vegetation is the final parameter of the wetland definition. In general
terms, hydrophytic vegetation is plant-life that thrives in wet conditions.
More technically put, the term hydrophytic vegetation, as it relates
to wetland identification, is defined as, "the sum total of macrophytic
plant life that occurs in areas where the frequency and duration of inundation
or soil saturation produce permanently or periodically saturated soils
of sufficient duration to exert a controlling influence on the plant species
present" (U.S. Army Corps of Engineers 1987).
conjunction with the National Wetlands Inventory (NWI), a nationwide effort
to map all of the wetlands in the United States, the U.S. Fish and Wildlife
Service (USF&WS) has developed a National
List of Plant Species that Occur in Wetlands. According to this
list, there are five categories in which plant species that appear in
wetlands may be placed. These categories are as follows:
(OBL)-Occur almost always (estimated probability >99 percent) under
natural conditions in wetlands.
Wetland (FACW)-Usually occur in wetlands (estimated probability 67-99
percent), but occasionally found in non-wetlands (estimated probability
(FAC)*-Equally likely to occur in wetlands or non-wetlands (estimated
probability 34-66 percent).
Upland (FACU)-Usually occur in non-wetlands (estimated probability
67-99 percent), but occasionally found in wetlands (estimated probability
(UPL)-Occur almost always (estimated probability >99 percent under
natural conditions in non-wetlands
Those plant species classified as Facultative can further be classified
as FAC+ or FAC-. This designation reflects the regional frequency of occurrence
of that species in wetlands. A FAC+ species is one that is more frequently
found in wetlands in a specific region, whereas a FAC- is found in wetlands
less frequently (Reed 1988).
making a wetland determination and/or delineation, emphasis is placed
on the total assemblage of dominant
macrophytic plant species rather than on the presence of a particular
indicator species. Thus, "the presence of scattered individuals of an
upland plant species in a community dominated by hydrophytic species is
not a sufficient basis for concluding that the area is an upland community.
Likewise, the presence of a few individuals of a hydrophytic species in
a community dominated by upland species is not a sufficient basis for
concluding that the area is a wetland community" (U.S. Army Corps of Engineers
a background in botany, it may be difficult for an individual to discern
if the plant communities present are indicative of a wetland or upland
landscape. Even if an individual can not taxonomically name the plant
species in a particular area, there are some clues one can look for which
will help identify many plant species as hydrophytic. To survive in anaerobic,
hydrologic conditions, many plants have developed some obvious physical
adaptations to facilitate the capturing and transporting of oxygen. Some
of these adaptations include:
people associate plant species such as cattails, waterlilies, and duckweed
with wetland areas, but require additional information to identify other
obligate wetland species such as buttonbush, bulrush, and arrowhead. IDNR
has in the past published a Field Guide to the Wetlands of Illinois (now out of print) which has full
color photographs, classifications, and detailed descriptions of 100 of
the most common wetland plants in Illinois. This paperback book is an
excellent resource for individuals interested in learning how to identify
wetland vegetation. It also contains color photographs, classifications,
and detailed descriptions of 13 different "typical" Illinois wetland types
(Illinois Department of Natural Resources 1988).
Contact your local library to see if it has a copy.