Widgeon Grass
Ruppia maritima
Native to Chesapeake Bay
- Family - Ruppiaceae
- Distribution - Widgeon grass tolerates a wide range of
salinity, from the slightly brackish upper and mid-Bay tributaries to near
seawater salinity in the lower Bay, and in hypersaline salt pannes. Widgeon
grass has also been reported to grow in the freshwater parts of some estuaries
and in nontidal waters. In more saline lower Bay areas, widgeon grass and
eelgrass are the dominant bay grass species. Widgeon grass is most common in shallow
areas with sandy substrates, although it occasionally grows on soft, muddy
sediments. High wave action can damage the slender stems and leaves of widgeon
grass.
- Recognition - Linear, thread-like leaves are 3 to 10 cm
(1 ¼ in to 4 in) long and 0.5 mm (<1/32 in) wide; these are arranged alternately
along slender, branching stems. Leaves have a basal sheath and a rounded tip.
Widgeon grass has an extensive root system of branched, creeping rhizomes that
lack tubers. There are two growth forms of widgeon grass in Chesapeake Bay: An
upright, highly branched form during flowering (summer); and a creeping growth
form with the leaves appearing basal.
- Ecological Significance - Widgeon grass is one of the more
valuable waterfowl food sources and all parts of the plant have excellent
nutritional value. Widgeon grass is also important for its ability to tolerate a
wide range of salinity and is found in brackish to high salinity waters. In
higher salinity water, widgeon grass is often found growing together with
eelgrass, with the widgeon grass more common in
shallow areas and the eelgrass more common in deeper water. Widgeon grass can
also be found growing in ditches alongside roads and agricultural fields where
it derives its other common name, ditch grass.
- Similar Species - When not in flower or with seeds, widgeon
grass closely resembles horned pondweed (Zanichellia
palustris) and sago pondweed (Stuckenia
pectinata). Unlike widgeon grass, however, horned pondweed has opposite to
whorled leaves, and the leaves of sago pondweed are in bushy clusters. When in
seed, the single seed pods that form at the base of fan-shaped clusters of short
stalks distinguish widgeon grass. Sago pondweed seeds are in terminal clusters,
and horned pondweed seeds occur in groups of 2-4, are horn-shaped and form in
the leaf axils.
- Reproduction - Widgeon grass reproduces asexually and sexually.
Asexual reproduction occurs by emergence of new stems from the root-rhizome
system. Sexual reproduction in late-summer produces two perfect flowers enclosed
in a basal sheath of leaves. The flowers extend towards the water surface on a
peduncle or flower-stalk. Pollen released from stamen float on the water surface
until contacting one of the extended pistils. Fertilized flowers produce four
black, oval-shaped fruits with pointed tips. Individual fruits extend on stalks,
which occur in clusters of eight stalks.
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