. Nature-study; a manual for teachers and students. Nature study. LESSONS WITH PLANTS 327 simple cases of cross-pollinalion, such as the sweet pea, the morning-glor)', sweet clover, etc. Try tliis exijcriment: Tie over a sweet pea bud or a red clover head a paper or muslin bag. The flower so treated will not form seeds. In many flowers there is provision, however, for the pollen to come in contact with the stigma of the same flower. Self-pol- hnation thus takes place and seeds will form. A better experiment is this: Select some flowers that have pistillate and stami- nate flowers separate, whe
. Nature-study; a manual for teachers and students. Nature study. LESSONS WITH PLANTS 327 simple cases of cross-pollinalion, such as the sweet pea, the morning-glor)', sweet clover, etc. Try tliis exijcriment: Tie over a sweet pea bud or a red clover head a paper or muslin bag. The flower so treated will not form seeds. In many flowers there is provision, however, for the pollen to come in contact with the stigma of the same flower. Self-pol- hnation thus takes place and seeds will form. A better experiment is this: Select some flowers that have pistillate and stami- nate flowers separate, where self-pollination is impossi- ble. The squash, pumpkin or cucumber is very good for this. Cover the pistil- late flower so insects can- not get at the stigmas, and no seeds or fruit wiU form. This will bring out well the importance of the sta- mens and pistil and also of the process of pollination. Re- fer to the subject of cross-pollination as treated under In- sects, page 224. In these grades also a simple study may be made of another method of pollination, namely, by the wind. Get the pen- dulous catkins of cottonwood and butternut, the staminate. Fig. 136. PullinLition in Sweet Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Holtz, Frederick Leopold, 1870-. New York, C. Scribner's Sons
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