkgoes
a. small, fan-shaped leaves
b. has male & female reproductive structures on separate trees
c. hardy-->resistant to insects & pollution
4. Coniferophyta-->
a.
b. identified by the characteristics of their cones/leaves
c. bristlecone pine trees are the oldest in the world
d. Pacific yew=source of cancer fighting drugs
5. Anthophyta-->
a. largest, most diverse group of seed plants
b. produce flowers which usually contain 1/more seeds
c. life spans
1. annual
2. biennal.
3. perennial