. The natural history of plants. Botany. 226 NATURAL HISTORY OF PLANTS. anther, dehiscing by a longitudinal cleft.^ The female flovers are disposed in a very short bud-like catkin (£lg. 172), with alternate and imbricate bracts, few in number. In the axil of each of these are found the flowers, arranged in pairs and surrounded each by an involucre covered with hairs, coryius Aveiima. formed by the lateral second- ary bract, here more or less deeply cut and finally sur- rounding the floral receptacle. The latter has the form of a sac with narrow opening, en- closing in its cavity the ad- nate
. The natural history of plants. Botany. 226 NATURAL HISTORY OF PLANTS. anther, dehiscing by a longitudinal cleft.^ The female flovers are disposed in a very short bud-like catkin (£lg. 172), with alternate and imbricate bracts, few in number. In the axil of each of these are found the flowers, arranged in pairs and surrounded each by an involucre covered with hairs, coryius Aveiima. formed by the lateral second- ary bract, here more or less deeply cut and finally sur- rounding the floral receptacle. The latter has the form of a sac with narrow opening, en- closing in its cavity the ad- nate ovary surmounted by a small annular calyx, very short, epigynous and sur- rounding the base of a style soon divided into two large sub- ulate stigmatiferous branches, coloured red.^ In the inferior ovary,' there were originally two parietal placentae uniting along the axis of the cavity to form two cells, each of which might bear two ovules; but ordinarily in the adult flower, each cell contains only one descending anatropous ovule,* with micropyle directed upwards and outwards.^ The fruit, around which the secondary bract, forming the involucre, has taken the form of a long green sac, is an achene the pericarp of which, dry and indehiscent, unilocular and monospermous,® is formed partly of the hardened walls of the receptacular pouch ; it is crowned with the scars of the style and calyx. The descending seed, surrounded by a soft disconnected''' tissue, encloses under its coats a large fleshy. Fig. 172. Female in- florescence (-f-). Fig. 173. Young fruit, long. sect. ff-). ' According to H. Mohl. the pollen is similar to that of the BetuUis. Its spherical granules open hy three pores (Hass. Ann. and Mag. Nat. mat. ix. 556). , ^ It is the only portion of the female flower which exists at the period of fioration. ' Not formed till much later, near the middle of spring. â ⢠Strictly there may he four ovules, two on each placenta, two of which are sooner or later arrested
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1871
