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Key to Rhynchospora
https://fsus.ncbg.unc.edu/main.php?pg=show-key.php&keyid=39690
2 Inflorescence bracts several, foliaceous, basally bright white, reflexed to horizontally spreading; [subgenus Diplostylae; section Dichromena] | |
2 Inflorescence bracts 0-several, capillary to foliaceous, green throughout (stramineous in age), variously oriented. | |
3 Bristles present, plumose (at least towards their bases); [subgenus Diplostylae; section Plumosae] | |
3 Bristles absent, or present and smooth or minutely barbed. | |
5 Achene surface smooth, minutely pitted, or finely striate (not ridged, rugose, or reticulate); [subgenus Diplostylae; sections Chapmaniae, Fasciculares, and Fuscae] | |
5 Achene surface transversely ridged, rugose, or honeycombed-reticulate (sometimes faintly so); [subgenus Diplostylae; sections Globulares, Harveyae, Mixtae, Psilocarya, Pusillae, and Rariflorae] |
Key to Rhynchospora, Key A: beaksedges with tubercles 3-23 mm long
[subgenus Haplostylae; sections Longirostres and Polycephalae]
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2 Spikelets arranged in subglobose, umbel-like clusters; achene margins crimped; plants not rhizomatous; [section Longirostres] |
2 Spikelets arranged in tightly globose clusters; achene margins not crimped; plants rhizomatous; [section Polycephalae] |
1 Spikelets in > 4 paniculate or corymbose clusters; tubercle 10-23 mm long; leaf blades 6-20 mm wide; [section Longirostres]. |
4 Plants rhizomatous; primary clusters with 1-6 loosely clustered spikelets; achene (3.5-) 4.0-4.8 mm long. |
Key to Rhynchospora, Key B: beaksedges with basally-white bracts (White-bracted Sedges) [subgenus Diplostylae; section Dichromena]
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1 Plant rhizomatous; achene+tubercle 1.5-2.0 mm long; [relatively widespread in our region, especially Coastal Plain from se. VA to s. FL and west to s. TX, but also rarely inland]. | |
Key to Rhynchospora, Key C: beaksedges with plumose bristles [subgenus Diplostylae; section Plumosae]
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1 Spikelets borne several to many in clusters, none of the spikelets on slender stalks; achene 1.3-2.2 mm long, 0.9-1.7 mm wide | |
5 Basal sheaths dull, light to medium brown; bristles shorter than the tubercle; bristles plumose in a basal zone that extends 40-90% of the length of the bristle, the terminal zone minutely denticulate (lacking a smooth middle zone); [widespread in the Atlantic and Gulf Coastal Plain from NC south to FL, west to TX] |
Key to Rhynchospora, Key D: beaksedges with bristles retrorsely barbed (at least distally)
or antrorsely barbed and straplike (flattened) [subgenus Diplostylae; section Albae]
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5 Clusters turbinate to hemispheric (rarely subglobose), the lowest spikelets usually spreading-ascending to spreading; larger leaves usually < 2 mm wide; achene 1.5-2.0 mm long; tubercle 1.0-1.6 mm long | |
6 Clusters 1-7, globose to hemispheric; achene 1.8-2.6 mm long, 1.1-1.8 mm wide; tubercle 1.4-2.4 mm long, shorter than to equaling body length. | |
11 Inflorescence typically with 1 terminal and 1 lateral cluster, the clusters ovoid, with 1-10 spikelets each; achene 1.8-2.0 mm long, 0.8-1.0 mm wide, 2-3 × as long as wide; leaves 0.2-0.4 mm wide | |
11 Inflorescence with 1-6 lateral clusters, the clusters turbinate with usually > 10 spikelets; achene 1.3-1.8 mm long, 0.9-1.2 mm wide, 1.5-2 × as long as wide; leaves 1.5-3.5 mm wide. | |
Key to Rhynchospora, Key E: beaksedges with bristles smooth, or antrorsely barbed and filiform,
or absent, the achene surface smooth, minutely pitted, or finely striate
[subgenus Diplostylae; sections Chapmaniae, Fasciculares, and Fuscae]
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4 Bristles absent or 1-3 rudimentary; scales white to pale tan (or pale reddish-brown in R. brachychaeta); [section Chapmaniae]. | |
5 Inflorescence composed of (1-) 2-3 turbinate to ellipsoid clusters; spikelets pale reddish-brown, (2.7-) 3-3.5 mm long; achenes usually 2 per spikelet | |
5 Inflorescence composed of 1 (-2) hemispheric to broadly turbinate cluster(s); spikelets white to pale brown, either 2-2.5 (-3) mm or (3.5-) 4-5.5 mm long; achenes 1 per spikelet. | |
8 Inflorescence of (1-) 2-4 (-10) clusters; tubercle 0.4-1.4 mm long, the margin setose; [section Fuscae]. | |
11 Leaves to 1.5 (-2) mm wide; achene 1.0-1.7 mm long, 0.9-1.1 mm wide; tubercle 0.5-1.5 mm long, triangular-subulate, the margins typically conspicuously concave. | |
12 Culms solitary to loosely cespitose by slender rhizomes; terminal internode straight; clusters turbinate to ovoid; achene 1.0-1.3 mm long, uniformly medium to dark brown; tubercle 0.7-1.5 mm long; bristles usually of two lengths, some equaling the tubercle, and some equaling or shorter than the achene | |
12 Culms solitary to cespitose, without slender rhizomes; terminal internode often arched; clusters corymbose to hemispheric; achene 1.3-1.7 mm long, pale to reddish-brown, often translucent centrally, with a distinctly thickened wire-like margin; tubercle 0.5-1.0 mm long; all bristles more-or-less equaling the tubercle | |
13 Plants without rhizomes; spikelets 2.5-5 mm long; achene translucent centrally; tubercle 0.4-0.7 mm long. | |
15 Achene 1.3-4.2 mm long, 1.1-3.6 mm wide, brown to dark brown. | |
16 Achene 2.0-4.2 mm long, 2.0-3.6 mm wide. | |
16 Achene 1.3-2.0 mm long, 1.1-1.7 mm wide. | |
20 Larger leaves to 1 mm wide; mature culms to 4.5 dm long; floral fascicles 1 (-2); tubercle 0.2-0.5 mm long | |
20 Larger leaves 2-4 mm wide; mature culms to 13 dm long; floral fascicles (1-) 2-4; tubercle 0.4-0.7 mm long | |
19 Bristles > ½ as long to exceeding the achene body. | |
21 Basal leaves 1.3-4 mm wide, all much shorter than the culm; tubercle triangular to triangular-attenuate. | |
22 Longer bristles < ½ as long to exceeding achene body; achene suborbicular, 1.2-1.5 mm wide; tubercle triangular; larger basal leaves 2-4 mm wide |
Key to Rhynchospora, Key F: beaksedges with bristles smooth, or antrorsely barbed and filiform, or absent,
the achene surface transversely ridged, rugose, or honeycombed-reticulate
[subgenus Diplostylae; sections Globulares, Harveyae, Mixtae, Psilocarya, Pusillae, Rariflorae]
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1 Bristles present or absent; if absent, then the achene > 1 mm long or > 0.7 mm wide, and tubercle triangular to subulate. | |
5 Achene including tubercle 1.5-2.9 mm long; tubercle triangular to triangular-acuminate; [section Rariflorae]. | |
4 Culms stouter; leaves wider, not filiform. | |
15 Culms 20-50 cm long; leaves 1-2 mm wide; bristles ½ or less as long as achene body | |
15 Culms 50-110 cm long; leaves (1-) 2-4.5 mm wide; longer bristles more than ½ as long to exceeding achene body. | |
16 Achene 0.8-1.4 mm long, 0.7-1.2 mm wide, the faces slightly biconvex with 6-12 transverse ridges. | |
18 Achene 1.4-4.2 mm long, 1.2-3.6 mm wide, the summit with a thickened bony to crustaceous rim surrounding the base of the tubercle; [section Harveyae]. | |
19 Achene tumid, lightly pitted or cancellate in a honeycomb pattern, 1.5-4.2 mm long, 1.4-3.6 mm wide. | |
20 Leaves 2-4 mm wide; achene < 2.7 mm long and < 2.5 mm wide. | |
24 Spikelets 4-6 (-8) mm long, dark brown to black, with an acute tip; tubercle ends accrescent to the achene | |
22 Bristles present (occasionally detached in R. decurrens and R. miliacea with achenes 1.0-1.4 mm long); achene 0.8-1.9 mm long. | |
29 Leaves to 2 mm wide; longer bristles no more than ½ as long as achene; achene body lenticular, one side often flattened | |
31 Longer bristles ⅓-½ (-¾)× the length of the achene; achene surface alveoli longitudinally narrow (typically 0.02-0.05 mm wide between the longitudinal walls), the latitudinal walls raised into horizontal ridges; tubercle 0.2-0.4 mm long, the base 0.5-0.7 mm wide | |
31 Longer bristles ⅔-1× the length of the achene; achene surface alveoli nearly as wide as long (typically 0.05-0.1 mm wide between the longitudinal walls), the latitudinal walls obscurely or not at all raised into horizontal ridges; tubercle 0.35-0.7 mm long, the base 0.7-0.9 mm wide | |
25 Bristles equaling or longer than the tubercle. | |
32 Primary branches of the inflorescence spreading at right angles from the culm, each spikelet or small cluster on slender spreading or reflexed stalks; [section Mixtae] | |
35 Achene obovate to suborbicular, 1.2-1.6 mm wide, latitudinal alveoli walls strongly raised into transverse ridges | |
35 Achene slenderly obovoid, 0.8-1.0 mm wide, latitudinal alveoli walls weakly or not at all raised into transverse ridges | |