Lab 5: Plant Diversity I

2n

Diploid. 2n. Having 2 sets of homologous chromosomes. Humans somatic cells are 2n and have 23 pairs, or 46 chromosomes.

Why are land plants so successful?

They evolved key diagnostic traits that provide increasing support of the embryo and allowed survival on land.

Seedless vascular plant; lycophyte, clubmoss (genus Lycopodium

club moss (genus Lycopodium)

phloem

conducts most of the sugars, amino acids, and other products through the plant.

xylem

conducts most of water and dissolved nutrients like minerals up from the roots

gemmae cups

cup-like structure growing on the thalli of liverworts

Seedless vascular plant; monilophyte, horsetail (genus Equisetum)

horsetail

True Ferns

true fern

cuticle

waxy covering that keeps cells from losing water

What seedless vascular plants can you see on campus?

whisk ferns (genus Psilotum) and true ferns.

What do the sperm and egg form when they combine?

zygote

thallus

stem-like and leaf-like, root-like plant body in the nonvascular plants (bryophytes)

vascular tissue

transport fluids, the xylem and phloem.

Is the zygote 1n or 2n?

2n. The sperm and egg are each 1n and combine to form the 2n zygote.

What is a true moss?

A land plant that is also in the clade of bryophytes. Sphagnum moss is a true moss because it is a bryophyte. Club mosses and spike mosses are seedless vascular plants and are not true mosses. Ball mosses are angiosperms and are not true mosses.

alternation of generations

A life cycle in with there are distinct multicellular stages. In land plants have a 2n multicellular sporophyte that produces spores and a 1n multicellular gametophyte that produces gametes.

What are the five evolutionary derived key traits for survival on land? These are synapomorphies.

Alternation of generations, multicellular embryos, sporangia produce walled spores, gametangia produce gametes, apical meristems allow growth.

What are the vascular plants with seeds and flowers?

Angiosperms (flowering plants)

Which group of plants have flagellated sperm that must swim to the eggs, requiring a water environment?

Bryophytes have flagelatted sperm and are dependent on water. Marchantia (liverwort), true mosses, hornworts.

Which group of land plants does not have vascular tissue?

Bryophytes. Represented by liverworts (genus Marchantia), true mosses and hornworts.

autotrophic

Can convert energy from non-living forms into biologically useful energy from light (photosynthesis) or inorganic chemicals (chemosynthesis).

mitosis

Cell division in which both daughter cells have the same number and kind of chromosomes as the parent cell. (Most cellular division in growth)

meiosis

Cell division in which the daughter cells have half the number of chromosomes as the parent cell.

epiphytic

Epiphytes use other plants as a substrate but they do not harm them. Epiphytes are not parasites.

What is the genus of the horsetail, and how is it descriptive?

Equisetum. Equis refers to horse, and the strobilus looks like a horse's tail.

What key character evolved on the lineage to the angiosperms?

Flowers

Of the four main groups of land plants, which two dominate the current landscape? (bryophytes, seedless vascular plants, gymnosperms, angiosperms)?

Gymnosperms and angiosperms

What are the first vascular plants with seeds (naked seeds)?

Gymnosperms are the conifers, ginkgos, and cycads

gametes

Haploid sex cells that unite to form the zygote.

1n

Haploid. 1n. Having a single set of homologous chromosomes. Human egg and sperm are 1n and have 23 chromosomes.

strobili

Hold the sporangia (spore bearing structures) in the seedless vascular plants (horsetail, club mosses and spike mosses). They are larger and more visible in the horsetail.

Sori - on fronds

Hold the sporangia in the true fern. Sori typically look like black disks on the back of fern leaves (fronds). The spornagia produce spores.

spores definition 1 for plants

In plants, a haploid reproductive cells that can develop into multicellular haploid organisms (the gametophyte).

zone of elongation

In the root tissue, the growth region or zone just behind the dividing meristematic cells, where the cells grow larger and elongate.

zone of maturation

In the root tissue, the region or zone just after the zone of elongation, where the newly elongated cells can differentiate into specialized cells (for example, epidermis, cortex, vascular tissue)

root cap

In the root tissue, the structure made of specialized cells that cover the tip of the root and protect it as it grows through the soil.

What are the four important features of land plants the embryophytes?

Like all protists they are eukaryotes. Like some protists they have chloroplasts, and are multicellular. They are a clade derived from protists (green algae).

What are three non-vascular plant groups?

Liverworts (genus Marchantia), mosses, hornworts

In which group are the female and male gametophytes separate plant structures?

Marchantia which is a liverwort, a bryophyte or non-vascular plant

What bryophytes can you see on campus?

Mosses on trees and around downspouts or wet shaded areas.

sporangia

Multicellular diploid organs that produce spores

gametangia

Multicellular haploid organs that produce gametes.

Are all plants also land plants?

No, the group we call plants all have chloroplasts, while the group we specify as land plants have four additional features and five derived key traits for survival on land.

Can bryophytes grow to be very large?

No, they lack vascular tissue. Because fluids must move from cell to cell by diffusion, they cannot grow large.

Do humans show alternation of generations?

No. Humans and animals have haploid cells, but they never produce a multicellular gametophyte structure. Animals only produce single-celled gametes, not a separate multicellular generation.

Sori closeup of sporangia

Note the closeup of the sporangia. You can see the dark spores in the sporangia.

bryophyte; liverwort. genus Marchantia

Note the thalli (leaf-like) and the archegonia (female gametophytes)

chloroplasts

Organelles that conduct photosynthesis or conversion of light energy to food energy. Allows cells to be autotrophic.

eukaryote (Eukarya)

Organisms in the domain Eukarya; cells with a true nucleus (or "kernal").

rhizoids

Root-like structures in the non-vascular plants (bryophytes). The gametophytes of true ferns are non vascular and also have rhizoids. Note that the sporophytes of true ferns have vascular tissue and have true roots.

What key character evolved on the lineage to the gymnosperms and angiosperms?

Seeds. Both have seeds, but the seeds are naked in gymnosperms, and protected within angiosperms.

Ranunculus root - note the vascular tissue

Similar but not identical to the slide you saw in class. Note the xylem and phloem in the central core of the root. The xylem forms a cross and surrounded by phloem.

corn prop root - note the vascular tissue

Similar but not identical to the slide you saw in class. Note the xylem and phloem in the internal ring of the root. The xylem makes up the larger circles in the internal ring and is surrounded by the smaller phloem cells. The pith is centrally located in the root.

What are the seedless vascular plants?

There are two groups 1) the lycophytes: club "mosses", spike "mosses", and quillworts (no specimen), and 2) the monilophytes: whisk "ferns", horsetails, and true ferns

What are the bryophytes?

These are the nonvascular land plants; liverworts (genus Marchantia), mosses, hornworts

What does the word moss refer to?

Soft, small, and green type of plant. Club mosses and spike mosses are seedless vascular plants that are soft, green but are not true mosses in the Clade Bryophyta. Ball mosses are in the clade of angiosperms because they have flowers.

What are gemmae cups?

Structures that grow on the upper side of the leaf-like thalli of Marchantia (bryophyte liverwort). Gemmae give rise to the antheridia and archaegonia structures.

Name two epiphytes

The club moss Lycopodium, and many of the ferns you saw outdoors that grow on trees such as the resurrection fern (pointed out on the walk and in the photo).

What structure produces eggs?

The female gametangia is the archegonia

archegonia

The female gametangia that produce eggs

gametophyte

The generation that produces the gametes. 1n.

sporophyte

The generation that produces the spores. 2n

embryophytes (Embryophyta)

The land plants. The term refers to the multicellular embryos that are dependent on the female parent. The most successful groups provide the greatest support for the embryo.

frond

The leaflike part of a fern.

What structure produces sperm?

The male gametangia is the antheridia

antheridia

The male gametangia that produce sperm

leaf anatomy

The model in class showed the top layer of cuticle, then epidermis, palisade parynchyma cells, spongy parenchyma cells with the xylem and phloem, then lower epidermis and lower cuticle. Note the stomata and guard cells in the lower epidermis.

cellulose

The primary component of cell walls of green plants.

parasitic

The process when one organism (the parasite) lives on or in another organism (the host) and harms the host.

How is the female organism defined in biology?

The sex that produces the large gamete

sporangia

The structure that produces spores

meristematic tissue

Tissue in which there is active cell division and in which tissue that can differentiate into other tissues.

roots, true roots.

True roots have vascular tissue and anchor plants.

What key character evolved on the lineage to the seedless vascular plants, gymnosperms, and angiosperms?

Vascular tissue. Vascular tissue evolved early in the lineage shared by the three groups.

Seedless vascular plant; monilophyte, whisk fern (genus Psilotum)

Whisk fern - you can see them on campus in the landscaped beds, especially among the rocks.

Are humans related to plants?

Yes, all life has arisen from one or a few forms and all are related to one another, however distantly. Both plants and animals belong to the same domain, Eukarya and are more closely related to each other than they are to the bacteria or archaea (the other two domains of life).

Are plants alive?

Yes. Plants are alive. It is a common misconception that living things must move. Although plants do move (some track the sun, some have motile sperm) movement is not a requirement for life.

fragmentation

a kind of asexual reproduction where a portion of the plant can break off and produce a new plant. For example, the thalli of Marchantia can propagate by asexual reproduction.

spores definition 2 - more general.

a reproductive cell capable of developing into a new individual without fusion with another reproductive cell. Spores thus differ from gametes, which are reproductive cells that must fuse in pairs in order to give rise to a new individual. May be able to withstand dry environments.

protected spores (protected with tough cell walls).

allow for survival for many years in times of drought, can travel far by wind or animals such as insects.

Are land plants autotrophic or heterotrophic?

autotrophic

What are the four main groups of land plants?

bryophytes, seedless vascular plants, gymnosperms, angiosperms

synapomorphy

characteristics present in an ancestral species & shared by its evolutionary descendants. Same as shared derived characters.

What structure are gametes produced in?

gametangia in the gametophyte generation

Which generation is dominant in the bryophytes?

gametophyte is dominant in the bryophytes (liverworts, mosses)

What group did the land plants evolve from?

green algae (a protist)

mega

means large, often referring to female structures (megaspores, megasporangium, megagametophyte)

micro

means small, often referring to male structures (microspores, microsporangium, microgametophyte)

What are some vegetative and reproductive structures that are adaptations to dry land?

meristematic tissue, thallus and rhizoids, stomata, cuticles, vascular tissue, stiff cell walls, roots, leaves, stems, protected spores, tissues to support the embryo.

Apical meristem (meristematic tissue: corn prop root)

meristematic tissue: corn prop root

embryo

once the zygote cell begins to divide and multiply it becomes the embryo.

stomata

openings that regulate gas exchange and control water loss

heterosporous

produces both megaspores and microspores

homosporous

produces only one kind of spore (mega or microspores)

apical meristems

regions of cell division at the tips of roots and shoots (and sometimes on the sides of shoots that grow branches).

apical meristems (meristematic tissue)

regions of cell division at the tips of roots and shoots (and sometimes on the sides of shoots that grow branches). These can differentiate into multiple tissues.

Seedless vascular plant; lycophyte, spike moss (genus Selaginella)

spike moss (genus Selaginella)

What structure produces spores?

sporangia in the sporophyte generation

Which generation is dominant in all land plants except the bryophytes?

sporophyte

What are the two generations that alternate in plant life cycles?

sporophyte (2n) and gametophyte (1n)