Stem

Collier's New Encyclopedia (1921)

in botany, the ascending axis of a plant. It seeks the light, strives to expose itself to the air, and expands itself to the utmost extent of its nature to the solar rays. With regard to direction, it may be erect, pendulous, nodding, decumbent, flexuose, creeping, or climbing. It is generally cylindrical; but may be triangular, as in Carex; square, as in the Labiata; two-edged, as in some Cacti; filiform, as in flax; or leaf-like, as in Ruscus. It consists of bundles of vascular and woody tissue embedded in various ways in cellular substance, the whole being inclosed with an epidermis. Stems may be aërial or underground. The most highly developed form of the former is the trunk of a tree, the next is that of a shrub. There are also herbaceous stems. Sometimes a plant appears stemless; only, however, because the stem is short enough to be overlooked. In duration a stem nual, biennial, or perennial ture is may be exogenous, or acrogenous. Aërial stems branch and bear leaves, flowers, and fruit. An underground stem, such as the rhizome or the tuber, is frequently mistaken for a root. The potato plant has a subterranean stem. In mechanics, the projecting-rod which guides a valve in its reciprocations. In mining, a day's work. In music, the line attached to the head of a note. All notes used in modern music but the semibreve, or whole note, have stems; quavers and their sub-divisions have stems and hooks. In writing a "single part" for a voice or instrument, it is usual to turn the stems of notes lying below the middle line of the stave upward, of notes lying above the middle line downward. Notes on the middle line have their stems up or down as seems best. In a "short score," as for four parts the stems of the higher part in each stave are turned up, those of the lower part down. In ornithology, the main stalk of the feather bearing all the other external parts, and usually resembling a greatly elongated cone. At the lower part which is inserted in the skin, it is cylindrical, hollow, and transparent; higher up it is filled with a cellular pith. The parenchymatous portion of the stem is called the shaft, and it is from the flattened sides of this that the barbs issue. In shipbuilding, the upright piece of timber or bar of iron at the fore end of a vessel, to which the forward ends of the stakes are united. With wooden stems the lower end is scarfed into the keel. The upper end supports the bowsprit, and in the obtuse angle is the figure head. The advanced edge of the stem is the cut-water. It is usually marked with a scale of feet, showing the perpendicular height above the keel, so as to mark the draught of water at the forepart. Called also stem post. In vehicles, the bar to which the bow of a falling hood is hinged.