Umm... yeah.... I think most folks are unfamiliar with sizes of different screen material. And new gardeners are likely to be unfamiliar with even easy seeds like petunia. It's possible some people have only grown pelleted petunia, or maybe none at all.
Veteran seed savers can generally identify seeds after a few years of collecting them. It's the beginners who might find pictures helpful. I know they helped me a lot as a newbie. Something of well-known size like a coin might be of added value, but really, a simple photo of most seeds is pretty adequate without any size comparison I think.
In some cases including chaff in the same photo, labeled as such, might be helpful. e.g.sometimes beginners can't differentiate between chaff and seeds in echinacea cones. Displaying both, labeled, in a photo makes the difference obvious.
Karen
