Lecture #8- Ancestral Vascular Plants

Question 1

What groups do the Embryophytes include?

Answer 1

The Bryophytes and the tracheophytes

-Thought to be monophyletic

Question 2

What did the embryophytes evolve from?

Answer 2

Organism resembling coleochaete

Question 3

What are Trilete Spores?

Answer 3

Spores that have a triangular scar on one surface form having been formed in a tetrad (meiosis)

Question 4

How are triplets spores stuck together?

Answer 4

Stuck together in 4’s which are a product of meiosis

Question 5

What are sieve elements?

Answer 5

They are the conducting cells of phloem

• Food transport
• Soft walls (aka not goof for fossils)

Question 6

What are tracheary elements?

Answer 6

They are the conducting cells of xylem

• water transport
• tracheids and vessels
• rigid (good for fossils)

Question 7

What helps prevent tracheary elements from collapsing?

Answer 7

• thichk walls with lignin

- spiral ridges

Question 8

What is a lycophyte?

Answer 8

Sporic meiosis

Question 9

What is a Stele?

Answer 9

Vascular elements which are located in the central cylinder

Question 10

What is the most common Stele in plants?

Answer 10

Eustele

-had to evolve into the perfect one

Question 11

What is Lignin?

Answer 11

• Complex natural polymer

- Ester and cross linked p-hydroxycinnamyl alcohol

Question 12

Why is lignin decay resistant?

Answer 12

1. Molecule is too large to fit into the active sites

2. Broken down products are toxic

Question 13

Do all plants have the same amount of lignin?

Answer 13

No, all plants have a different proportion

Question 14

How does lignin get broken down?

Answer 14

Enzyme creates a radical which physically breaks down the bonds
-has to do this because compound is to big t find into any enzymatic active site

Question 15

Characteristics of Tracheids (xylem)?

Answer 15

• slender with a tapering end
• rigid or spiral like
• no holes through primary and secondary cell walls
• Came first

Question 16

Characteristics of vessels?

Answer 16

-Tubular with ends containing perforations for continuous vertical connection between cells
-Found in anglos and gametophytes (130MYA)
-

Question 17

What is the oldest known vascular plant?

Answer 17

Cooksonia (414-408MYA)

Question 18

What are protracheophytes?

Answer 18

Not vascular plants

• cells resembles those of mosses
• diploid
• does have a vascular system
• non-living or fossils

Question 19

Characteristics of cooksonia?

Answer 19

• Erect
• Terminal Sporangia
• Sporophytes

Question 20

Characteristics of Rhynia?

Answer 20

• Protracheophyte
• Erect
• Photosynthetic branches (leaves weren’t invented)
• Stomata
• Elliptical sporangia

Question 21

Characteristics of Zosterophyllophyta?

Answer 21

Found 408-370MYA

• lateral sporangia (opened up like purses)
• Mycorrhizal associations with Glomeromycota
• Rhyzoids

Question 22

Characteristics of Lycophyta

Answer 22

• Microphylls and auxiliary sporangia
• have a protostele
• Rhizomes and true roots

Question 23

What are microphylls?

Answer 23

Small leaves

Question 24

in lycophyta where are the sporangia located?

Answer 24

In the armpit of the mycrophylls

Question 25

Since wood wasnt invented, how were the plants able to stand up?

Answer 25

The leaves created structural support on the stem to help hold it up

Question 26

Are lycophytes diploid?

Answer 26

yes, they are sporaphytes

Question 27

What are strobili?

Answer 27

Spore cones produced either at the tips of vegetative shoots or on social fertile stems

Question 28

What kind of spores to lycophytes produce?

Answer 28

one one kind, they are homosporous

-gametes are bisexual (n+n)

Question 29

What type of fertilization do lycophytes go through?

Answer 29

aquatic

-swim from atheridium–> archegonium

Question 30

In the Family Selaginellaceae what kind of spores are produced?

Answer 30

They are heterosporous

• microspores (develop in the microspores and are liberated)
• megaspores (depends on food reserves)

Question 31

What is different about the family Isoetaceae?

Answer 31

• Instead of a stem the have basal swelling = corm
• ->specialized cambium which produces secondary growth
• also have CAM photosynthesis

Question 32

What are the Lepidodendrales?

Answer 32

Tree lycopods (45m)

Question 33

What are Equisetales?

Answer 33

horse tails

• stem dominant organ (has silica)
• Photosynthesizing scale like leaves
• Eustele
• Microphylls

Question 34

What are Monilophytes?

Answer 34

plants with spores and true leaves

Question 35

What kind of spores do Equisetales produce?

Answer 35

They are homosporous

-spores terminate to form bisexual gametophytes

Question 36

What are Elaters and what are their purpose?

Answer 36

-Supposed to help with dispersion of spores, coiled around spores and can absorb water. When they do they uncoil releasing the spore

Question 37

What is special about Psilatum?

Answer 37

Not primitively simplified

• no roots or leaves
• photosynthetic stems
• rhizoids
• endo with glomeromycota
• homosporous

Question 38

What are ferns?

Answer 38

Broad leafed euphilophytes that reproduce by spores

• first group with “true leaves”
• no true wood

Question 39

What kind of spores do ferns produce?

Answer 39

They are almost all homosporous

-all aquatic fertilization

Question 40

What are Sori?

Answer 40

They are found on the back of the fern and what the spores develop in

Question 41

Why are Azolla and Anabaena important?

Answer 41

They grow in rice paddies and have an association with cyanobacteria and fix N for them and the rice

Question 42

Why are ferns evolutionarily important?

Answer 42

Not a lot of fungi eat them