A dry, indehiscent one-seeded
fruit in which the seed is readily separated from the fruit wall. In Carex, located inside a perigynium. The term "achene" is
sometimes restricted to fruits developed from a superior ovary, as in buckwheat (Fagopyrum and other members of the Polygonaceae), achene-like fruits developed from inferior ovaries being called cypselas. See also caryopsis.
In biology, structures having the same function but
different evolutionary origins. The fins of fish and whales are analogous, not
homologous. The pseudopetioles found in some grasses are analogous, not homogolous, with the petioles of ordinary leaves.
Plants that produce flowers. The flowers of some plants have conspicuous colorful petals. In the Poaceae and Cyperaceae (and several other flowering
plant families), the flowers are inconspicuous. Angiosperms produce seeds that
are enclosed in an ovary.
The family of flowering
plants that includes sunflowers, daisies, dahlias, and dandelions. Its
members have several small flowers or florets that have an inferiorovary and are sessile on a
A bristlelike stucture formed by one or more veins
that extend beyond the edge or from the back or base of a structure, usually a structure
that is part of the dispersal unit. In grasses, awns are
frequently associated with lemmas and, less frequently, with glumes and paleas.
A type of wetland that is fed by precipitation; typically is acidic and nutrient poor; supporting plants adapted to low nitrogen environments. Because of the nutrient poor environment, carnivorous plants are frequently present.
A hard, solid portion of tissue. Calluses often develop
on diaspores. Because calluses are dense, diaspores tend to land callus-first. This usually results in the seed landing with its embryonic root pointing downwards. This
gives the seedling a slight advantage in becoming established over those that
land with their embryonic roots pointing upwards. In grasses, a callus is often developed
at the base of a lemma or spikelet. They are frequently sharply pointed.
Perennial species that form dense clumps of stems or
culms. The term refers to the appearance of the plant above ground level.
Cespitose plants may have rhizomes, but the rhizomes are short and do not
connect the clumps. See also rhizomatous, soboliferous, pluricespitose.
Caespitose is an alternative spelling of cespitose.
The family of flowering
plants that have inflorescences composed of several small flowers that are
sessile on a common receptacle. The family has two scientific names, Asteraceae or Compositae. Examples of composites are dandelions, sunflowers, and daisies.
One of the whorls of bracts that
surround the stamens in most flowers. It is usually colorful. Corolla refers to
all the petals in a flower. Some flowers, such as those of
buttercups and roses, have a corolla composed of several
separate petals. In other other flowers, such as those of tomatoes and lilacs,
the corolla is composed of connate
petals. Some flowering plants, including members of the grass and sedge families (Poaceae and Cyperaceae, respectively), do not have petals.
Stems that bear one or more inflorescences and have
leaves with a basalsheath. Used mostly (in North America) in discussions of the grass and sedge families (Poaceae and Cyperaceae,
respectively). See innovation.
A herbaceous monocot plant family
comprised of approximately 100 genera and 5000 species worldwide (Goetghebeur 1998). Culm usually trigonous in cross section with three-ranked leaves with closed sheaths; with inconspicuous flowers that are subtended by a bract
generally known as a scale; perianth if present, is composed of bristles or a
scale that wholly or partly surrounds the ovary.
The dispersal unit of a plant. This is often the fruit,
but may be the fruit with various accessory structures. In grasses, the dispersal unit is often a floret or spikelet rather than just the caryopsis. In Carex, it is
the perigynium with the achene inside.
To break up or fall off naturally. In Carex, perygnia diarticulate from the floral axis at
maturity. In grasses, disarticulation may occur in below an inflorescence, below a pair of spikelets, below individual spikelets, or below the florets.
Removed from a given area, generally used when the removal is the result of human action, either direct or indirect; used to describe populations of species known to have been present in an area within historical times.
Wetlands with a continuous source of groundwater that
has relatively high concentrations of magnesium and calcium; because of the
magnesium and calcium salts, fens are alkaline to neutral. Compare with bogs.
The lower, often threadlike, part of a stamen. Anthers
are attached to the distal end of filaments. Together, a filament and anther form a stamen.
Wind-pollinated plants have stamens with long, flexible filaments and versatile anthers. Animal-pollinated plants usually have short, stiff flaments.
A geographic area, usually rather large, that contains a more or less uniform assemblage of plants; the boundaries between floristic provinces are not precise; see map within key for Takhtajan's floristic provinces of North America.
In most flowering
plants, a flower consists of a calyx, corolla, stamens and pistils and is the sexual reproductive structure. The corolla is often colorful and showy. Many species have
flowers that lack a corolla, or stamens, or pistils, or some combination of these structures. In Carex,
the perigynium is probably homologous with a calyx; in grasses, the lodicules are generally considered to be homologous with the calyx.
Plants in which the seeds are produced inside an ovary and fertilization involves two sperm nuclei, one to
fertilize the egg, the second to fertilize the polar nuclei. In most flowering plants, the ovary is surrounded by stamens, petals, and sepals.
The lowest pair of bracts in a
typical grass spikelet. They are often described as empty because they do not
have any structures in their axils. In some species, one or both glumes may be absent or highly reduced. See also pseudospikelets
A family of herbaceous flowering plants in which the leaves are
two-ranked, the flowering stems (culms) are round in cross section, and the
flowers are inconspicuous, being concealed between two bracts, the lemma and palea, and the fruit is a caryopsis.
Grasses constitute the fourth largest plant family in terms of number of species.
A cluster of flowers within a plant that may contain one to many flowers. There may be several inflorescences on a single plant. In the grass and sedge families (Poaceae and Cyperaceae,
respectively) the apparent inflorescences are, strictly speaking,
synflorescences. The primary inflorescence in the
grass family is the spikelet; in the sedge family it is the spike. In most
references however, the term inflorescence is used for the synflorescence.
One of two bracts that enclose the
reproductive structures (lodicules, stamens, and pistil) of grasses, the other being the palea.
The lemma is the lower, and usually the larger, of
the two bracts. It usually has an odd number of veins. Lemmas may also be sterile and lack a palea and lodicules.
In the grass and sedge families (Poaceae and Cyperaceae,
respectively), tissue or hairs at the junction of the sheath and the blade. Almost all members
of both families have a ligule on the adaxial or inner side of the leaf; some bamboos also have
ligules on the abaxial side of the leaf. In sedges, the
ligule is usually hyaline to membranous.
Very small structures in grasses
that are located outside the stamens. The lodicules are homologous with the calyx and/or corolla of ordinary flowers. Grasses have two, three, or no lodicules. They are not used in identification but are significant in classification. At anthesis, they swell and help to spread open the lemma and palea.
Plants whose seeds and seedlings have only one seedling
leaf. Monocots also usually have a corolla and calyx that
consists of 3 parts or a multiple of 3, scattered vascular bundles in their
stems, and often have leaves with parallel venation. Grasses (Poaceae) and members of the sedge family (Cyperaceae) are monocots, as are lilies and orchids.
Plants that cannot grow in an area unless a particular
condition is met; obligate wetland species cannot grow
in dry habitats; obligate xeric species cannot grow in
wetland habitats. Many species of Carex are obligate
wetland species, they can only grow in wetlands. See facultative.
One of two bracts that enclose the
reproductive parts of a grass, the other being the lemma.
The palea is the upper of the two bracts and usually has two major veins. Additional veins may be present also.
One of the bracts that surrounds
the stamens in an ordinary flower. Petals are often colorful in visible light and often prominently marked in other invisible wavelengths; chiefly for the many pollinating insects that can see in ultaviolet light.
A term used for branches of the Andropogoneae in which the spikelets are in
sessile-pedicellate pairs, with disarticulation
being in the rame, beneath the sessile spikelet. The
pedicellate spikelet may be absent, vestigial, sterile, or staminate.
The basal part of a leaf that wraps
around the culm in grasses and
sedges. In grass leaves, the sheath is usually open - its margins may overlap but are not fused together. In Carex, the sheaths are closed - the margins are fused together for most of their length.