FRST 303 Lectures 4 then 3

C

Why have trees evolved to grow tall

Better access to sunlight (competition)

What tree of the day is this and what makes it special?

Coast redwood and it is the tallest tree species in the world

Why is it used for fences, decks, and outdoor furniture?

Because it is decay resistant

What tree species do these seeds and cones belong to?

Of course, coast redwood

What are stem cells and what are they called in plants?

Undifferentiated cells that can continue to divide for hundreds or thousands of years that are called meristematic cells in plants

Where are the two types of meristematic cells?

Shoot apical meristems at the stem and branches and root apical meristems

True or False: The root apical meristems are at the root tips just comme how the shoot apical meristems are at the tip of stems and branches

False. While the shoot apical meristems are at the tip of stems and branches, the root apical meristems are not at the root tips so as to not get torn by the soil

So, what is at the root tip?

Slimy cells called mucilaginous cells

What grows first?

The roots

What Tree of the Day is this?

Monkey puzzle or pehuen (A.A)

Why is the tree important to the Pehuenche people in Chile?

The seeds are a staple part of their diet and they considered it sacred

True of False: All gymnosperms (naked seeds without fruits) are conifers

False. All conifers are gymnosperms, but not all gymnosperms are conifers

True or False: Most conifers, but not all, are evergreens (have leaves on throughout the seasons)

True

True or False: Not all evergreens are conifers

True. There are evergreen angiosperms

True or False: All conifers have cones

False. Most, but not all, conifers have cones

What are the 2/4 phylum of gymnosperms that we are expected to know?

Ginkophyta (1 species remember) and Coniferophyta (600 conifer species)

What is the seed structure of conifers (5 things)?

1. Embryo (2N)

2. Megagametophyte (N): Provides nutrients for the seed to germinate and us if we decide to eat the seed

3. Nucellar cap

4. Cotyledon

5. Seed coat

Where are seeds cones and pollen cones located relative to each other?

On the same tree, with the pollen cones lower on the tree for the wind to carry pollen up to the seed cones

True or False: This is a pine cone

False. A pine cone can only come from a pine tree

Most conifers have “wings” for wind dispersal; what is an advantage of this?

The tree does not have to spend resources on attracting animals

As we know most, but not all, conifers have cones, how are Yew tree seeds dispersed?

By birds, not the wind

Why is it better to call pine nuts “pine seeds”?

Nuts are a type of fruit and only angiosperms produce fruits; pines are gymnosperms

True or False: 99% of all tree species are angiosperms

True

What is the structure of an angiosperm seed (4 things)?

1. Embryo (2N)

2. Endosperm (3N): Provides nutrients for the seed to germinate

3. Cotyledon

4. Seed coat

What are monocots and dicots?

Monocots have one cotyledon and dicots have two cotyledons

Examples of monocots?

Rice, wheat, and palm trees (which are not actually trees because they don’t have a woody stem)

Examples of dicot?

All angiosperm trees are dictos where they store resources in their two cotyledons

Where are nutrients found in an angiosperm seed?

In both the endosperm and cotyledons

What is the #1 method to disperse angiosperm seeds?

Animal transport because it can usually go farther

What are the other methods?

Light hairy seeds blown by the wind, hooks to attach to things, and transport by water

What is seed dormancy?

It is when a seed is dispersed and mature yet does not grow despite favourable conditions

What about embryo dormancy (a type of seed dormancy)?

Requires exposure to low T to get out of dormancy and then heat and moisture to germinate

What is the purpose of embryo dormancy?

So the seed doesn’t grow during winter and die; rather it grows during spring to summer time

What is seed coat dormancy (another type of seed dormancy)?

When a seed coating’s impermeability to water and gasses cause it to remain dormant that can only be broken by physical damge or low T

What is the purpose of seed coat dormancy?

Same as for embryo dormancy