. The elements of structural botany [microform] : with special reference to the study of Canadian plants, to which is added a selection of examination papers. Plant anatomy; Botany; Plantes; Botanique. Fig. 117. gymnospermouSi that is, naked-seeded. All the plants previously examined, on the other hand, have their seeds enclosed in ovaries; hence they are all angiospermous. The scales of the cone are to be regarded as open carpellary leaves, and each of them, with its pair of ovules, constitutes a fertile flower. The pollen is carried by the wind directly to the micropyle of the ovule, there b
. The elements of structural botany [microform] : with special reference to the study of Canadian plants, to which is added a selection of examination papers. Plant anatomy; Botany; Plantes; Botanique. Fig. 117. gymnospermouSi that is, naked-seeded. All the plants previously examined, on the other hand, have their seeds enclosed in ovaries; hence they are all angiospermous. The scales of the cone are to be regarded as open carpellary leaves, and each of them, with its pair of ovules, constitutes a fertile flower. The pollen is carried by the wind directly to the micropyle of the ovule, there being no intervening stigma; but, as the quantity of pollen produced is immense, the chances of failure to reach the ovules are very slight. At the time of pollination, the air in a pine forest is full of pollen. The yellow scum often found on water after a summer shower is chiefly Pine pollen. After fertilization the ovules develope into seeds, and the scales of the cone, which are origin- all;' >â rather soft texture, attain a woody couciotency. This process of maturing, how- ever, in the Pine takes considerable time. The cones do not ripen until the autumn of Fig. lis. the second year, after flowering. At this time the scales diverge from the axis, and the seeds are allowed to escape, each of them being now furnished with a wing, which enables the wind more readily to waft it away. The number of cotyledons in the embryo is variable, but is always more than two; sometimes there are as manv as twelve. The wood of the Gymnosperms is essentially like that of the Dicotyledons, and the stem thickens in the same way. Certain differencea Fig. 119. will be noticed in another place. Fig. 117.âSingle scale of Pine cone with its bract. (Wood and Steele.) Fig. 118.âInner side of the scale, showing the two nalied ovules. (Wood Fig. 119.âStaminAtA catkins of Ground Hemlook. (and Steele.). Please note that these images are extracted from scanned page images that may have been digitall
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, booksubjectpl
