PETIOLES: 1–35 cm long, glabrous or sparsely appressed-hairy. LEAFLETS: 5–22 mm long, wedge-shaped to broadly wedge-shaped, broadly rounded to nearly truncate at the tips, often slightly asymmetrically cuneate, glabrous to more commonly moderately pilose on both surfaces, the lateral margins straight or more commonly 1 margin shallowly concave. SPOROCARPS: solitary, appearing more or less perpendicular to the peduncle produced from the tip of a short peduncle attached at or rarely just above the petiole base, (3.6–)4–7 mm long, 3–6 mm wide, oblong-quadrangular to broadly oval in outline, the tooth distal to the stalk tip well-developed, 0.4–1.2 mm long, sharply and narrowly triangular (Fig. 2B). MEGASPORES: 450–515 μm in diameter (excluding the apical papilla). MICROSPORES: 65–80 μm in diameter. 2n = 40. NOTES: Shallow water and margins of ponds, lakes, stock tanks, reservoirs, and streams: Cochise, Mohave, Pima, Pinal, Santa Cruz, Yuma cos. (Fig. 1B); 450–1650 m (1400–5400 ft); WA to MN, s to CA. REFERENCES: Windham, M. D. and G. Yatskievych. 2009. Vascular Plants of Arizona: Marsileaceae. CANOTIA 5 (1): 30–33.