. The natural history of plants. Botany. 'Sis 147. Triflorous male scale (f). Fig. 148. Lorta;. sect, of triflorous male scale. Pig. 149. Male flower. Fig. Fruit (-f). Betula alia. papillae. In each of the ovarian cells (which are, like the styles, anterior and posterior), there is, in the internal angle, a placenta supporting a single^ descending anatropous ovule, with the micropyle directed upwards and outwards.* The fruit, flat and edged with two mem- branous wings perceptible on the ovary and rendering it samaroid, is dry ^ and indehiscent, interlocular and monosper- raous by abortio
. The natural history of plants. Botany. 'Sis 147. Triflorous male scale (f). Fig. 148. Lorta;. sect, of triflorous male scale. Pig. 149. Male flower. Fig. Fruit (-f). Betula alia. papillae. In each of the ovarian cells (which are, like the styles, anterior and posterior), there is, in the internal angle, a placenta supporting a single^ descending anatropous ovule, with the micropyle directed upwards and outwards.* The fruit, flat and edged with two mem- branous wings perceptible on the ovary and rendering it samaroid, is dry ^ and indehiscent, interlocular and monosper- raous by abortion of one of its seeds,'' whilst the other is fertile and encloses under its coats a fleshy embryo, straight and destitute of albumen, with superior radicle and cotyledons fleshy and nearly flat.âThe Birches are trees and shrubs growing in the cold and temperate regions of both worlds,'^ Fig. 152. Male catkins. Fig. 155. Female catkin. They ' Admitting four stamens they have, in con- sequence, been described as diadelphoua. " In reaUty unilocular and possessing pri- marily two parietal placentae which unite near the centre of the cavity, one of them generally becoming more or less completely abortive. 3 Very rarely two ovules correspond to one cell, only one of which is perfectly developed. â ⢠It has a simple coat. ' At the centre, the ovary is traversed by a vertical fascicle, itself surrounded by a disunited nellular tissue, forming part of the partition, â very thick below, of the pericarp. ^ Frequently there are two, but in that case one or the other is often sterile. J As are the JBetiila in general, except one species of Alnus which inhabits southern Africa. (Rno.) Those which, in much smaller number, are observed in tropical Asia and America, grow on high 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 rese
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1871
