Silphium is a valuable fennel-like plant that grows only in certain parts of the southern coast of the Chaska Sea, considered to be worth more than its weight in gold. Resin derived from silphium is greatly prized for both culinary and medicinal purposes by those that live around the Chaska, and especially by the upper classes of Viridia, for whom its use is a status symbol.
Silphium is only found in certain small regions, primarily in the rocky semi-arid landscape around the city of Ophir, which has become quite wealthy through its trade. Its rarity and therefore cost are largely a result of its resistance to cultivation; effectively all silphium is found and harvested wild. In recent decades the farmers in Ellu and Ashnan have both experimented with growing silphium in more intensive environments, either in greenhouses or in plantation-like arrangements, but even with magical aids the plant refuses to grow when not seeded naturally in its native environment.