Non-Vascular Plants

1
Non-Vascular Plants
2
Evolution of Land Plants

• Land plants evolved from green algae
• The green algae called charophyceans are the
  closest relatives of land plants
• Comparisons of both nuclear and chloroplast genes
• Point to charophyceans as the closest living
  relatives of land plants

3
Origin and Diversification of Plants

• Fossil evidence indicates that plants were on
  land at least 475 million years ago
• Whatever the age of the first land plants those
  ancestral species gave rise to a vast diversity
  of modern plants

4
Plant Evolution
5
Bryophytes

• Life cycles of mosses and other bryophytes are
  dominated by the gametophyte stage
• Bryophytes are represented today by three phyla
  of small herbaceous (nonwoody) plants
• Liverworts, phylum Hepatophyta
• Hornworts, phylum Anthocerophyta
• Mosses, phylum Bryophyta

6
Bryophytes

• Nonvascular (pass water cell-to-cell)
• Seedless (reproduce by spores)
• Low growing
• Phylum Bryophyta (also includes liverworts
  hornworts)
• Grow on moist brick walls, in sidewalks, as thick
  mats on forest floors, and on the shaded side of
  trees

7
Bryophytes

• Can survive periodic dry spells, reviving when
  water becomes available
• Require water for fertilization so sperm can swim
  to egg
• Rhizoids (root like structures) anchor mosses
• Have waxy covering called cuticle on aerial parts
  to prevent desiccation

8

• Dominant form of a moss is a clump of leafy
  green gametophytes 
  (photosynthetic)
•  Moss alternates between a haploid (1n)
  gametophyte and diploid (2n) sporophyte
• Gametophyte generation produces gametes (eggs
  Sperm)
• Sporophyte generation forms at the top of the
  gametophytes and produces spores 
• Stalk-like sporophytes lack chlorophyll
• Capsule at the top of the sporophyte forms
  haploid (1n) spores

 a Diploid (2n) sporophyte stage (contains two
sets of chromosomes, one from male and one from
female) and a Haploid (1n) gametophyte stage
(contains one set of chromosomes) This type of
life cycle is called Alternation of Generations
9

• Sexual reproduction in Moss
• Moss produce 2 kinds of jacketed gametes --- eggs
  sperm
• Egg producing organ is called the archegonium
• Eggs are larger and nonmotile
• Sperm producing organ is called the antheridium
• Sperm are smaller, flagellated cells
• Antheridia archegonia are both part of the
  gametophyte plant
• Fertilization can occur only during or soon
  after RAIN  when the gametophyte is covered with
  Water
• Sperm swim to the egg by following a trail of
  chemicals released by the egg in the water
• Fertilization produces a zygote that becomes
  a sporophyte
• Mature sporophytes produce homosporous spores
  (all the same type)
• Mature capsules open release spores spread
  by wind
• Spores landing on moist places germinate
  into protonema that become new gametophytes

10
Only the zygote is 2n
11
Liverworts

• Have no true roots or shoots
• Non- vascular
• Require water to reproduce
• Have no or very little leaf structure
• Cannot live in sporophyte form

12
Hornworts

• Free-floating aquatic plant, or land plant
• No vascular tissue
• No true leaves or roots
• Can live in both gametophyte and sporophyte forms

13
Mosses

• Land plant
• Most have no vascular tissue
• Majority of life spent in gametophyte stage
• Need water to breed
• No leaves or roots
• Sporophytes are capsules on stalks