The Brasenia genus and
Brasenia schreberi J. F. Gmelin
Remark
The words or terms in red
(actually dark orange) in the text are defined in a
glossary.
Brasenia is a monotypic genus
sporadically distributed throughout the Americas, Asia, Australia, and Africa,
with Brasenia schreberi its single
species.
Brasenia is one of eight genera
that comprise the two families
of Nymphaeales (the water lilies) the Cabombaceae
family (with the genera Brasenia and Cabomba) and the
Nymphaeaceae family.
The Nymphaeales are among the most primitive
angiosperm.
Brasenia schreberi
is a floating-leaved
perennial plant that is
native to North America.
Its long leaf stalks reach all the way to the bottom where they
attach to a long creeping
root that is anchored in the mud. Its leaves are oval and shield-shaped. Its
leaf stalks are attached at the centers of the leaf blades. Its submersed parts
and undersides of leaves are covered with a viscous jelly-like substance.
Its flowers are small, dull purple, and emerge from the water on a stalk. Its
chromosome number (2n) is 80.
The plant belongs to the
Cabombaceae
family.
Name
The genus name, given by Johann Christian Daniel von Schreber is for Christoph
Brasen (1738-1774) who might have been the first to collect and describe the
plant. Christoph Brasen was a Danish surgeon, a Moravian missionary, and a
plant collector in Greenland and Labrador. He was the first
superintendent of the Nain Moravian mission in Labrador. He drowned in a storm
that struck the 1774 expedition along the northern coast of Labrador.
During a previous stay in Greenland, he had engaged
in meteorological, botanical, mineralogical, and ornithological observations, to which a manuscript, entitled Some Natural Observations of Brother Brasen
about the Weather, the Plants and Herbs, the Minerals and some Accompanying
Birds testifies.
The schreberi epithet is the
latinization de the name of a German botanist Johann Christian Daniel von
Schreber (1739-1810), professor of natural history and director of the
botanical garden at Erlangen, Bavaria; he was a student of Linnaeus.
Common names
Some of the vernacular names of
Brasenia schreberi are:
Water-shield, Watershield, Water-target, Dollar Bonnet
and Purple Wen-dock.
The French vernacular name is Brasénie de Schreber.
Synonyms
Brasenia schreberi has also been known as:
- Brasenia nymphoides (L.) Baill.
- Brasenia peltata Pursh
- Brasenia purpurea Caspary
- Menyanthes nymphoides Thunb., non L.
- Menyanthes peltata Thunb.
- Hydropeltis purpurea Michx.
Identification
Brasenia schreberi is easy to distinguish from water lilies and other
plants with floating leaves by small oval leaves without a slit or notch.
Furthermore, the clear gelatinous material coating stems and undersides of
leaves is unique.
Description
Brasenia schreberi are aquatic herbs with floating leaves; their
young vegetative parts heavily coated with
mucilage.
Roots
- Long, creeping.
- Anchored in muddy bottom.
Stems
- Up to 6 feet long.
- Covered with slippery gelatinous material.
Leaves
- Alternate.
- Peltate.
- Oval to elliptical.
- From 2 to 5 inches long and half as wide.
- With smooth, unnotched margins.
- With a long centrally-attached red
petiole.
- With the undersides covered with slippery gelatinous material.
- Green above, red below.
Flowers
- About 3/4 inch in diameter.
- Dull purple.
- The (usually 3, sometimes 4) petals slightly longer and narrower than
the (usually 3, sometimes 4) sepals
that are petaloid.
- With 12 to 36 or more stamens.
- Appearing singly above the water on long red
peduncle from the leaf
axils.
- With an unilocular ovary.
- Pollinated by the wind.
- Closing at night.
- Blooming in July in may area, 25 km north of Montréal.
Fruits
- An oblong, segmented
capsule, from 3 to 5 mm long.
- Slightly to strongly fusiform.
- With ovoid seeds from 2 to 3 mm long.
- Ripening underwater and decaying to release their seeds.
Habitat
Brasenia schreberi occurs in shallow lakes, in
oligotrophic or
mesotrophic
ponds and slow streams, and prefers water up to six feet deep.
Distribution
Brasenia schreberi is generously sprinkled throughout the majority of
the U.S. and in Canada; it is widespread but rarely common.
It is found from Nova Scotia and Québec to Minnesota,
south to Florida and Texas. In the west, it is found from British Columbia and
western Montana to Washington and south to California. It is also found in
Mexico, the West Indies, Central and South America, East Asia, Africa, and
Australia. It is known from the fossil record in Europe although it is not known
to grow there currently.
The map on the left show the worldwide distribution; the map on the right
shows the distribution for North America.
Notes
Brasenia schreberi reproduces sexually by seeds and asexually by
rhizomes. In shallow ponds and lakes, Brasenia schreberi
may be the dominant species, and its leaves may cover the entire water surface.
Once established in an area,
growth of other plants may well be inhibited by shading effects of the
densely packed floating leaves. Very dense populations of water shield can
impede small boat navigation and restrict recreational use. The seeds and
vegetative parts are eaten by waterfowl.
In Japan, Brasenia schreberi is used as an ingredient of
miso-shiru (the traditional miso soup). It is also cooked as
Sumisoae or Sanbaizu.
In China, it may be fried as food. When cooked with crucian
carp and bean curd, the soup is said to be fragrant and tasty.
The plants are reported to have antibacterial, antialgal activity and to be
allelopathic to lettuce seedlings.
Gallery
The photos of the gallery were taken either with one of the following:
Minolta DiMAGE 7,
Canon PowerShot A530,
Canon Xt Rebel, usually with the EF-S60mm f/2.8 Macro USM objective,
Fujifilm A 610 and
EPSON Perfection 1650 (scanner).
The title in the window shows the date when the picture was taken,
i.e. jan_30_06... would mean that the photo was taken on the 30th of
January, the 06 is for the 6th picture taken that day.
The month, day and picture number might be followed by a letter which I use
to identify the system used to take the picture.
Click on the thumbnails to get larger view.
The original photos are usually in TIFF format,
the photos shown are generally in JPEG format,
often of dimensions one half (surface one quarter)
for loading time reduction.
Habitat
Plants, petiole
Leaves
Flowers
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