Secondary Growth in stems
Difference of secondary growth in a mature stem and mature root
Secondary growth in a stem has a pith, and no pericycle
How do angiosperm and gymnosperm vascular systems differ and how does that relate to their ecology
Angiosperms have vessels, but gymosperms dont. This is to prevent embolisms by having a smaller space and use of pits for water to flow. Makes year round growth possible
Most important trait that allowed for complex land plants to evolve
Conductive tissue
When did vascular plants begin to increase in diversity
400 mya
Morphoanatomy (anatomical forms and structures that distinguish the species) of ferns
i dont really know we already did that, fiddleheads maybe
What tissues makes up wood and how are the rings formed
Heartwood vs. sapwood
Heartwood = extra dead non conductive xylem strengthened with resin and tannins, darker color towards the center
Sapwood = conductive xylem, lighter color towards the outside
Characteristics of algal ancestors of land plants
Sporopollenin, chlorophyll a, starch stored in chloroplasts, plasmodesmata, heteremorphs
Advantage of heterospory
allows for greater genetic diversity and prevent inbreeding
Are ferns, and fern allies, monophyletic, polyphyletic, or paraphyletic
Ferns = monophyletic
fern allies = polyphyletic
What is bark and the difference between outer and inner bark
Bark refers to everything outside of the vascular cambium.
Outer bark = dead, protective tissue (dead secondary phloem, old periderm)
Inner bark = mostly live tissue recently produced by the two lateral meristems (secondary phloem, phelloderm, dead phloem, remaining cortex)
What is embolism, and how does plant evolution try to solve it?
When an air bubble inhibits water flow
Morphological, physiological, and reproductive changes that occured with the evolution of land plants
developed vascular tissue, evolved microphyll and megaphyll leaves, shifted to oogamy and matrotrophy, put more energy into protecting expensive stages
What did the earliest lineages of tracheophytes look like?
Resembled algae, no roots, turgor pressure, sporangia on the tips, often dichotomously branched
What is homospory and heterospory? Draw one of their life cycles
Homospory is one spore
Heterospory is two spores
Where and how is the periderm formed?
Forms from the cork cambium and includes the cork, cork cambium, and phelloderm.
As the tree gets older, the periderm starts to form deeper within the stem
Where is primary phloem in a mature stem with secondary growth?
Pushed to the outside as little fibers, or crushed out of existence
How did microphylls and megaphylls evolve and which came first?
Microphylls evolved by the leaf becoming more branched from its nub like ancestral state, became more and more branched until the megaphylls evolved, where those branches formed a webbing that eventually turned into leaves.
Microphylls came first
When did tracheophytes evolve
432 MYA
Why do whisk ferns represent the ancestral condition of tracheophytes
Whisk ferns have microphylls which are closer to the ancestral form
Difference between latewood and earlywood, and what are their ecological implications?
Earlywood = thin walled, lighter wood, larger tracheids to move more water in the spring and summer
Latewood = thick walled, darker wood, smaller tracheids to provide structure in the late summer and fall
What direction are secondary xylem and secondary phloem formed, and what direction is cork and phelloderm formed?
Secondary xylem to the inside, phloem towards the outside
cork towards the outside, phelloderm to the inside
Advantage of oogamy and matrotrophy
keep the egg extra safe
Basic feature of ferns and fern allies
Fronds, rhizomes, sori, annuli, elaters, fiddleheads
Advantage of heterospory
Less risk of inbreeding, genetic diversity, and resource allocation