Exercise 17 - Plant Phylogeny

The anatomy and life cycles of liverworts, mosses, ferns, conifers, and flowering plants are studied to determine how they are adapted to a terrestrial environment. Life-cycle stages in alternation of generations are discussed.

EQUIPMENT	AMOUNT (Class of 24 with 8 groups)
Compound microscope	1/student
Dissecting microscope	1/student

MATERIALS

SOLUTIONS

Bold's mineral medium in 0.7% agar for ferns and mosses (CBS#15-6788)
Phloroglucinol stain (CBS#88-1321)*

PREPARATION

Eight Weeks before Lab

An order should be placed for the phloroglucinol staining solution, fern/moss agar, and any moss or fern that will not be available locally the day of the lab.

Six Weeks before Lab

Starting six weeks before lab and every week thereafter, dust a few fern spores on the surface of Bold's medium in 0.7% agar. Follow directions supplied by CBS with spores. Alternatively, young and developed prothalli can be ordered to arrive in time for the lab.

Week before Lab

Previously ordered material should arrive at this time. Living material can be collected when in season. Mosses can be found in shady damp areas or on protected river banks. Material can be kept in a small culture bowl covered with plastic wrap. Make certain some of the soil is transferred with the specimen.

NOTES

1. To assist the student in organizing the materials presented in the lab class, prepare a station for each plant group. After thorough study, student groups can rotate to the next station.

2. Students may want to collect pine pollen in the spring of the year.

3. A slide show on diversity can be run continuously during the day in a hallway showcase using a rear projection, automatic projector (Caramate). Or, if the library has a media center, a tape-slide show can be on reserve for out-of-class viewing.

4. Wm. C. Brown Publishers offer several plant (and animal) keys in their Pictured Key Nature Series.

ANSWERS TO CRITICAL THINKING QUESTIONS

1. Plants of the divisions Bryophyta, Hepatophyta, and Pteridophyta all require water for fertilization and lack root systems. Also, Bryophytes and Hepatophytes lack vascular tissue. Therefore, these plants are not normally found in desert biomes.

2. Because the precipitation is so high, expect to see all plants requiring water for fertilization such as the divisions Bryophyta, Hepatophyta and Pteridophyta. Evergreen trees of the division Coniferophyta, with their extensive root systems and well developed vascular tissue are the dominant plants. Division Anthophyta is also represented by smaller plants tolerating low light and high moisture levels.

3. Lignified vascular tissue.

SUPPLEMENTAL MATERIALS

Bio Sci II, videodisc--contains many illustrations of plant diversity. Dubuque, IA: Wm. C. Brown Publishers. See appendix.

Conifers: Reproduction and Growth, 21-minute VCR showing reproduction, growth, and structure of pine. Concord, NH: Essayo.

The Evolution of Vascular Plants-Ferns, 17-minute film. Chicago, IL: Encyclopaedia Britannica Educational Comp.

Introduction to the Ferns, slide set. Burlington, NC: REX Educational Resources Company. #M5350

Mosses and Club Mosses, slide set. Rochester, NY: Ward's. #173W0629

Moss Life Cycle, 9-minute audio filmstrip. Burlington, NC: Carolina Biological Supply. #5284-52

Origin of Land Plants: Liverworts and Mosses, film. Chicago, IL: Encyclopaedia Britannica Educational.

Pine Life Cycle, 9-minute audio filmstrip. Burlington, NC: Carolina Biological Supply. #52-8672