. A textbook of botany for colleges and universities ... Botany. In many species with wind pollination, and especially in those without catkins that move readily in the wind, the stamens have long and slender filaments, which so expose the anthers that they are shaken in the gentlest air movements (as in the grasses and the box elder, figs. 1159, 1162, 1163). In the nettles the pollen is discharged into the air by a sudden move- ment of the filaments. In many plants pollen that falls in quiet weather accumulates in pockets of one sort or another, whence it is scattered readily by the first bre
. A textbook of botany for colleges and universities ... Botany. In many species with wind pollination, and especially in those without catkins that move readily in the wind, the stamens have long and slender filaments, which so expose the anthers that they are shaken in the gentlest air movements (as in the grasses and the box elder, figs. 1159, 1162, 1163). In the nettles the pollen is discharged into the air by a sudden move- ment of the filaments. In many plants pollen that falls in quiet weather accumulates in pockets of one sort or another, whence it is scattered readily by the first breeze. In most wind- pollinated species (not, how- ever, in most grasses and sedges) the pollen is produced in great abundance; this is a matter of much advantage in view of the great waste. The abundance of pine pollen re- sults sometimes in the so-called sulfur showers, and the abun- dance of ragweed pollen in the air is thought to be a factor in causing hay fever. Wind-scattered pollen com- monly is smooth, light, and dry, and hence easily blown about (fig. 1161), and in the pines, dispersal is facilitated further by the presence of a wing on each side of the grain (fig. 1164). In wind-pollinated species the pollen grains are not easily wetted, thus further resembling the spores of fungi and ferns; this is highly advantageous, since moistening might prevent wind Fig. 1162. — A panicle branch of the meadow fescue {Fcs- tuca elatior), a plant moQoclinous wind-pollinated flow- ers ; note the unopened spikelets above with their imbricated scales; below to the right is a spikelet in which two of the lower flowers have opened, each disclosing two plumose stigmas and three stamens whose long and slender fila- ments expose the an- thers to the wind. Fig. 1163. — The upper part of a plan- tain spike (Plantago), illustrating protogyny in monoclinous wind- pollinated flowers; note that the conspic- uous plumose stigmas (g) appear before the stamens are evident; in the older flo
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1910
