. Plant life and plant uses; an elementary textbook, a foundation for the study of agriculture, domestic science or college botany. Botany. flowers and Fig. 129. — Pollen grain of pine showing the wings which aid in its journey through the air. of many trees; poplars, oaks, birches, and pines are ex- amples. In most wind-pollinated trees the flowers appear before the leaves, another feature which is evidently favorable to the process. Many monoclinous nearly all diclinous ones are wind-pol- linated ; insect-pol- lination, with a few exceptions, is confined to monoclinous flowers. (Why is monoc
. Plant life and plant uses; an elementary textbook, a foundation for the study of agriculture, domestic science or college botany. Botany. flowers and Fig. 129. — Pollen grain of pine showing the wings which aid in its journey through the air. of many trees; poplars, oaks, birches, and pines are ex- amples. In most wind-pollinated trees the flowers appear before the leaves, another feature which is evidently favorable to the process. Many monoclinous nearly all diclinous ones are wind-pol- linated ; insect-pol- lination, with a few exceptions, is confined to monoclinous flowers. (Why is monocliny more favor- able to insect-pollination than dicliny is ?) As you have noted, close-pollination is a physical impossibility for diclinous flowers; for them only geitonogamy and xenogamy are possible. Thus it is inter- esting to note that many wind-pollinated plants have structures and habits which favor xenogamy and make geitonogamy difficult or impossible. Poplar, ash, box elder, juniper, and meadow rue insure xenogamy by being dioecious, while in the hazel (see Figure 104) and in the pine xenogamy is favored by the fact that the pistillate flowers are borne higher up than the staminate ones. Also in monoecious forms, the pistillate flowers usually ripen before the staminate ones of the same individual. In alders and in cat-tails this difference in the time of flower ripening may amount to several Fig. 130. — Part of a panicle of a meadow grass. Two of the lower flowers have opened. Note that each of these has two plumose stig- mas and three sta- mens whose long and slender fila- ments expose the anthers to the 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 Coulter, John G. (John Gaylord), b. 1876. New York, American Book Co
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1913
