in botany, a genus of submarine plants, belonging to the cryptogamia class.

The fucus consists of a tough matter, formed into a kind of leaves, which are flat and variously divaricated; and which have some appearance of fructification, in punctated tubercles, covering oblong vehicles, supposed by Linnæus to be male flowers; and smooth roundish vehicles, hollow and interwoven with filaments, which appear to him to be female flowers. There are 34 species of fucus, or sea-wrack, many of them to be found on our coasts.

The ancients used a purple sea-plant to dry woollen and linen things of that colour, and called it fucus. The dye was very beautiful, but not lasting; for it soon began to change, and in time went wholly off. This is the account Theophratus gives of it.

The women of those times also used something called fucus, to stain their cheeks red; and many have supposed, from the same word expressing both, that the same substance was used on both occasions. But this, on a strict inquiry, proves not to be the case. The Greeks called every thing fucus, that would stain or paint the flesh. But this peculiar substance used by the women to paint their cheeks was distinguished from the others by the name of rizion among the more correct writers, and was indeed a root brought from Syria into Greece. The Latins, in imitation of the Greek name, called this root radicula, and Pliny very erroneously confounds the plant with the radix lunaria, or fruthion of the Greeks.

The word fucus was in those times become such an universal name for paint, that the Greeks and Romans had a fucus metallicus, which was the cerus used for painting the neck and arms white; after which they used the purpurifimus, or red fucus of the rizium, to give give the colour to the cheeks. In after-times they also used a peculiar fucus or paint for this purpose; prepared of the Creta argentaria, or silver-chalk, and some of the rich purple dyes that were in use at that time: and this seems to have been very little different from our rose-pink; a colour commonly sold at the colour-shops, and used on like occasions.