This is a cyanotype botanical illustration of seaweed, specifically *Sargassum plumosum*. The image is dominated by a deep teal or blue background, characteristic of cyanotypes. Two specimens of *Sargassum plumosum* are prominently displayed. The larger specimen is positioned across the upper portion of the image, arching slightly. It features numerous delicate, feather-like branches with small, rounded leaf-like structures. The second, smaller specimen is located in the lower right corner, mirroring the branching pattern of the first. The seaweed appears as a pale, almost white silhouette against the blue background, creating a high-contrast image. At the bottom center, there is handwritten text in a delicate script that reads 'Sargassum plumosum'. The overall aesthetic is reminiscent of early botanical studies and scientific documentation, with a vintage and artistic quality.