Warmup 9/22/15

Tell me everything you know about moss.

Objective Tonight’s Homework

Categorize the variety of plant life

pp 291: 4pp 298: thought question 1, 3

Notes on Plant Taxonomy

Plants are divided into 9 phyla, but we usually group them into 3 major groups based on how plants transport nutrients and reproduce.

Notes on Plant Taxonomy

Plants are divided into 9 phyla, but we usually group them into 3 major groups based on how plants transport nutrients and reproduce.

- The non-vascular plants:These are all the plants in the phylum Bryophyta. These are mosses and similar plants.

Notes on Plant Taxonomy

Plants are divided into 9 phyla, but we usually group them into 3 major groups based on how plants transport nutrients and reproduce.

- The non-vascular plants:These are all the plants in the phylum Bryophyta. These are mosses and similar plants.

- Vascular plants without seeds:This includes 4 phyla. The best known one is Pterophyta, the ferns.

Notes on Plant Taxonomy

Plants are divided into 9 phyla, but we usually group them into 3 major groups based on how plants transport nutrients and reproduce.

- The non-vascular plants:These are all the plants in the phylum Bryophyta. These are mosses and similar plants.

- Vascular plants without seeds:This includes 4 phyla. The best known one is Pterophyta, the ferns.

- Vascular plants with seeds:We split this group into 2 subgroups:- Non-flowering plants- Flowering plants

Notes on Mosses

Structure

Phylum Bryophyta – mosses – are the only plants without a vascular system. This means these plants can’t transport water or nutrients.

So what does this mean?

Notes on Mosses

Structure

Phylum Bryophyta – mosses – are the only plants without a vascular system. This means these plants can’t transport water or nutrients.

So what does this mean?

- Mosses must be able to absorb water and nutrients into each and every cell.- Mosses can’t grow very large because they can’t grow support structures.

Notes on Mosses

Let’s look at a moss in more detail.

Notes on Mosses

Let’s look at a moss in more detail.

At the base is a tangledmass of rhizoids.

These are not true rootsas they do not absorbnutrients for the rest ofthe plant, but they doprovide an anchoring force.

Notes on Mosses

Let’s look at a moss in more detail.

At the base is a tangledmass of rhizoids.

These are not true rootsas they do not absorbnutrients for the rest ofthe plant, but they doprovide an anchoring force.

Above is a simple leafy shoot. The leaves here are just one cell thick to better absorb nutrients.

Notes on Mosses

There are a few downsides to not having a vascular system.

- Since the leaves are so easy to hydrate, it also means they dry out easily. As such, mosses can only grow in moist, humid areas.

Notes on Mosses

There are a few downsides to not having a vascular system.

- Since the leaves are so easy to hydrate, it also means they dry out easily. As such, mosses can only grow in moist, humid areas.

- Since most mosses can only have leaves one cell thick (and stems not much thicker), these plants can’t grow very tall or very wide.

Notes on Mosses

Reproductive Cycle

Mosses have a complex life cycle that we call “Alternation of Generations”. We use this term because, as we’ll see, the moss goes through two life cycles that have to work together to form a complete loop.

Notes on Mosses

We start with a young gametophyte. This stage looks like what we just discussed.

Notes on Mosses

The next stage a mature gametophyte. We keep calling it this because at this point some of the leaves are storing gametes, or reproductive cells.

Some plantshave maleones, othersfemale.

Notes on Mosses

When conditions are right (flooded), the tips of the male gametes open (called antheridia) and release sperm. These sperm swim through the water to thefemalegametes(calledarchegonia).

Here, the eggis fertilized.

Notes on Mosses

The fertilized egg grows within the archegonium and does not get expelled. From here, we’re dealing with the second stage of the life cycle.

Notes on Mosses

The zygote (which we call the sporophyte because it’s going to make spores), grows on the top of the gametophyte. It will try to live as a saprophyteif possible,but if notit will liveparasiticallyoff thegametophyte

Notes on Mosses

When mature, the sporophyte releases asexual spores through simple meiosis.

Notes on Mosses

As these spores drift through the air, they release a shoot of rhizoid called a protonema. Once the spore lands, this shoot anchors and itbecomesa younggametophyte.

The circleis nowcomplete!

Exit Question

Why is liquid a necessary ingredient for moss to reproduce?

a) Without water, the sperm and egg dry upb) Without water, the sporophyte can’t openc) Without water, the sperm can’t swim to the egg.d) Without water, the rhizoids in the ground detache) All of the abovef) Water isn’t necessary, just helpful.