This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Habit of the several species various. Flowers sessile or very nearly so in the spathe-like involucre. Perianth none. Stamens 2, their filaments united to near the summit; anthers 2, oblong or oval. Staminodia 2, filiform. Ovary ovoid, 2-celled; stigmas 2, nearly erect, short, subulate. Capsule ovoid, 6-10-ribbed, 2-valved. [Greek, stalked-stamens.]
About 12 species of rather wide geographic distribution, the following typical. Besides the following:, another occurs in the southern United States.
Podostemum ceratophyllum Michx. Fl. Bor. Am. 2: 165. 1803.
Plant dark green, rather stiff, firmly attached to stones in running water, densely tufted, 1'-10' long, the leaves narrowly linear, sheathing at the base, commonly split above into almost filiform segments or lobes. Flowers less than 1" broad, at length bursting from the spathes; capsule oblong-oval, rather more than 1" long, obtuse, borne on a stipe of about its own length, 8-ribbed; stigmas at length recurved.
Firmly attached to stones in shallow streams, New Brunswick to Ontario and Minnesota, south to Georgia, Alabama and Kentucky. July-Sept.