Warmup 9/22/15 Tell me everything you know about moss. Objective Tonight’s Homework Categorize the variety of plant life pp 291: 4 pp 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 tangled mass of rhizoids. These are not true roots as they do not absorb nutrients for the rest of the plant, but they do provide an anchoring force.

Notes on Mosses Let’s look at a moss in more detail. At the base is a tangled mass of rhizoids. These are not true roots as they do not absorb nutrients for the rest of the plant, but they do provide 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 plants have male ones, others female.

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 the female gametes (called archegonia). Here, the egg is 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 saprophyte if possible, but if not it will live parasitically off the gametophyte

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 it becomes a young gametophyte. The circle is now complete!

Exit Question Why is liquid a necessary ingredient for moss to reproduce? a) Without water, the sperm and egg dry up b) Without water, the sporophyte can’t open c) Without water, the sperm can’t swim to the egg. d) Without water, the rhizoids in the ground detach e) All of the above f) Water isn’t necessary, just helpful.