Helianthoida

( Zool.) An order of Polyps, embracing those which have a well-developed abactinal region, conical or cylindrical tentacles around the mouth, and the ambulacral square always open. Helianthus, n. [Gr. helios, the sun, anthos, flower.] ( Bot.) The Sun-flower, a gen. of plants, order Aster acer. The species H. annuus is a well-known annual. It is appropriately named the sun-flower, as its large circular head of florets, surrounded by golden rays, forms a complete ideal representation of the sun; moreover, it never ceases to adore the sun while the earth is illuminatad by his light; for when he sinks in the west, the flowers of Helianthus are turned towards him, and when he rises in the east, they are ready to be cherished by his first beams. Some writers on botany deny that the flowers turn with the sun; but their observations do not agree with popular experience. There are varieties of H. annuus with double flowers, the tubular florets being all changed into ligulate ones, like those of the ray. The pith of the stem contains nitrate of potash, and is sometimes used in the preparation of moxas. The fruits have lately been employed as an ingredient in a kind of soap called sunflower-soap. The species H. tuberosus produce the tubers known as Jerusalem artichokes, which are much eaten, like potatoes. The word Jerusalem is merely a corruption of the Italian girasole . Hel'ical, a. [From Gr. heliz. See HELIX.] Pertaining or relating to a helix; spiral; winding; coiled in a spiral form.