Dear John and other interested in this topic: With respect to the structure of Eleocharis dulcis, why not compare that of Crocosmia? They are very similar. Everyone who knows the difference between a bulb and a corm will say that Crocosmia grows from a corm. But dig a Crocosmia at this time of year, and what do you see? You see rhizomes, very thin rhizomes, at the tips of which are small corms. How is that different from what is seen in Eleocharis? I've never known anyone to refer to these small developing corms as "rhizome tubers", yet they develop in a manner similar to the development of rhizome tubers. Jim McKenney