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Stigmas 3; achenes three-sided,
occasionally terete, though their shape may be concealed by flattened
perigynia; NOT [Stigmas 2; achenes lenticular] |
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Spikes 2 or more per culm, terminal and
lateral; spike bracts present on lateral spikes (except in Section Phyllostachyae), lowest bract usually evident, often conspicuous.
NOT [Spikes 1 per culm, terminal; spikes bracts absent] |
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Lower pistillate scales not bract-like or
leaf-like but similar in size and shape to individual perigynia (up to
twice as long as perigynia in C. magellanica ssp. irrigua]; NOT [Lower
pistillate scales resembling green, leaf-like bracts much longer and
wider than individual perigynia. Section Phyllostachyae] |
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Perigynia sparsely to densely pubescent
or puberulent (in C. pedunculata pubescence represented by very short
hairs scattered near tip; in some species of Sect. Acrocystis, perigynia
may be glabrous or virtually hairless, but all members of this group
have convexly 3-sided to terete achenes with tight-fitting perigynia and
a stipe-like base about equal to beak in length). NOT [perigynia
glabrous (i.e. lacking a pubescence)] |
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Perigynia usually less than 5 mm long but
if longer, beak distinctly shorter than perigynium body; pubescence
various. NOT [perigynia 5-7 mm long with beak as long as or longer than
perigynium body; pubescence on the perigynia dense, stiff and pointing
toward tip] |
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Achenes convexly 3-sided to terete;
perigynia tightly enclosing achenes and convexly 3-sided to terete,
sparsely pubescent, (rarely glabrous in C. deflexa and C.
rossii,
pubescent only on ribs in C. tonsa); stipe-like base about equal to beak
in length; pistillate spike bracts sheathless. Section Acrocystis.
NOT [Achenes with +/- flat sides; perigynia loosely fitting achene and
variously shaped in cross-section, densely to sparsely pubescent
(faintly puberulent with very short hairs scattered near tip in C.
pedunculata); pistillate spike bracts sheathing or sheathless] |
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All pistillate spikes cauline, i.e.
attached near top of regular, elongate culms and born at or above level
of leaf tips. NOT [Some or all pistillate spikes basal, i.e. attached
near base of plant and borne among leaf bases] |
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Staminate spike 10-20 mm long,
conspicuous above pistillate spikes; plants in dense tufts with copious
fibers on crown; leaves of vegetative shoots stiff, erect and nearly as
tall as inflorescence; plants of dry prairies. NOT [Staminate spike 3-10
mm long, inconspicuous among pistillate spikes; other features not as
above] |