. Elementary botany . Botany. CONIFERS 49 branches, and occupy positions taken by dwarf-shoots on vegetative branches. Above the spike-Uke inflorescence of staminate flowers, a 66 65 few foliaged dwarf- branches are seen. On older shoots, two to three years old, the spurs {n) or scars of the fallen stamin- ate flowers denote the points at which the latter were at- tached. Thus a car- pellary flower takes the place of a lateral long-shoot; whereas a staminate flower replaces a vegetative dwarf-shoot. Pollination and its consequences.— The flowers are pol- linated bytheagency of the wind. When r
. Elementary botany . Botany. CONIFERS 49 branches, and occupy positions taken by dwarf-shoots on vegetative branches. Above the spike-Uke inflorescence of staminate flowers, a 66 65 few foliaged dwarf- branches are seen. On older shoots, two to three years old, the spurs {n) or scars of the fallen stamin- ate flowers denote the points at which the latter were at- tached. Thus a car- pellary flower takes the place of a lateral long-shoot; whereas a staminate flower replaces a vegetative dwarf-shoot. Pollination and its consequences.— The flowers are pol- linated bytheagency of the wind. When ready for pollination in May, the carpel- lary cone stands erect (c, cP). Its axis (receptacle) elongates, and thus causes the carpels to separate to a slight extent. The pollen-grains which are blown against the cones naturally reach the crevices between the carpels. They then roll down the prominent rib of the placental scales, and thus meet with the integuments of the ovules. The integuments curl up slightly, and carry the pollen towards the top of the nucellus —that is, towards the bottom of the micropyle-passage. In the Pine, the pollen-grain itself reaches the micropyle, whereas. Fig. 67 68 -Vertical section of carpellary flower of Scotch Pine. Fig. 66.—Carpel of ditto. Fig. 67.—Carpel of fruit of ditto, with two' seeds {s) having wings (h/) in contact with them. Fig. 68.'—Vertical section of seed of ditto :_ tf=endo- sperm; C£7^= cotyledons ; ^=:plumule; r=radicle; ?«= 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 Groom, Percy, 1865-1931. London : G. Bell
Size: 1306px × 1913px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1898
