still under construction

Psilotum

Lycopodium

Equisetum

Fern

Selaginella

quiz quiz Survey

Migration to Land Hypothesis
  1^o vs 2^o invaders (fungi)

Green Algae Land Plants
 
 

Major Problems
 

1. Obtaining reliable source of H2O	Absorb
2. Retaining H2O	Dessication
3. Transport H2O, ions and food	Conduct
4. Gravity	Support, no bouyancy
5. Protect and dispersal	air borne, later animals

Also:
1. greater range of temperature fluctuation
2. more light

Strategies

1. Avoid  - e.g. live in wet areas on land  -  liverworts

2. Evade - e.g. short life cycle, dormant

3. Cope

Dual environment  soil -- air

Adaptations

Why selected for ?
What adaptive significance? selection pressure ?
 

Not Pre-adaptation !

Adaptations that help water plants live in water that also made land possible

Analogy -- space technology suited to land

No adaptive significance in normal conditions
     but
Might be significant in special conditions

Example:

Seasonal drought
H₂O level drops
Small ponds dry completely
    Plants die
    Must reinvade

Waterproof covering (cuticle)
       last longer --- out produce
      survive mild drought (head start following season)
Windblown spores
      Move to larger ponds or wet areas
 

Lower Vascular Plants

Like the Bryophytes

Multicell sex with sterile cells antheridia  + archegonia

Flagellated, free-swimming sperm (Land -- but still dependent on free H₂O)

Non-motile egg

Embryo

2N retained in early development

Nourished

Protected

Alternation of multicellular sporophyte and gametophyte

Most are homosporous (Selaginella is heterosporous)

Most have root, stem and microphyllous "leaves" (megaphyll in fern)

Vascular tissues - xylem and phloem

2N Dominant

2N free-living at maturity (N also free living, non-green saprophyte in some)

Homospory (in most)

No seeds

Lack cambium

Lower Vascular Plants - Ferns and Allies
  Vascular tissue
  2N Dominant
  Most homosoporous
  No seeds
  Lack cambium

Division	Psilophyta	Lycophyta	Sphenophyta	Pterophyta
.	Whisk Fern	Club Mosses	Horse Tail	Ferns
.	Psilotum	Lycopodium	Equisetum	Polypodium
Root	-   *rhizoid	root	root	root
Leaf	+,- microphyll	microphyll	microphyll, whorls	megaphyll, alternate
Stem	dichotomous	.	jointed, ridged	.
Sporangia	short branch or branch tip,3 lobes, 3 chambers, synangium	axillary or upper base of leaf	sporangiophore	sori
.
		Selaginella
Gametophyte	subterranean	subterranean or green	subterranean  or green	green
Sperm	multiflagellate	biflagellate	multiflagellate	multiflagellate
Life Cycle	Psilotum	Lycopodium Selaginella	Equisetum	Fern

*rhizome with endomycorrhizal zygomycete   Table of characteristics- Konig   Key
Phylum directory
 
 
 
 
 
 

Psilotum
 

gopher://wiscinfo.wisc.edu:2070/I9/ .image/.bot/.130/Fern_Allies/ Psilophyta/Psilotum_habit	gopher://wiscinfo.wisc.edu:2070/I9/ .image/.bot/.130/Fern_Allies/ Psilophyta/ Psilotum_enations_and_sporangia	gopher://wiscinfo.wisc.edu:2070/I9/ .image/.bot/.130/Fern_Allies/ Psilophyta/Psilotum_sporangium_d
		Life Cycle Diagram

Lycopodium

http://www.csdl.tamu.edu/ FLORA/Fern&Gym/ F&G004.jpg	gopher://wiscinfo.wisc.edu:2070 /I9/.image/.bot/.130/Fern_Allies/ Lycophyta/Lycopodium/ Plant_with_Strobilus_d	gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/ Fern_Allies/Lycophyta/ Lycopodium/Sporophylls_d
	gopher://wiscinfo.wisc.edu:2070 /I9/.image/.bot/.130/ Fern_Allies/Lycophyta/ Lycopodium/Strobilus_d

Equisetum

gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/Fern_Allies/ Sphenophyta/Equisetum/ Equisetum_arvense_d	gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/Fern_Allies/ Sphenophyta/Equisetum/ E._laevigatum_KS
gopher://wiscinfo.wisc.edu:2070/I9/ .image/.bot/.130/Fern_Allies/ Sphenophyta/Equisetum/ Strobilus_sporangiophores_d	gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/Fern_Allies/ Sphenophyta/Equisetum/ Strobilus_composite_d	gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/ Fern_Allies/Sphenophyta/ Equisetum/Equisetum_spores

Fern
 

	gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/ Ferns/Gametophyte_Images/ Composite_view_d
http://raider.grcc.cc.mi.us/ biosci/pictdata/bi103/560-ml.jpg	fern sperm   sperm	http://raider.grcc.cc.mi.us/ biosci/pictdata/bi103/560-fl.jpg
gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/ Ferns/Gametophyte_Images/ Antheridium_ls_d_130		gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/Ferns/ Gametophyte_Images/ Sperm_and_achegonium_d

 

gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/ Ferns/Sporophyte_images/ Fern_labeled	gopher://wiscinfo.wisc.edu:2070/I9/ .image/.bot/.130/Ferns/ Sporophyte_images/ Circinate_Vernation/ Osmunda_cinnamomea_KS Circinate vernation	gopher://wiscinfo.wisc.edu:2070/I9/ .image/.bot/.130/Ferns/ Sporophyte_images/ Adiantum_rhizome_leaf_gap_c
gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/ Ferns/Sporophyte_images/ Dicksonia_rhizome_400_x_d	gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/ Ferns/Sporophyte_images/ Cyrtonium_indusium_xs_d
gopher://wiscinfo.wisc.edu:2070 /I9/.image/.bot/.130/Ferns/ Sporophyte_images/ Cyrtomium_sori_with_indusia_d	gopher://wiscinfo.wisc.edu:2070/I9/ .image/.bot/.130/Ferns/ Sporophyte_images/ Sporangium_transverse_annulus_d	http://www.umanitoba.ca/ faculties/science/ biological_sciences/ lab7/images/sori.gif

 

Ferns   Ferns - life cycle, relationships		http://www.umanitoba.ca/ faculties/science/ biological_sciences/lab7/ images/ferngamwspor.gif
Life cycle

Circinate vernation
Circinate -- rolled in coil on its axis with apex in center  cir = round
Vernation --- arrangement of leaves in a bud              vern = spring
 

Heterospory vs Homospory
 
 

Homospory	Heterospory
Most Ferns, Psilophyta, Sphenophyta, some Lycophyta	Selaginella, a few ferns (Salvinia, Marselia), all *seed plants
one type of spore	two types of spoes, often large + small   Megaspores   Microspores
one type of sporangium	two types of sporangia   Megasporangia   Microsporangia
one kind of gametophyte	two types of gametophytes   megagametophyte   microgametophyte
bisexual gametophyte	Unisexual gametophyte    most important distinction

* seed plants are functionally heterosporous (megaspore size may be <, > or = microspore)
  Megaspore size reduced when became permanently retained in sporangium

Selaginella Lycophyta-Selaginellales-1    nice information and images

gopher://wiscinfo.wisc.edu:2070/I9/ .image/.bot/.130/Fern_Allies/ Lycophyta/Selaginella/ Selaginella_apoda_KS	gopher://wiscinfo.wisc.edu:2070/I9/ .image/.bot/.130/Fern_Allies/ Lycophyta/Selaginella/ Selaginella_branch	gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/ Fern_Allies/Lycophyta/ Selaginella/Strobilus_d
http://www.botany.hawaii.edu/ faculty/webb/BOT201/ Selaginella/LeafCloseUp-3-Lab.jpg	http://home.uleth.ca/ bio/bio1020/images/sel4b6.jpg	gopher://wiscinfo.wisc.edu:2070/ I9/.image/.bot/.130/ Fern_Allies/Lycophyta/ Selaginella/Sporophylls_d
Gametophyte Development http://www.botany.hawaii.edu/ faculty/webb/BOT201/ Selaginella/ Megagametophyte240Lab.jpg	http://www.botany.hawaii.edu/ faculty/webb/BOT201/Selaginella/ GametoSporo240Lab.jpg	http://home.uleth.ca/bio/ bio1020/images/sel6b6.jpg
http://www.botany.hawaii.edu/ faculty/webb/BOT201/ Selaginella/ArchClose400Lab.jpg		Life cycle Life cycle - do it yourself

 

Microphyll - no leaf gap	Microphyll-  no leaf gap
Sporophyll - spore bearing leaf	Sporophyll - spore beariang leaf
Megasporophyll	Microsporophyll
Megasporangium	Microsporangium
Megaspore mother cell	Microspore mother cell
meiosis	meiosis
Megaspores     large     thick-walled    1-4 per sporangium    white to yellow	Microspores     smaller     thin-walled     numerous     orange

 

Selaginella
  Points of special note (for evolution toward land plants)

1. Gametophytes retained with spore wall - -  endosporic

2. Gametophytes reduced and dependent

3. Gametophytes unisexual

4. Less dependence on free water for fertilization

5. Role of gametophyte reduced to protection and nutrition of embryo

Preface to Seed Plant

Greater adaptation to terrestrial life

Increased protection of sporangia
   Megaspores retained
   Microgametophyte released, megagametophyte retained  (by parent sporophyte tissue -- within integument of ovule in gymnosperms, within integuments of ovule and wall of carpel in angiosperms)

Reduction of gametophytes
  Size decreases
  Vegetative cells reduced, essentially lost
   Sterile jacket reduced or lost
   Increased protection (enclosed)

Free water not needed for fertilization
  Free swimming sperm --> pollen tube + flagellated sperm  --> pollen tube + sperm nuclei

Nutrition of embryo
     More reliable food source

Resting stage (seed)
 

Microphyll	Megaphyll
"small" + "leaf"	"large" + "leaf"
Psilophytes (but not Psilotum), Lycopods, Horsetails	Fern, Seed plants
Usually small	often large
simple	simple or compound (often blade & petiole)
1 or no Vascular strand   central   unbranched	1 or more vascular strands   branched
typically on protostele  Equisetum has microphyll on eustele	typically on siphonostele (hollow cylinder)  or eustele (strands)
mesophyll of uniform parenchyms	often palisade and spongy
may have stomates	stomates typical
No leaf gap	leaf gap

 
 

Find a lower vascular plant for Lab    Where to look At this time of year you may have difficulty collecting lower vascular plants growing outdoors. I  have several ferns growing in my yard that retain their foliage so that I can find them even after most other plants have lost their leaves. Spike mosses grow as weeds near one edge of my vegetable garden. Also, I know where I can collect club mosses on some land that I own. However, I suggest that you look for one of the many ferns that are grown as houseplants. Perhaps ask an aunt, grandparent or friend who does have ferns as houseplants if you can take one of the compound leaves for your class project.   What to look for Ferns grow well as houseplants is the proper varieties are selected and provided with suitable conditions. Most ferns have compound leaves (fronds) that are highly dissected. Young fronds are curled and unroll as they mature. Stems are often short and coated with brownish "fuzz" or scales. Spore producing structures may be seen on the lower surface of some fertile fronds. If the fern has spores I will appreciate your bringing a leaf with spores to lab.  You need collect and bring to lab only a single leaf. If you have access to other lower vascular plants you may elect to bring a club moss, spike moss, etc. instead of a fern.