Thank you once again to Marianne, aka marcella2@Flickr, for contributing a photograph to Botany Photo of the Day (original image | Botany Photo of the Day Flickr Pool). Always glad to have an image from a vascular plant family that hasn’t yet been featured on BPotD!
Butomus umbellatus is the sole member of the monotypic genus Butomus, itself in turn the sole member of the monotypic Butomaceae. The closest living relatives to this freshwater aquatic are species in the Hydrocharitaceae (a family that includes both freshwater and marine aquatics).
Known as flowering rush (though it isn’t a true rush), Butomus umbellatus has a distribution that spans much of Europe and western Asia. Introduction into North America (believed to be for use as a garden plant) has resulted in widespread dispersal through the north temperate parts of the continent, and it is considered an invasive species. The page on Butomus umbellatus from the Noxious Weeds of King County explains the difficulty in controlling this species once it has established, so preventing dispersal is paramount.
On a technical BPotD note: a few people have noticed that BPotD images are failing to display completely on a consistent basis. I believe this is because of the IUCN Red List “Species of the Day” box that appears at the bottom of the daily posting. The “Species of the Day” is an embedded feed — meaning that for it to display, the IUCN web server is contacted each time a BPotD daily page is loaded and then the IUCN web server supplies the graphic. I think that from time to time, the IUCN web server gets overloaded — and this halts the loading of the BPotD page (and images) while your browser tries (and tries) to gather the information it needs from the IUCN server. Two possible solutions: 1) you can reload / refresh the page when this does occur (Ctrl-R on a PC with Firefox, or hit the reload button); or 2) I can remove the IUCN Red List Species of the Day box (which will be done anyway come Jan. 1). My preference is for option 1.