Brasenia schreberi J.F. Gmel.

Water Shield

© SRTurner

Family - Cabombaceae

Habit - Aquatic, perennial, rhizomatous.

Stems - Aquatic slender stolons, potentially to 2 m or more, potentially rooting at nodes, usually submerged but sometimes floating to surface, appearing glabrous, submerged portions thickly coated with mucilage.

Leaves - Alternate, monomorphic, peltate, long-petiolate, entire. Petioles and underside of leaf blades heavily mucilaginous and reddish-purple below. Petioles to 30 cm or more. Blades elliptic, to 14 cm long, 8 cm broad, glabrous and green above, reddish-purple below.

	Leaves.
© SRTurner

	Leaves, upper surface.
© SRTurner

	Leaf lower surface and petiole with mucilage.
© SRTurner

	Petiole and underside of leaf.
© DETenaglia

Inflorescence - Single axillary flowers on long red peduncles. Flowers stalks erect at flowering, holding flowers 5-10 cm above water surface, bending to become submerged at fruiting.

Flowers - Perianth curled outward and downward at flowering, later becoming erect and more or less enfolding the developing fruits. Sepals 3 or less commonly 4, 13-15 mm long, strap-shaped, green on the outer surface, reddish purple to maroon on the inner surface. Petals 3 or less commonly 4, slightly longer and narrower than the sepals, strap-shaped, reddish purple to maroon, glabrous. Stamens 18-36 (rarely more), erect. Filaments to 1.2 cm long, pink to purple near apex, glabrous. Anthers deep purple, 3.1 mm long. Pistils 4-18, the ovaries 5 mm long, pink, glabrous or pubescent at apex, unilocular, ovules 1-4 per locule. Style 5mm long, deep purple at apex, with a linear stigmatic region along a side toward the tip. Placentation parietal.

	Flower.
© DETenaglia

Fruits - Achenelike, 6-10 mm long, club-shaped to peanut-shaped, tapered to the persistent style, maturing submerged. Seeds 2.5-4.0 mm long, oblong to oblong-ovate in outline, the surface finely pebbled, grayish brown to yellowish brown.

Flowering - May - September.

Habitat - Aquatic in ponds, lakes, sloughs and swamps.

Origin - Native to the U.S., Central America, Asia, Australia, Africa.

Lookalikes - Potamogeton species.

Other info. - This plant occurs in widely scattered locations in Missouri, predominantly but not exclusively in the southern and eastern parts of the state. Its wider distribution includes both western and eastern states of the continental U.S., though it is missing from some mountain and southwestern states. Distributional data suggest that it is not particularly common, though it is probably undercollected due to the general inconvenience of gathering aquatic specimens. It is easy to identify in the field by virtue of its peltate leaves and the thickly mucilaginous petioles and leaf undersides.

Water shield provides food for waterfowl, and the tuberous roots were eaten by Native Americans in California. Young leaves have been used as salad greens in Japan, and can sometimes be found packaged for sale in international grocery stores. The floating leaves afford shade and shelter for fish, and good fishing can often be found where the plant is abundant. It can become a nuisance in shallow ponds and lakes, growing so thickly as to block light and gas exchange. The mucilaginous coating on plant parts may retard loss of water during times of drought, and may also discourage herbivory.

Photographs taken at the Irish Wilderness, Mark Twain National Forest, Oregon County, MO., 7-15-00 (DETenaglia); also at Meramec Conservation Area, Franklin County, MO, 8-12-2015, and Duck Creek Conservation Area, 8-17-2021 (SRTurner).