VASUCLAR SEEDLESS PLANTS

Question 1

First adaptations

Answer 1

• Pores (liverworts)stomata (mosses, hornworts) for gas exchange
• Rhizoids for fixation (anchors)
• Hadrom and leptom for transport of water and sap
• Antheridia and archegonia with sterile jacket layer
• Sporopollenin in wall of spores

Question 2

Vascular plants (tracheophytes)

Answer 2

1. Synthesize lignin (cell wall rigid and impermeable)
   a. Lignin = rigidity and impermeability for cell walls
   b. Allows vertical growth
   c. Helps water conduction against gravity
2. They posses’ true water (xylem) and food (phloem) conducting tissue
   a. Xylem—made of tracheid or vessel elements
   i. Dead at maturity
   ii. Lignin in cell wall
   b. Phloem—made sieve elements
   i. Living at maturity
3. Sporophyte is highly branched
   a. Allows for the production of multiple sporangia (incr number of spores)
4. Sporophyte is actual plant lives independent of gametophyte

Question 3

Organization

Answer 3

• Were dichotomously branched axes that lacked roots and leaves
• Evolution led to specialization into
  o Shoot system: stems raise leaves (specialized photosynthetic organs) toward the sun
  o Roots system: anchoring and absorption of water and minerals from soil

Question 4

tissues

Answer 4

o Dermal tissue: outer, protective covering
 Epidermis, phelloderm
o Vascular tissue: conduction
 Xylem and phloem
o Ground tissue: in between

Question 5

Primary growth: Lengthening

Answer 5

• Cell division in the apical meristems of roots and shoots
• Produces the new cells that enable the lengthening of stems and roots
• Primary growth produces primary tissues that form the primary plant body

Question 6

Secondary growth: Thickening (wood)

Answer 6

• Thickening of stems and roots
• Division in lateral meristems
  o The vascular cambium produces secondary vascular tissue (xylem and phloem)
   Embryonic cellsxylem phloem outside cork cambium
  o Cork cambium produces the periderm which replaces the epidermis

Question 7

Conducting tissue: Xylem

Answer 7

• Tracheary elements
  o Dead at maturity (empty)
  o Lignin in their cell walls give support
  o Transport water and minerals
• Tracheids
  o More primitive, first to evolve, present in all vascular
• Vessel elements
  o More evolved, seen in angiosperms (flowering plants) and gnetophytes (funkadoodles)

Question 8

Conducting tissue: Phloem

Answer 8

• Sieve elements
  o Living at maturity (nucleus is degenerate)
  o Soft walls and collapse as the stem thicken
  o Actively transport sap produced by photosynthesis

Question 9

Vascular cylinder (stele

Answer 9

• Central of root or stem in the primary plant body
  o Contains primary xylem and phloem sometimes pith (ground tissues) (slide16)

Question 10

Evolution roots and leaves

Answer 10

• Roots may have evolved from lower portions of stem
  o Retain many primitive characteristics
• Leaves arise as protuberances from apical meristem of the shoot
  o flat to increase photosynthetic surface
  o often bear a bud

Question 11

• Microphylls–leaves

Answer 11

o Smaller with single strand of vascular tissue
o Evolved from outgrowth = vascularized

Question 12

• Megaphylls

Answer 12

o Larger blade with branching veins
o Evolved from planation and webbing of lateral axes

Question 13

reproduction

Answer 13

• All vascular plants are oogamous (motile sperm and big gametophyte)—only male gamete released
• Alternation of heteromorphic generations
  o Sporophyte is more complex and independent of gametophyte for nutrition
  o Gametophyte is small
• Some groups produce one type of spore (homosporous)
  o Leads to bisexual gametophytes
   Often archegonia and antheridia do not mature at the same time (interbreeding)
• Often produce 2 types of spores (heterosporous)
  o Microspores (male) and megaspores (female)
  o Lead to unisexual gametophytes (male and female)
  o Gametophytes develop within the spores (endosporic development)
• Some vasc plants produce seeds
  o Seeds consist of a plant embryo packaged along with food supplied within a protective coat
  o The seed protects the embryo and helps to disperse it and allows it to go dormant
  o Gymnosperms, angiosperms, cycads, ginkgo are seed plants

Question 14

Early vascular plants

Answer 14

• Small stature
• Dichotomously branched
• No leaves or roots only rhizomes w/upright stems
• Sporangia homosporous

Question 15

Rhyniophyta (ancestor)

Answer 15

• Earliest known vas plants
  o Xylem cells with some internal wall thickening
  o Aglaophyton, xylem cells lack wall thickenings
  o Represent intermediary stage

Question 16

Zosterphyllophyta (ancestor)

Answer 16

• Resemble rhyniophytes
• Ancestral to lycophytes (club mosses)
  o Both have lateral sporangia
  o Both groups have xylem cells that mature from the periphery to the center of the vascular strand= centripetal differentiation

Question 17

Trimerophyta (ancestor)

Answer 17

• More complex than rhyniophytes and zosterophyllophytes
  o Lateral branches dichotomize several times
  o Massive vascular strand allowing taller plants
  o Terminal sporangia and centrifugal differentiation of xylem like rhyniophyta
• Psilophyton is believed to be ancestral to monilophytes (ferns and allies) and seed plants

Question 18

Carboniferous (ancestor)

Answer 18

• Ferns and other seedless vas plants like club mosses and horsetails domain swampy forests that formed coal

Question 19

ancestors Christa Thinks Zoey Reeks

Answer 19

carboniferous
trimer
zoster
rhynio

Question 20

lycophytes

Answer 20

• Differentiated into stems roots leaves
  o Leaves = microphylls with single vas strand (defining trait in phylum)
  o Have protostele or modified
• Have lateral sporangia and xylem that differentiates centripetally like zosterphyllophytes
• 3 extinct lineages include small to large trees
  o Dominant during carboniferous period

Question 21

o Lycopodiaceae—club mosses

Answer 21

 Found in arctic to tropics
* Many tropical epiphytic species
 Sporophyte= dichotomously branching rhizome w/aerial branched and roots
 Microphylls arranged in spirals
 Sporangia occur singly on the upper surface of sporophylls
 In some, sporophylls are non photosynthetic and grouped into strobili (pinecone –leaves modified with sporangia)
* Others are photosynthetic and interspersed among microphylls
 Spores (Homosporous) germinate into bisexual gametophytes
* Perms must swim to fertilize the egg
* Cross fertilization is predominant
* Sperm with 2 flagella
* Life cycle slide 35

Question 22

o Selaginellaceae—resurrection plant

Answer 22

 Sporophyte is similar to lycopodiaceae but
* Aeriall shoots may be erect (w/spirally arranged microphylls)
* Or flat (w/opposed-decussate microphylls)
 Sporophylls are arranged in strobili
 Heterosporous
* Microspores produced in microsporangium on microsporophyll
* Megaspores produced in megasporangium on megasporophyll
o Both occur on same strobilus
 Gametophyte develop within the spores

Question 23

o Isoetaceae—quillworts

Answer 23

 Aquatic
 Sporophytes consist of a short underground stem bearing linear microphylls
 Heterosporous
* Spores are born at the base of the sporophylls (similar to microphylls)

Question 24

vascular plant reproduction

Answer 24

sprophyte (2n)–>sporangia–>spore mother cells (2n)–>meiosis–> spores (n)–>gametophyte–> M/F (n)–>fertilization–> zygote (2n)–> embryo–> begin again

Question 25

Monilophyta

Answer 25

form monophyletic group w/seed plants, and both have
o Megaphylls
o Multiflagellate sperm

Question 26

ferns

Answer 26

o Epiphytic species
o 2 kinds sporangia
 Eusporangialarge numerous spores with several layered wall (2% fern)
* Form by division of initials parallel to the surface to form inner and outer series of cells

Question 27

• Leptosporangia

Answer 27

o Smaller, less spores
o Singled layered wall w/ annulus
 Annulus—layer of cells w/unevenly thick walls; as sporangium dries out, annulus contracts causing a tear in the lip cells and ejection of spores
o Form by transverse or oblique division of single initial

Question 28

• Ophioglossales

Answer 28

o Ferns w/eusporangia
o Sporophytes produce a single leaf per year
o Leaf has a sterile portion and a fertile portion where eusporangia are born

Question 29

• Psilotales (whisk ferns)

Answer 29

o Two living genera: Psilotum and tmesipteris
 Tropical and subtropical
 Psilotum resembles rhyniophytes, no roots or leaves
 Homosporous, gametophyte is bisexual
 Gametophyte is subterranean w/mycorrhizaee
* Eusporangia are fused into synangia
o 3 sporangia in Psilotum w/ a scale (reduced megaphyll)
o 2 sporangia in tmesipteris on phyllod (pseudo-leaf)

Question 30

• Marattiales

Answer 30

o Tropical
o Eusporangia fused into single synangium

Question 31

• Equisetaceae

Answer 31

o Small scale like leaves
o Epidermal cells contain silica forming ribs b/w nodes
o Upright joint stems from well developed branched rhizomes (perennial)
 Stems are hollow b/w nodes
o At each node a whorl of reduced leaves (megaphylls) are found
 Branches arise laterally at nodes and alternate w/leaves
o Homosporous
o Sporangia born by groups 5-8 on sporangiophores gathered into stobili
 Elaters help
o Some have distinct sterile (green) and fertile (non photosyn)
o Others have stobili born at the tips
o Gametophyte is green and free lving
 Bisexual/male
 If bisexual, archegonia develop before antheridia to incr cross-fertilization
o Has convergence w/caduarinaceae

Question 32

Leptosporangiate

Answer 32

• Filicales
  o Leptosporangia
  o Homosporous (produce single bisexual gametophyte)
   Gametophyte is flat, photosyn = prothallus
   Temperate species (rhizome survive many years)
   Numerous tree species and epiphytic species in tropics)
  o Have megaphylls (fronds)
  o May occur in clusters (sori)
   Each sorus have several sporangia connected to a placenta
   Be protected by an indusium (covering structure form placenta)
   False indusium = leaf margin that is folded over the sorus
• Marisileaceae and salviniaceae (water ferns)
  o Are only living heterosporous ferns (derived characters)