THE PLANT KINGDOM

The Plant Kingdom contains numerous organisms of amazing diversity. They are all eukaryotic, multicellular, autotrophic (photosynthetic) organisms that exhibit the Alternation of Generations (Diplohaplonic) life cycle. Members of the Plant Kingdom possess cell walls composed of cellulose, chlorophyll a and b, and store carbohydrates as starch. The higher plants may be divided into two groups based on water storage: bryophytes or non-vascular plants and the tracheophytes or vascular plants.

This lab will focus on the non-vascular bryophytes and the primitive tracheophytes: whisk ferns, club mosses, horsetails, and ferns. These are called “primitive” because unlike the other vascular plants they do not produce seeds. (Primitive and ancient are not synonymous.) All other tracheophytes produce seeds and are either gymnosperms (naked seed) or angiosperms (covered seed).

PROCEDURE

First, look at the BIG picture. Attached is the Plant Kingdom “map.” Acquaint yourself with the map and the vocabulary (tracheophytes, spermatophyte, gymnosperm, angiosperm, etc.) Please learn to rely on this taxonomic map when assimilating new information about higher plants.

In your pre-lab write up, prepare one page for each of the divisions listed below. Provide particular characteristics of each division on that page. Using a compass or round object, draw circles which will represent the microscopic field in which you will sketch the plant slides that you examine. The number of slides varies for each group. Refer to your Atlas, Chapter 6, pages 57 – 73 for assistance in recognizing what you will see microscopically and for labeling.

þ Some of these slides will appear on your practical laboratory examination at the end of the semester. Plan now for some personal review time in the laboratory over the next several weeks to prepare. Keep up with this material as we go along. All these plants can start “growing” together after a while.

Division Bryophyta (mosses, liverworts, hornworts)

These are very ancient land plants. They are the only group of land plants in which the gametophyte plant is dominant and the sporophyte generation is dependent (parasitic) on the gametophyte for nourishment. The gametophyte lacks vascular tissue so these plants are limited in size and in habitat. Where are mosses traditionally found?

QStudy carefully the lifecycle of a typical moss. Draw and label the cycle in your lab report and describe the process in terms of the diplohaplontic life cycle.

Mosses: Division Bryophyta, Class Musci

1. Moss Protonema

· Sketch and label chloroplast

· Are the cells of the protonema haploid or diploid? Explain.

2. Moss Antheridium

· Sketch and label the antheridium; paraphyses

3. Moss Archegonium

· Sketch and label the archegonium and paraphyses

4. Moss Capsule

· Sketch and label capsule, operculum, columella, spores

Liverworts: Division Bryophyta, Class Hepaticae

5. Marchantia

· Label antheridium and archegonium

Division Pterophyta (ferns)

These organisms produce the familiar green frond that are recognized as “ferns.” They produce underground stems called rhizoids, from which fronds emerge as “fiddleheads”. The sporophyte is what we recognize as a fern. The gametophyte is a very small structure possessing the antheridium and archegonium. Flagellated sperm are produced and which are dependent on moist environments for fertilization of the egg in the archegonium some (small) distance away.

Q Carefully study the life cycle of the fern. Draw and label the life cycle of a typical fern in your lab manual. Describe the process in terms of the Alternation of Generations Life cycle. Compare and contrast the life cycle of the fern with the life cycle of a moss.

Prepared Slides:

1. Fern Prothallium

· Sketch and label the antheridium, archegonium, rhizoids (Figure 6.51)

2. Fern Sporangium

· Sketch and label the spores and annulus(Figure 6.54)

3. Observe the plastomounts and herbarium specimens provided

· Be prepared to identify these as to kingdom, division, and in cases where a particular genus has been given, genus.

$ Practice looking for similarities shared by members of a division.

Division Psilophyta (whisk ferns)

These wispy plants have dichotomously branching stems with spherical sporangia (spore containers) on their tips. Bundles of these where ties together and used as “whisk brooms”, hence the name whisk ferns.

1. Psilotom

2. Observe herbarium specimens

Division Lycophyta (club mosses)

The ancestors of modern day club mosses formed the great coal swamps some 300 million years ago. These and all other land plants have a dominant sporophyte generation with true roots, stems and leaves having a vascular system with xylem and phloem.

1. Lycopodium

· the herbarium specimen show sporophylls (leaves with sporangia attached)

2. Selaginella

3. Observe herbarium specimens

Division Sphenophyta (horsetails)

These organisms are also ancestors of the plants which left us the rich coal deposits. They have hollow and jointed stems. The tiny leaves are “whorled” around the joints of the stems. They possess terminal structures, strobili, on which are clustered the sporangia.

1. Equisetum

· horsetail

2. Observe herbarium specimens