Text-book of botany, morphological and physiological . l remains,the cork-cambium is formed in the cor-tical parenchyma, and at first presentsthe appearance as if a second epidermiswere formed with cells greatly thickenedon the outside. As the epidermis is at first replaced bythe periderm, so the periderm is afterwardsreplaced by the formation of bark when theincrease in thickness continues long and vi-gorous. In larger woody plants, as oaks andpoplars,the surface of one-year-old boughs iscovered with epidermis, that of several-year-old boughs with periderm, that of the olderbranches and of th
Text-book of botany, morphological and physiological . l remains,the cork-cambium is formed in the cor-tical parenchyma, and at first presentsthe appearance as if a second epidermiswere formed with cells greatly thickenedon the outside. As the epidermis is at first replaced bythe periderm, so the periderm is afterwardsreplaced by the formation of bark when theincrease in thickness continues long and vi-gorous. In larger woody plants, as oaks andpoplars,the surface of one-year-old boughs iscovered with epidermis, that of several-year-old boughs with periderm, that of the olderbranches and of the stem with bark^ Theformation of bark depends on the repeatedproduction of new lamellae of phellogen inthe succulent cortical tissues of Conifers andDicotyledons which continue to grow fromwithin outwards. Layers of cells whichcan extend themselves through the mostdifferent tissues of the cortex, becomechanged into cork-cambium, which be-comes torpid after the production ofthicker or thinner lamellae of cork, /. cut out, so to speak, from the. Fu;. 79.—roriuation of cork in a one-year old branch oRibes nigrinn; part of a transverse section; e epidermis, hhair, b bast-cells, pr cortical parenchyma distorted by the in-crease in thickness of the branch; A the total product of thephellogen f; /t the cork-cells arranged radially in rows formedfrom c in centrifugal order, pd phelloderm (parenchyma con-taining chlorophyll formed from c in centripetal direction)(Xsso). /. e. ceases to be active. These lamellae ofcortex, scaly or annular pieces of the surface ;everything which lies outside them becomes dried up; and since this process is con-stantly repeated on the outside of the stem, and the new lamellae of cork continu-ally intrench further on the growing cortical tissue, a layer, constantly increasing inthickness, of dried up masses of tissue becomes separated from the living part of thecortex, and this is the Bark. The process is very clear in the bark of the oriental pla
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
