Marsilea mollis

Marsilea mollis B.L. Robinson & Fernald
(Latin: mollis, soft or pliant)

Local names: Mexican water-clover

Similar to M. vestita, but differing as in the key (size of distal sporocarp tooth and leaf pubescence); petioles 1–14 cm long; pinnae 2–17 mm long, 1–16 mm wide (floating leaves in Mexico reported by Mickel & Smith 2004 to be somewhat larger); sporocarps with distal (sometimes called superior) tooth absent or to 0.2 mm long; 2n = 40 (Lesho 1994). Mud or in shallow water, desert washes; known from only one TX collection from Limpia Canyon, Davis Mts., Jeff Davis Co. (Hinkley s.n., 1935, TEX-LL, annotated D.M. Johnson; Johnson 1986, 1993a); AZ and TX, also Mexico to South America. Sporulating May–Oct. Johnson (1993a) indicated that “the name M. Mexicana A. Braun has sometimes been misapplied to this species.” Johnson (1993a) also noted that the red or brown streaks on the pinnae, supposedly characteristic of this species, actually can be found on floating leaves of many other species. Although known from desert habitats, this species can avoid drought by effectively becoming annual. If drought occurs, the plants die, and after heavy rains their life cycle simply begins again with spore germination—the spores having been protected by the very resistant sporocarps (Heitz 2010). Given its rareness and limited distribution in the state, we consider this species to be of conservation concern in TX.

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