. Contributions from the New York Botanical Garden. Plants. On the lower side of the petiole of the primary leaves, a woody thickening is developed (Figs, ii and 12, zc) which increases in firmness as the leaf matures. This arises from the cortex, which even in the bud is proliferated to form a thickened area on the outer side of the base of each leaf (Fig. i, c). As the leaf emerges from the bud a conical portion of the cortex on the lower side of the petiole begins to lose its paren- chymatous character. The cells lengthen, their ends become pointed (Fig. 2, s) and their walls thicken ; thes
. Contributions from the New York Botanical Garden. Plants. On the lower side of the petiole of the primary leaves, a woody thickening is developed (Figs, ii and 12, zc) which increases in firmness as the leaf matures. This arises from the cortex, which even in the bud is proliferated to form a thickened area on the outer side of the base of each leaf (Fig. i, c). As the leaf emerges from the bud a conical portion of the cortex on the lower side of the petiole begins to lose its paren- chymatous character. The cells lengthen, their ends become pointed (Fig. 2, s) and their walls thicken ; these changes are ,, . , , , J accompanied by a diminution in their Fig. I. Section through bud. '^ •' a, young leaf; ^, cortex, thick- lumina (FiG. 3, s). With phloroglucin ened to form spine; v, vascular and hydrochloric acid they take the ^^^^^^- violet color characteristic of sclerenchy- matous cells. The conversion of the parenchyma into scleren- chyma is incomplete in F. splendcns, and a slender cone shaped mass of thin-walled cells extends about two thirds of the distance from the base toward the tip of the newly formed spine. This is illustrated by the diagrams of s longitudinal and transverse sec- j.^^ ^ p^^^;^^ ^^ longitudinal section tions shown in Figs. 4, 6 and 7, through petiole, b, cortex ; t, separating /. About the time when the layer; 5, sclerenchyma. leaf-blade is cast off, the parenchyma-core disintegrates and a hol- low spine remains. In Foiiqiiieria Macdoiigalii, on the other hand, almost the entire mass of the cor- tex on the outer (lower) side of the petiole is transformed into sclerenchyma, making a solid heavy spine (Figs. 5 and 8, s). The growth of the leaf and Fig. 3. Portion of transverse section the development of the spine is roug pe 10 e. accompanied by the differentiation of a separatory layer of thin-walled, elongated cells (Figs. 2 and. Please note that these images are extracted from scanned page images that may have been digitally enhanced for
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectplants, bookyear1899
