. Elements of plant anatomy;. Botany -- Anatomy. 82 ELEMENTS OF PLANT ANATOMY. families. Tlie single cell lias one outer surface wall and either two or three inner walls surrounded by the cells of the growing end. Where there are two inner walls, the new walls arise alternately, first on one, and then on the other side of the cell and parallel with the existing inner walls. Where the outer or surface wall is three-sided, the other three walls are enclosed in the Fig. 39. growing end, making a triangular pyramid, and the new partition walls arise so that each is parallel with the third before t
. Elements of plant anatomy;. Botany -- Anatomy. 82 ELEMENTS OF PLANT ANATOMY. families. Tlie single cell lias one outer surface wall and either two or three inner walls surrounded by the cells of the growing end. Where there are two inner walls, the new walls arise alternately, first on one, and then on the other side of the cell and parallel with the existing inner walls. Where the outer or surface wall is three-sided, the other three walls are enclosed in the Fig. 39. growing end, making a triangular pyramid, and the new partition walls arise so that each is parallel with the third before the last, therefore at an angle of 120° with the last wall. From the unequal rapidity of growth of the segments, the meristem cell or cells lie in a sinus at the growing end of the thalloid forms. The normal branching takes place in this sinus, the last segment cut off becomes a new apical cell and by its rapid growth pushes aside the original one and thus a dichotomous divi- sion is brought about. The simplest forms show no other differentiation of tissues than the possession of a midrib of several layers, while the thallus proper is composed of only one layer of cells. In the higher forms, there is an epidermis with organs corresponding to the stomata of higher plants. The thallus of the higher forms consists of several lay- ers of cells composing different sets of tissues, which resemble those of similar functign in higher plants. There is a distinct epidermis which covers both sides of the thallus, but its struc- ture on the upper, is unlike that on the under side. Numerous epidermal qcIIs of the under surface are extended into rhizoids, which fasten the plant to the soil and furnish it, in part, with food. On the upper surface the connection between the epider- mis and the tissues below is interrupted in such a manner as to leave regular air spaces between them. A single stoma opens into each of these spaces, which are partly filled with assimi-. Please note that these ima
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotanya, bookyear1895
