Rhynchospora compressa
Rhynchospora gracilenta
flatfruit beaksedge
slender beaksedge
erect to ascending, leafiest at base, triangular, slender, somewhat stiff.
mostly lax, ascending to leaningexcurved, leafy, linear to filiform, terete.
exceeded by culm;
basal blades crowded, spreadingexcurved, distal ascending, linear, proximally flat, 3–5 mm wide, apex trigonous, shortsubulate.
shorter than culm;
blades ascending, filiform to narrowly linear, proximally flat, 0.5–1.5(–2.5) mm wide, margins distally strongly involute, apex trigonous, tapering.
spikelet clusters 3–5, compact, the proximalmost widely spaced, turbinate or lobed to hemispheric; leafy bracts setaceous, mostly overtopping clusters.
spikelet clusters 1–3(–4), proximalmost distant, dense to sparse, narrowly turbinate to hemispheric;
peduncles and branches ascending; leafy bracts linearsetaceous, mostly overtopping clusters.
redbrown, broadly ovoid, 3–3.5(–4) mm, apex acuminate;
fertile scales broadly ovate to ± orbiculate, 2–2.5(–3) mm, apex rounded to notched, midrib included or shortexcurrent.
redbrown, ovoid to lanceoloid, (3.5–)4–5 mm, apex acute;
fertile scales ovate, 3–4.5 mm, apex acute, mucronate to awnedcuspidate.
perianth bristles 6, reaching from fruit midbody to tubercle, antrorsely barbellate.
bristles 6, mostly reaching tip of tubercle or beyond, antrorsely barbellate.
1–2 per spikelet, (2–)2.5–2.8(–3) mm;
body brownish, broadly obovoid to nearly orbicular, 1.5–2 × 1.5–2 mm;
surfaces strongly transversely wavyrugose, intervals rows of vertical, rectangular alveolae;
tubercle conic-subulate, basal rim flaring above short neck on achene.
1–3 per spikelet, (2.5–)3–3.5(–4.1) mm;
body dark brown with small pale center, lenticular, broadly ellipsoid to suborbicular, 1.3–2.1 × 1.3–1.5 mm, smooth, margins narrow, flowing into tubercle;
tubercle triangular-subulate, compressed, mostly 1.5–2 mm.
Rhynchospora compressa
Rhynchospora gracilenta
Rhynchospora compressa is very closely akin to R. recognita and even coarser; inflorescence clusters are about as bristly and fertile scales blunter than those in R. recognita. It is less inclined to have an excurrent midrib, and the fruit is flatter. Both species often produce sterile spikelets, sometimes comprising an entire inflorescence.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Through the southern coastal plain are widerleaved examples of Rhynchospora gracilenta that are sparingly cespitose to solitary-stemmed, often with but a single terminal inflorescence with dense clusters of spikelets (var. diversifolia). That would be a tenable designation were it not for the large numbers of populations with intermediate habit.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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