Exercise B Pollen Morphology
1 Only a limited number of pollen slides arc available commercially from biological supply houses. For the pollen in this exercise, you w ill need to make the slides yourself. The pollen can be collected from the field if you plan ahead, but it may be easier to order the pollen from a lab that prepares extracts for allergy injections. Four of til esc pollen types will also be needed to make slides for lixercisc C. Greer Laboratories. Inc. (P.O. Box 800, Lenoir, N( 28f>45% 828-754-5327) stocks a wide variety of pollen types and charges about S3 to 58 per gram for common pollen types. Other labs around the country also have pollen available. One gram of each pollen type w ill be plcnry.
- Once you obtain the pollen, make permanent pollen slides using a glyccriii-jelly mounting medium containing basic fuchsia or phenosafranin to stain the pollen.
- Glvcerin-jcHy mounting medium contains 20 g of gelatin, 70 ml of water, 60 ml of glycerol, and 2.4 g of phenol. Prepare as follows: Boil distilled water. Measure out 70 ml and pour into a beaker contain ing 20 £ of gelatin. Boil again to dissolve the gelatin. Remove from the heat. Add 60 ml of glycerol and 2.4
g of phenol (use a mask and gloves when handling the phenol). Stir well to mix. Add about 4 mg of basic tuchsin or phenosafranin. (Both dyes stain the cxinc, or outer pollen wall, a reddish-purple color.) Stir well to distribute the stain evenly. Pour the mounting medium into small bottles and refrigerate for storage. The mounting medium solidifies as it cools.
- To prepare slides, place the jar of glycerin-jelly in a water bath at about 50°C or above. This will melt the mounting medium. Put a drop on a slide, quickly stir in a sample of the pollen, and mix well. (Try using a toorhpick to pick up a small sample of the pollen.) Add a coverslip and press down slightly. Some of the mounting medium may ooze out. Alter the mounting medium solidifies, use a razor blade to trim off excess glycerin-jelly that has oozed out and hardened. Many people do not consider glycerin-jelly a permanent mounting medium and suggest sealing die slide with clear nail polish; however, this recipe has produced slides that have lasted over 10 years without sealing. (Note: Use great carc when cleaning the slides. If you rub hard you can disrupt the mounting medium.)
- Juniper us pollen has a thin cxine (outer wall). Often, when mounting the pollen in any type of mounting medium, the intine (inner wall) swells and ruptures through the cxinc. Tell students to ignore any ruptured grains and to look for intact ones.
- Pin us pollen has two large air bladders. Students often think this pollen looks like a Mickey Mouse hat or a toreador's hat. Sometimes air gets trapped in the air bladders, and the bladders look black under the microscope.
- The pollen stain used for making w et mounts by the students contains 16 ml of glycerol, 35 ml of 95% cthanol, 49 ml of distilled water, and 3 mg of basic fuchsin or phenosafranin. Place in dropper bottles. It will last for years.
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