General Botany for Universities and CollegesGinn, 1920 - 459 páginas |
Dentro del libro
Resultados 1-5 de 22
Página 128
... anthers and ovules . As soon as fertilization has taken place the young seeds begin to form endosperm , and this process necessitates a constant supply of soluble sugar and pro- tein . Since osmosis takes place from points of greater ...
... anthers and ovules . As soon as fertilization has taken place the young seeds begin to form endosperm , and this process necessitates a constant supply of soluble sugar and pro- tein . Since osmosis takes place from points of greater ...
Página 164
... anthers , with growth of pollen tube through the style to an ovule While the above changes are going on in the pollen the female gamete , or egg cell , is being formed in the ovule . Sections of young ovules and of mature ovules at the ...
... anthers , with growth of pollen tube through the style to an ovule While the above changes are going on in the pollen the female gamete , or egg cell , is being formed in the ovule . Sections of young ovules and of mature ovules at the ...
Página 167
... anthers of a given flower to the stigma of the same flower . Close - pollination will be interpreted as the transfer of pollen from the anthers of one flower to the stigma of another flower or flowers on the same plant . Close ...
... anthers of a given flower to the stigma of the same flower . Close - pollination will be interpreted as the transfer of pollen from the anthers of one flower to the stigma of another flower or flowers on the same plant . Close ...
Página 169
... Anthers Wing petal Funiculus d Seed Keel petals Stigma b Ovary Embryo Style Pistil с h Cotyledon FIG . 89. Structure of the papilionaceous flower of the pea ( Pisum ) a , flower ; b , irregular petals ; c , stamens and pistil exposed ...
... Anthers Wing petal Funiculus d Seed Keel petals Stigma b Ovary Embryo Style Pistil с h Cotyledon FIG . 89. Structure of the papilionaceous flower of the pea ( Pisum ) a , flower ; b , irregular petals ; c , stamens and pistil exposed ...
Página 170
Hiram Delos Densmore. conjunction with the maturing of the stigma , and the anthers are so placed that the pollen is dusted onto the hairs of the stigmatic surface when the anthers dehisce . Self - pollination is thus in- sured , even ...
Hiram Delos Densmore. conjunction with the maturing of the stigma , and the anthers are so placed that the pollen is dusted onto the hairs of the stigmatic surface when the anthers dehisce . Self - pollination is thus in- sured , even ...
Otras ediciones - Ver todas
General Botany for Universities and Colleges (Classic Reprint) Hiram Delos Densmore Sin vista previa disponible - 2016 |
General Botany for Universities and Colleges Hiram D B 1862 Densmore Sin vista previa disponible - 2016 |
Términos y frases comunes
adapted aërial anthers archegonia asexual bacteria bark bean Botany branches buds cambium carbon dioxide carpels cavity cell division cell wall chromosomes composed cortex cotyledons cross-pollination cylinder cytoplasm dicotyledons digestion ducts elongating embryo epidermis female gamete ferments ferns fertilization filaments flowers forest fruit fungi gametangium gametes gametophyte germination grain growing growth habit habitat herbaceous higher plants hybrid hyphæ illustrated inflorescence layer leaves male gametes mature megasporangium megaspore meristem mesophytic microspores mold mother cell mycelium nucleus organs outer ovary ovule phloëm photosynthesis pine pistil pith plant body plants and animals pollen tube portion produced protoplast receptacle reproduction rhizome root tip season seedling seeds Selaginella sieve tubes species sperms Spirogyra sporangia sporangium spores sporophyte spring spruce stamens starch stem stigma storage strobilus structure sugar surface tion tissues trees vacuole vascular vegetative vegetative reproduction wood rays woody xerophytic xylem yeast young zygote
Pasajes populares
Página 208 - Can it, then, be thought improbable, seeing that variations useful to man have undoubtedly occurred, that other variations useful in some way to each being in the great and complex battle of life, should sometimes occur in the course of thousands of generations...
Página 208 - On the other hand, we may feel sure that any variation in the least degree injurious would be rigidly destroyed. This preservation of favorable individual differences and variations, and the destruction of those which are injurious, I have called Natural Selection, or the Survival of the Fittest...
Página 210 - Darwinian can well agree to the statement, "species are derived from other species by means of sudden small changes which, in some instances, may scarcely be perceptible to the inexperienced...
Página 35 - Considering the several facts given in this chapter, we see that the course followed by a root through the soil is governed by extraordinarily complex and diversified agencies, — by geotropism acting in a different manner on the primary, secondary, and tertiary radicles, — by sensitiveness to contact, different in kind in the apex and in the part immediately above the apex, and apparently by sensitiveness to the varying dampness of different parts of the soil. These several stimuli to movement...
Página 36 - ... from or to the exciting cause. A radicle may be compared with a burrowing animal such as a mole, which wishes to penetrate perpendicularly down into the ground. By continually moving his head from side to side, or circumnutating, he will feel any stone or other obstacle, as well as any difference in the hardness of the soil, and he will turn from that side ; if the earth is damper on one than on the other side, he will turn thitherward as a better hunting-ground. Nevertheless, after each interruption,...
Página 176 - Ipvmaia purpurea in the ten generations; the mean height of the crossed plants being taken as 100. On the right hand, the mean heights of the crossed and self-fertilised plants of all the generations taken together are shown. self-fertilised plants will perhaps be best appreciated by an illustration : If all the men in a country were on an average 6 feet high, and there were some families which had been long and closely interbred, these would be almost dwarfs, their average height during ten generations...