Brasenia schreberi

Water Shield

Water Shield
Photo Courtesy USDA Plants Database

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The natural history of the northwoods

Name:

• Brasenia, named for Christoph Brasen, 1774, Moravian missionary and plant collector in Greenland and Labrador
• schreberi, from the Latin, "of Schreber, Schreber's". Named for German botanist Johann Christian Daniel von Schreber (1739-1810), a student of Linnaeus.
• Common Name, from the shape of the floating leaf
• Other common names include Dollar Bonnet, Purple Wen-dock, Schreber's Watershield, brasénie de Schreber (Qué), Junsai (Jap)

Taxonomy:

• Kingdom Plantae, the Plants
  • Division Magnoliophyta, the Angiosperms (flowering plants)
    • Class Magnoliopsida, the Dicotyledons
    • Subclass Magnoliidae
      • Order Nymphaeales, the Water Lilies
        • Family Cabombaceae
          • Genus Brasenia, the Watershields
• Taxonomic Serial Number: 18370
• Also known as Brasenia peltata

Description:

• Floating leaf, aquatic perennial herb of shallow lakes and ponds, slow rivers.
• Leaves alternate, oval to elliptical, 2"-5" long and half as wide, with smooth, unnotched edges and centrally-attached leaf stems. Undersides covered with slippery gelatinous material.
• Stem to 6' in length; trails through water, also covered with slippery gelatinous material.
• Rootstalk long, creeping, anchored in muddy bottom.
• Flowers small (about ¾" in diameter), dull purple, petals slightly longer and narrower than sepals, appearing singly above the water on long stalks from leaf axils. Flowers June to September.
  • Sepals usually 3, sometimes 4
  • Petals usually 3, sometimes 4
  • Stamens 12-18
• Fruit oblong, segmented capsule, 3-5mm long, ripening July and after.
• Seed ovoid, 2-3 mm long

Identification:

• Distinguished from water lillies by small oval leaves without a slit or notch
• Clear gelatinous material coating stems and undersides of leaves is unique.

Distribution:

• Nova Scotia and Quebec to Minnesota, south to Florida and Texas. In the west, from British Columbia and western Montana to Washington and south to California.
• Also Mexico, West Indies, Central and South America, East Asia, Africa, and Australia.

Habitat:

• Oligotrophic or mesotrophic ponds, sluggish streams, and shallow lakes, to depths of 6'-9'
• In favorable settings it can cover large areas and inhibit boating and swimming.
• In the BWCA, look for it on the Chub and Louse Rivers; offshore of portages

Associates:

• Birds: Ducks, geese, and other waterfowl eat the seeds, leaves, and underwater stems
• Herps: Some freshwater frogs use the stalks for building nests.
• Fish: Provides shade and shelter

History:

• Brasenia is known from the fossil record in Europe although it is not known to grow there currently.

Uses:

• In Japan, an ingredient of miso-shiru (miso soup). Also cooked as Sumisoae or Sanbaizu.
• In China, may be fried as food. When cooked with crucian carp and bean curd, the soup is said to be fragrant and tasty.

Reproduction:

• Sexually by seed, flowering late spring through summer. Pollinated by wind.
• Asexually by rhizomes

Propagation:

• From seeds collected late summer from underwater seed casings, and sown immediately in trays containing wet mud. Cover the seedpots with water and then increase depth as plants grow.
• From division of rootstalk

Cultivation:

• Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
• Cultural Requirements
• Sun - full
• Soil - rich
• Water - still, lime-free, to 6' deep
• A good plant for the water garden but difficult to establish.

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