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swampforest beaksedge

Kunth's beaksedge

Habit Plants perennial, cespitose, to 100 cm; rhizomes sometimes produced, short, not stoloniferous. Plants solitary or in small tufts, (5–)10–70 cm, clonal; rhizomes strongly present, stoloniferous.
Culms

lax, erect to ascending-excurved, ± terete, leafy, slender, soft.

leafiest toward base, ± trigonous, slender.

Leaves

exceeded by inflorescence;

blades erect or ascending, linear, proximally flat, 2–4 mm wide, apex trigonous, subulate, tapering.

basal leaves spreadingascending, distal more erect, mostly exceeded by culms (except in highaltitude forms);

blades proximally flat or strongly folded, 1.5–4 mm wide, apex trigonous, subulate.

Inflorescences

spikelet clusters 4–6, widely spaced, loose, broadly to narrowly turbinate, paniculate, branches capillary, ultimate branches with 1 or 2 spikelets; leafy bracts exceeding proximal clusters, setaceous.

spikelet clusters (2–)3–5, compact, proximalmost widely spaced, turbinate to ovoid;

peduncles ascending;

branches ascending to spreading;

leaf bracts exceeding proximalmost clusters, exceeded by distal cluster.

Spikelets

solitary or in 2s, brown, ovoid, 2.5–3.5 mm;

fertile scales ovate, 1.5–2.2 mm, apex acute, apiculate.

deep redbrown to nearly black, ovoid, 3–4 mm, apex acute;

fertile scales ovate, 2.5–3 mm, apex acute, midrib included or shortexcurrent.

Flowers

perianth bristles 6, reaching tubercle base or slightly beyond, antrorsely barbellate.

perianth bristles 6, some short, some extending to or nearly to tubercle base, antrorsely barbellate.

Fruits

2–3 per spikelet, 1.5–1.6(–1.8) mm;

body brown or greenish, obovoid, lenticular, 1.1–1.2(–1.3) × 0.7–1 mm, margins narrow, distinct, sharp, flowing to tubercle;

surfaces finely transversely wavyrugulose, intervals of fine, nearly isodiametric or vertical-rectangular pitlike alveolae;

tubercle lowtriangular, entire, 0.3–0.4 mm.

2–3 per spikelet, 2–2.1 mm;

body pale yellowbrown, lenticular, broadly ellipsoidobovoid, 1.3–1.6 × 1–1.2 mm;

surfaces transversely irregularly rugulose, intervals with rows of vertical, narrowly rectangular alveolae;

tubercle evenly or concavely triangular, 0.5–0.6(–0.7) mm.

Rhynchospora decurrens

Rhynchospora kunthii

Phenology Fruiting late spring–summer. Fruiting late spring–summer.
Habitat Sandy alluvium of swamp forests and environs Marsh meadows, seeps, boggy sites
Elevation 0–100 m (0–300 ft) 1000–3500 m (3300–11500 ft)
Distribution
from FNA
AL; FL; GA; LA; MS; NC; SC
[BONAP county map]
from FNA
CA; Mexico; South America (Colombia)
[BONAP county map]
Discussion

Rhynchospora decurrens superficially resembles R. mixta, with which it is often associated in swamp forests. Its narrower fruit bodies with less distinct transverse rugosity; the smaller, more numerous rows of finer, pitlike alveolae; and its broader, lower tubercles with non-setose edges all comprise consistent differences. The name decurrens is apt, calling attention to the narrow, wirelike pale margins that extend from tubercle base to near the base of the fruit body.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 23, p. 226. FNA vol. 23, p. 225.
Parent taxa Cyperaceae > Rhynchospora Cyperaceae > Rhynchospora
Sibling taxa
R. alba, R. baldwinii, R. brachychaeta, R. breviseta, R. caduca, R. californica, R. capillacea, R. capitellata, R. careyana, R. cephalantha, R. chalarocephala, R. chapmanii, R. ciliaris, R. colorata, R. compressa, R. corniculata, R. crinipes, R. curtissii, R. debilis, R. divergens, R. elliottii, R. eximia, R. fascicularis, R. fernaldii, R. filifolia, R. floridensis, R. fusca, R. globularis, R. glomerata, R. gracilenta, R. grayi, R. harperi, R. harveyi, R. indianolensis, R. inexpansa, R. inundata, R. knieskernii, R. kunthii, R. latifolia, R. macra, R. macrostachya, R. megalocarpa, R. megaplumosa, R. microcarpa, R. microcephala, R. miliacea, R. mixta, R. nitens, R. nivea, R. odorata, R. oligantha, R. pallida, R. perplexa, R. pineticola, R. pleiantha, R. plumosa, R. punctata, R. pusilla, R. rariflora, R. recognita, R. scirpoides, R. solitaria, R. stenophylla, R. thornei, R. torreyana, R. tracyi, R. wrightiana
R. alba, R. baldwinii, R. brachychaeta, R. breviseta, R. caduca, R. californica, R. capillacea, R. capitellata, R. careyana, R. cephalantha, R. chalarocephala, R. chapmanii, R. ciliaris, R. colorata, R. compressa, R. corniculata, R. crinipes, R. curtissii, R. debilis, R. decurrens, R. divergens, R. elliottii, R. eximia, R. fascicularis, R. fernaldii, R. filifolia, R. floridensis, R. fusca, R. globularis, R. glomerata, R. gracilenta, R. grayi, R. harperi, R. harveyi, R. indianolensis, R. inexpansa, R. inundata, R. knieskernii, R. latifolia, R. macra, R. macrostachya, R. megalocarpa, R. megaplumosa, R. microcarpa, R. microcephala, R. miliacea, R. mixta, R. nitens, R. nivea, R. odorata, R. oligantha, R. pallida, R. perplexa, R. pineticola, R. pleiantha, R. plumosa, R. punctata, R. pusilla, R. rariflora, R. recognita, R. scirpoides, R. solitaria, R. stenophylla, R. thornei, R. torreyana, R. tracyi, R. wrightiana
Synonyms Phaeocephalum decurrens R. schaffneri
Name authority Chapman: Fl. South. U.S., 525. (1860) Nees ex Kunth: Enum. Pl. 2: 296. (1837)
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