[[File:Illustrated diagram of a fen.jpg|thumb|260px]]
A '''fen''' is one of the
six{{cn|date=June 2014}}
four main types of [[wetland]]
,
and
the
one
others
of
being
two
grassy
types
[[marsh]]es,
of
forested [[
mire
swamp]]
s,
(the
and
other
peaty
being
[[bog]]s. Along with bogs, fens are a
kind of [[
bog
mire]]
).
It
Fens
is
are usually fed by mineral-rich surface water or groundwater.<ref>[[#Godwin|Godwin ''et al.'' (2002)]].</ref>
Fens
They are characterised by their water chemistry, which is [[pH|pH neutral]] or [[alkali]]ne, with relatively high dissolved [[mineral]] levels but few other [[plant nutrition|plant nutrient]]s. They are usually dominated by grasses and sedges, and typically have brown mosses in general including ''[[Scorpidium]]'' or ''[[Drepanocladus]]''.<ref name="Keddy_8">[[#Keddy|Keddy (2010)]], p. 8.</ref> Fens frequently have a high diversity of other plant species including carnivorous plants such as ''[[Pinguicula]]''.<ref>[[#Wheeler|Wheeler & Giller (1982)]]</ref><ref>[[#Keddy|Keddy (2010)]], Chapter 9.</ref> They may also occur along large lakes and rivers where seasonal changes in water level maintain wet soils with few woody plants.<ref>[[#Charlton|Charlton & Hilts (1989)]]</ref> The distribution of individual species of fen plants is often closely connected to water regimes and nutrient concentrations.<ref>[[#Slack|Slack ''et al.'' (1980)]]</ref><ref>[[#Schröder|Schröder ''et al.'' (2005)]]</ref>
Fens have a characteristic set of plant species, which sometimes provide the best indicators of environmental conditions. For example, fen indicator species in New York State include ''[[Carex|Carex flava]]'', ''[[Cladium mariscoides]]'', ''[[Potentilla fruticosa]]'', ''[[Pogonia ophioglossoides]]'' and ''[[Parnassia glauca]]''.<ref>[[#Godwin|Godwin ''et al.'' (2002)]], Table 3.</ref>
