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"Radial longitudinal section through a hydatode from the leaf margin of Primula sinensis. i, upper, and j, lower epidermis; h, palisade cell; e, thin-walled parenchyma, called epithem; g, intercellular space; f, guard cell of a water stoma; k, tracheal elements." -Stevens, 1916

P. Sinensus Hydatode

"Radial longitudinal section through a hydatode from the leaf margin of Primula sinensis. i, upper,…

"Portion of a cross section throughout the stem of Dracaena marginata. P, parenchyma of cortex. V, meristematic zone of the pericycle by the activity of which the stem increases in diameter, with the addition of new vascular bundles. M, mature vascular bundle. N, nearly mature vascular bundle. O, newly formed procambium strand from which a vascular bundle is to arise. B, beginning of a procambium strand by the division of cells in the meristematic zone. F, parenchyma of the fundamental tissue." -Stevens, 1916

D. Marginata Stem

"Portion of a cross section throughout the stem of Dracaena marginata. P, parenchyma of cortex. V, meristematic…

"Semi-diagrammatic cross section of a leaf showing by arrows how the water passes from the tracheal elements of a vein into the border parenchyma cells, and thence into the palisade and spongy parenchyma, from which it evaporates into the intercellular spaces and passes from the leaf through the stomata. a, upper epidermis; b, lower epidermis; c, palisade parenchyma; g, spongy parenchyma; d, border parenchyma; e, tracheal elements; and the stippled cells bellow e, the phloem cells." -Stevens, 1916

Leaf Water Flow

"Semi-diagrammatic cross section of a leaf showing by arrows how the water passes from the tracheal…

Stages in the development of the elements of the xylem. "D, steps in the formation of wood parenchyma from cambial or procambial cells. 1, group of cambial or procambial cells; 2, the same enlarged in all dimensions; 3, the same with walls thickened and pitted; 4 and 5 show the same stages as 2 and 3, but here the cells have enlarged radially or tangentially more than they have vertically. The walls of these cells are apt to become lignified, but the cells are longer lived than the wood fibers." -Stevens, 1916

Xylem Development 4

Stages in the development of the elements of the xylem. "D, steps in the formation of wood parenchyma…