Exercise 24 - Reproduction and Development in Flowering Plants

STUDENT OBJECTIVE

Students learn the processes of gamete formation in flowering plants and study plant development. Sexual and asexual reproduction are compared and flower diversity is illustrated. Anatomy of seeds and fruits are examined.

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


MATERIALS

Razor blades 1/student
Dissecting needles 2/student
Microscope slides and coverslips 1 box/lab
Lens paper 8/lab
Living plants
  Lima beans, soaked 1/student
  Corn kernels, soaked 1/student
  Vinca flowers 1/student
  Various monopistillate flowers for dissection 1/student
  Six dicot flowers varying in completeness, some imperfect 2 sets/lab
  Apples, tomatoes, peaches, cucumbers, and other fruits Demonstration
  Grasses with root Demonstration
  Garlic plant with root Demonstration
  Strawberry plants with stolons Demonstration
  Iris plant with root Demonstration
  Germinating dicot and monocot seeds 1/student
  Tulip or other large monocot 1/lab
  Seeds (beans, spinach, turnip, etc.) Demonstration
Preserved plants
  Oat flowers (CBS#PB1210)* 1/student
  Examples of corn staminate and pistillate flowers (CBS#PB960)* Demonstration
  Preserved lily flower bud (CBS#PB 1236)* 1/student
Prepared slides (can be shared to reduce costs)
  Capsella (Shepherd's purse) embryo, longitudinal section
     (CBS#B 716A and B 718)* 1/student
  Lily anther, cross section (CBS#B 685)* 1/student
  Lily ovulary, cross section (CBS#B700, B701, B709, and B710A)* 1/student
  Lily pollen tubes, longitudinal section (CBS#B691)* 1/student

SOLUTIONS

10% sucrose

PREPARATION

About Three Weeks before Lab

Locate a local source of fresh flowers for lab (greenhouses or florists). Order flowers to arrive in midbloom to full bloom.

Week before Lab

  1. About three days before lab, soak lima beans and corn kernels so that students can dissect.

  2. Plant seeds in tray of soil. Cover with vermiculite and keep moist. Vary time of planting so that seedlings at various stages of development are available for lab.

  3. 10% sucrose preparation:

    10 g sucrose/90 ml water

    Store in dropper bottles.

ANSWERS TO CRITICAL THINKING QUESTIONS

  1. Tomato, cucumber, squash, peas, beans, egg plant, and peppers. All of these vegetables have flesh that is derived from the ovarian wall and they contain seeds.

  2. Pollen from different species of flowers is often shed at different times of the year. If pollen arrives before the stigma is receptive it will not fertilize the eggs of a species. Sugary secretion and other chemical stimulants produced by one species may not trigger pollen tube formation in a second species. If the pollen tube forms and starts migrating through the tissues of the stigma and style, chemical signals of one species may not guide the pollen tube of a second species in an appropriate manner so that the tube does not find the micropyle. In some species the pollen tube that forms may not be long enough or too long to find its way to the micropyle.

SUPPLEMENTAL MATERIALS

Bio Sci II, videodisc contains many images applicable to this exercise. Dubuque, IA: Wm. C. Brown Publishers. See appendix.

Angiosperms--The Flowering Plant, 20-minute film. Chicago, IL: Encyclopaedia Britannica Educational Corp.

Chemotropism, a 7-minute VCR showing ovule attraction of growing pollen tube in vitro. Concord, NH: Essayo.

Corn, Zea mays, a 27-minute VCR showing fertilization in corn. Concord, NH: Essayo.

Double Fertilization and Embryo Development in Flowering Plants, 31-minute video filmstrip. Burlington, NC: Carolina Biological Supply.

Introduction to Gametogenesis, audio filmstrip. Rochester, NY: Ward's. #78W0210

Lily, Lilium longiflorum, a 22-minute VCR showing meiosis and embryo development. Concord, NH: Essayo.

Pollen Tube Growth, film loop. Rochester, NY: Ward's. #168W5122

Seed Germination, Root Formation, and Seedling Development, a 25-minute VCR showing several species. Concord, NH: Essayo.

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