Ginseng is each of eleven species of slow-growing perennial plants with fleshy roots, in the Panax genus, in the family Araliaceae. It grows in the Northern Hemisphere in eastern Asia (mostly northern China, Korea, and eastern Siberia), typically in cooler climates; Panax vietnamensis, discovered in Vietnam, is the southernmost ginseng found. Korean ginseng is widely considered the best quality. This article focuses on the Series Panax ginsengs, which are the adaptogenic herbs, principally Panax ginseng and P. quinquefolius. Ginseng is characterized by the presence of ginsenosides. Siberian ginseng (Eleutherococcus senticosus) is not a true ginseng, but a different plant that was renamed as "Siberian ginseng" as a marketing ploy; instead of a fleshy root, it has a woody root; instead of ginsenosides, eleutherosides is the active compound. Eleutherosides are classified as another adaptogen. A powder is a dry, bulk solid composed of a large number of very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms powder and granular are sometimes used to distinguish separate classes of material. In particular, powders refer to those granular materials that have the finer grain sizes, and that therefore have a greater tendency to form clumps when flowing. Granulars refers to the coarser granular materials that do not tend to form clumps except when wet.