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 Introduction
to the Use of the Common Grasses Guide
The grasses, sedges
and rushes are a large group of some 13,600 species, surpassed only by the
orchids and sunflowers in number of taxa. Overall, they are a difficult
group to determine to species. Their identification is often a matter of
interpretation of the flower
The grasses (Family Poaceae) have stems that are usually jointed and
round to elliptical in cross-section. The sedges (Family Cyperaceae) have
stems that are usually triangular, at least in cross-section. The rushes
(Family Juncaceae) have stems that are rounded and solid. For a more
complete comparison, see the box below.
Most species of sedges and rushes are associated with
moist habitats, some being semi-aquatic, while others are well adapted to
fairly dry conditions. The grasses are well adapted to a variety of
habitats from wet to very dry. The grasses are the most common family of
plants found in the prairie biome.
The species here represent only a small number of the
total found in southeast Kansas and adjoining states. Credit goes to Dr.
Craig Freeman, McGregor Herbarium, University of Kansas for verifying the
name of several of the sedges and rushes and the identification of others.
However, Dr. Stephen Timme takes responsibility for all names assigned to
the photographs.
For more
information pertaining to any of the species or to note any errors, contact Dr. Stephen L. Timme
at
slt@pittstate.edu.
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Quick Guide to Separating Grasses, Sedges, and Rushes
| Family |
Stem |
Leaf |
Flower |
Fruit |
| Rushes
(Family
Juncaceae) |
rounded and solid |
alternate,
3-ranked, basal or along the lower part of the stem, linear, flat or
rounded, sheath usually open |
usually bisexual,
inconspicuous, tepals 6, stamens 6, sometimes 3, ovary superior |
capsule |
| Sedges
(Family
Cyperaceae) |
usually triangular, at least in cross-section |
alternate, 3-ranked,
sheath closed |
bisexual or unisexual (plants then monoecious),
each subtended by a bract, tepals lacking or reduced to 3-6 scales,
bristles or hairs, stamens 1-3, sometimes 6, ovary superior |
Achene (nutlet) |
| Grasses
(Family
Poaceae) |
jointed, round to
elliptical, at least in cross-section |
alternate,
3-ranked, sheaths tightly wrapped around the stem, with overlapping
margins, ligule present |
in spikelets, each
with 2 basal bracts (glumes) and 1 to many florets made up of bracts
(lemma and palea) subtending the flower, bisexual or unisexual (plants
then monoecious or dioecious), lodicules 2, stamens 1-6, sometimes
numerous, ovary superior, stigmas plumose |
caryopsis (grain), one seeded, fruit wall fused
to the seed |
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