noun
definition
A bristle or hair
definition
The stalk of a moss sporangium, or occasionally in a liverwort.
Examples of seta in a Sentence
In the vibraculum the part representing the zooecium is relatively smaller, and the mandible has become the "seta," an elongated chitinous lash which projects far beyond the zooecial portion of the structure.
Frequently, also, a considerable differentiation of vegetative tissue occurs in the wall of the spore-capsule itself, and in some of the higher forms a special assimilating and transpiring organ situated just below the capsule at the top of the seta, with a richly lacunar chlorophyllous parenchyma and stomata like those of the wall of the capsule in the Anthocerotean liverworts.
The central hydrom strand in the seta of the sporogonium of most mosses has already been alluded to.
Tomopteris is remarkable for the fact that the hammer-shaped prostomium has paired ventral processes each with a single seta.
The external segments are usually definable by the setae; and if the setae are absent, as in the anterior segments a, Penial seta of Perichaeta ceylonica.
Besides this there is usually a living conducting tissue, sometimes differentiated as leptom, forming a mantle round the hydrom, and bounded externally by a more or less well-differentiated endodermis, abutting on an irregularly cylindrical lacuna; the latter separates the central conducting cylinder from the cortex of the seta, which, like the cortex of the gametophyte stem, is usually differentiated into an outer thick-walled stereom and an inner starchy parenchyma.
They are disposed in two groups on either side, corresponding in the Polychaeta to the parapodia; the two bundles are commonly reduced among the earthworms to two pairs of setae or even to a single seta.