Angiosperms and Gymnosperms
PRACTICAL 6
Seed Plants (Gymnosperms and Angiosperms)
OBJECTIVES: 1. To describe the features of seed plant life cycle and the concept of the dominant generation. 2. To describe the life histories and related reproductive structures of gymnosperms and angiosperms. 3. To summarize the features that distinguish gymnosperms and angiosperms. 4. To discuss the advantages of seed plants to dominate land and their evolutionary adaptations on land.
EXPERIMENT 1: Gymnosperms
INTRODUCTION:
Gymnosperms (720 species in 65 genera) are ancient seed plants that include ginkgos (Division Ginkgophyta), cycads (Division Cycadophyta), conifers (Division Coniferophyta), and gnetophytes (Division Gnetophyta). The term gymnosperm derives from the Greek wood roots gymnos, meaning “naked”, and sperma, meaning “seed”. They are naked-seeded plants meaning that the ovule, which becomes a seed, is exposed on the sporophyte at pollination. Mature seed are not enclosed in a fruit as are those of flowering plants. Gymnosperms are best known for their characteristic cones, called strobili. These strobili display sporangia and their subsequently developing ovules and pollens. Gymnosperms do not require water for sperm to swim to reach the egg as do seedless plants. Instead, immense amount of windblown pollen are produced.
Most gymnosperm cones, including the familiar pine cone, are complex whorls of leaflike, woody scales around a central axis. The smallest cones include those of the junipers (Juniperus) which have flesh scales fused into a structure resembling a berry. The larger cones may weigh 45 kg and are produced by cycads. In most gymnosperm species, the female megastrobilus is larger and distinctive from the male microstrobilus.
MATERIALS: 1. Living or preserved specimens of * Ginkgo (Ginkgo biloba) * Cycad (Cycad sp.) * Pine (Pinus sp.) 2. Prepared slide of gymnosperms 3. Compound microscope 4. Dissecting microscope 5. Slide and coverslip 6.
Seed Plants (Gymnosperms and Angiosperms)
OBJECTIVES: 1. To describe the features of seed plant life cycle and the concept of the dominant generation. 2. To describe the life histories and related reproductive structures of gymnosperms and angiosperms. 3. To summarize the features that distinguish gymnosperms and angiosperms. 4. To discuss the advantages of seed plants to dominate land and their evolutionary adaptations on land.
EXPERIMENT 1: Gymnosperms
INTRODUCTION:
Gymnosperms (720 species in 65 genera) are ancient seed plants that include ginkgos (Division Ginkgophyta), cycads (Division Cycadophyta), conifers (Division Coniferophyta), and gnetophytes (Division Gnetophyta). The term gymnosperm derives from the Greek wood roots gymnos, meaning “naked”, and sperma, meaning “seed”. They are naked-seeded plants meaning that the ovule, which becomes a seed, is exposed on the sporophyte at pollination. Mature seed are not enclosed in a fruit as are those of flowering plants. Gymnosperms are best known for their characteristic cones, called strobili. These strobili display sporangia and their subsequently developing ovules and pollens. Gymnosperms do not require water for sperm to swim to reach the egg as do seedless plants. Instead, immense amount of windblown pollen are produced.
Most gymnosperm cones, including the familiar pine cone, are complex whorls of leaflike, woody scales around a central axis. The smallest cones include those of the junipers (Juniperus) which have flesh scales fused into a structure resembling a berry. The larger cones may weigh 45 kg and are produced by cycads. In most gymnosperm species, the female megastrobilus is larger and distinctive from the male microstrobilus.
MATERIALS: 1. Living or preserved specimens of * Ginkgo (Ginkgo biloba) * Cycad (Cycad sp.) * Pine (Pinus sp.) 2. Prepared slide of gymnosperms 3. Compound microscope 4. Dissecting microscope 5. Slide and coverslip 6.
References: 1. http://faculty.unlv.edu/landau/gymnosperms.htm 2. http://www.kew.org/plants/conifers/uses.html 3. http://edhelper.com/ReadingComprehension_37_251.html