From Plant Press, Vol. 20, No. 1, January 2017.
Stunningly underwhelming, species of the genus Isoetes, commonly known as quillworts, bear amazing similarity to grass plants with which they are often confused. The U.S. state of Mississippi has now given its name to a new species of the enigmatic quillwort group. The study was published in the open access journal PhytoKeys.
The new species, Isoetes mississippiensis, is an unusually large representative of the genus, first discovered in 1996 by Steve Leonard. For years it was known by the informal name “Big Dog,” a reference to its size.
Further microscopic and cytological study by Rebecca Bray, Lytton Musselman, and Peter Schafran (Old Dominion University), and W. Carl Taylor (National Museum of Natural History) revealed that this is in fact a new species, rather than a strange form of the wide-ranging Midwestern I. melanopoda. The megaspores of I. mississippiensis appear smooth under a hand lens (~30X magnification), only revealing their echinate micro-ornamentation with magnification >200X. Megaspores of I. melanopoda generally display bumps and ridges visible with a hand lens. The coverage of vela over the sporangia also separates these species, where I. mississippiensis has 15-33 percent coverage and I. melanopoda has 5-15 percent coverage. Isoetes mississippiensis is a basic diploid, and is a parent of a tetraploid taxon also occurring in southern Mississippi (Zimmer et al. in prep).