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giant flatsedge, Mexican papyrus

Piedmont flatsedge

Habit Herbs, perennial, rhizomatous, stout. Herbs, perennial, rhizomatous.
Culms

roundly trigonous, 200–350 cm × 15–50 mm, glabrous.

single or close together, trigonous, (10–)40–80(–120) cm × 1.2–2.5(–5) mm, glabrous.

Leaves

bladeless.

2–5, pleated, (10–)20–50(–90) cm × 2–5(–10) mm.

Inflorescences

spikes loosely cylindric, 15–40 × 8–16 mm;

rays 5–8, ascending to erect, stiff,20–30 cm; 2d order rays 5–15 cm;

bracts 10–12, ascending at 30–60°, flat, (8–) 20–45 cm × 4–12 mm; 2d order bracts (5–)15–25 cm × 1.5–5 mm;

rachilla persistent, separating laterally, remaining firmly attached basally, wings 0.3–0.4 mm wide.

spikes 1–4(–7), loose, broadly ovoid to ovoid-pyramidal, 25–35 × 25–35 mm;

rays (4–)5–6(–8), (1–)3–8(–16) cm, glabrous; 2d order rays (0–)1–5, 5–15(–50) mm;

bracts 4–7, ascending at 30–45°, pleated, (5–)20–40(–60) × (2–)3–8(–11) mm; 2d order bracts 1–4 per ray, 5–10(–30) × 0.5–1 mm, scabridulous;

rachilla persistent, wingless (or very narrowly winged, not clasping achene).

Spikelets

(15–)50–80, slightly compressed, linear, ± quadrangular, 5–12 × 0.6–1.4 mm;

floral scales 8–20, appressed, reddish beside 5-ribbed green medial part, white to hyaline near margins, ovate, 1.8–2.2 × 1.2–1.5 mm, apex acute to obtuse.

(10–)20–35(–45), seemingly flattened proximally from spreading floral scales, becoming terete apically, linear, (10–)13–18(–25) × 1.2–1.5(–1.6) mm;

floral scales deciduous, (10–)12–20(–25), laterally light reddish brown to dark red, medially greenish, laterally ribless, medially 3–5-ribbed, oblong-ovate, 1.7–2(–2.4) × 0.9–1.2 mm, apex obtuse, barely reaching next scale, apex entire, emarginate, mucro at most 0.3 mm.

Flowers

anthers 0.7–1 mm (connective prolonged beyond anther as red subulate appendage 0.2–0.5 mm, its apex sometimes setose);

styles 0.2–0.5 mm;

stigmas (0.8–)1.2–1.8 mm.

anthers 0.4–0.5 mm;

styles 0.3–0.6 mm;

stigmas 1–1.8(–2) mm.

Achenes

pale brown, sessile, oblong, 0.9–1 × 0.4–0.5 mm, apex scarcely apiculate, surfaces puncticulate.

dark brown, narrowly oblong, (1.3–)1.4–1.6(–1.7) × (0.3–)0.4–0.5 mm, base cuneate to ± stipelike, apex acute, not apiculate, surfaces papillose.

Cyperus giganteus

Cyperus distans

Phenology Fruiting summer. Fruiting summer.
Habitat Stream banks, marshes Marshes
Elevation 0–10 m (0–0 ft) 0 m (0 ft)
Distribution
from FNA
LA; TX; Mexico; Central America; South America; West Indies [Introduced in North America]
[BONAP county map]
from FNA
FL; NC; Mexico; South America; West Indies (Dominican Republic south through the Lesser Antilles); Asia; Africa
[BONAP county map]
Discussion

Cyperus giganteus was erroneously reported from Florida, a misidentification of C. papyrus (R. R. Haynes and A. Lasseigne 1969).

Recently, some nurseries specializing in water plants have begun to offer C. giganteus under the name “Mexican papyrus.” Escaped cultivated plants may be expected in southeastern and southwestern United States.

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

Source FNA vol. 23, p. 173. FNA vol. 23.
Parent taxa Cyperaceae > Cyperus > subg. Cyperus Cyperaceae > Cyperus > subg. Cyperus
Sibling taxa
C. acuminatus, C. aggregatus, C. alopecuroides, C. amabilis, C. articulatus, C. bipartitus, C. cephalanthus, C. compressus, C. croceus, C. cuspidatus, C. dentatus, C. dentoniae, C. diandrus, C. difformis, C. digitatus, C. dipsaceus, C. distans, C. distinctus, C. drummondii, C. echinatus, C. elegans, C. entrerianus, C. eragrostis, C. erythrorhizos, C. esculentus, C. fendlerianus, C. filicinus, C. filiculmis, C. filiformis, C. flavescens, C. flavicomus, C. floribundus, C. fugax, C. fuligineus, C. fuscus, C. gracilis, C. granitophilus, C. grayi, C. grayoides, C. haspan, C. hermaphroditus, C. houghtonii, C. hypopitys, C. hystricinus, C. involucratus, C. iria, C. laevigatus, C. lancastriensis, C. lanceolatus, C. lecontei, C. lentiginosus, C. ligularis, C. lupulinus, C. manimae, C. microiria, C. mutisii, C. niger, C. ochraceus, C. odoratus, C. onerosus, C. ovatus, C. owanii, C. oxylepis, C. pallidicolor, C. papyrus, C. parishii, C. pilosus, C. planifolius, C. plukenetii, C. polystachyos, C. prolifer, C. prolixus, C. pseudothyrsiflorus, C. pseudovegetus, C. pumilus, C. reflexus, C. refractus, C. retroflexus, C. retrofractus, C. retrorsus, C. rotundus, C. sanguinolentus, C. schweinitzii, C. serotinus, C. seslerioides, C. setigerus, C. spectabilis, C. sphacelatus, C. sphaerolepis, C. squarrosus, C. strigosus, C. surinamensis, C. tetragonus, C. thyrsiflorus, C. virens
C. acuminatus, C. aggregatus, C. alopecuroides, C. amabilis, C. articulatus, C. bipartitus, C. cephalanthus, C. compressus, C. croceus, C. cuspidatus, C. dentatus, C. dentoniae, C. diandrus, C. difformis, C. digitatus, C. dipsaceus, C. distinctus, C. drummondii, C. echinatus, C. elegans, C. entrerianus, C. eragrostis, C. erythrorhizos, C. esculentus, C. fendlerianus, C. filicinus, C. filiculmis, C. filiformis, C. flavescens, C. flavicomus, C. floribundus, C. fugax, C. fuligineus, C. fuscus, C. giganteus, C. gracilis, C. granitophilus, C. grayi, C. grayoides, C. haspan, C. hermaphroditus, C. houghtonii, C. hypopitys, C. hystricinus, C. involucratus, C. iria, C. laevigatus, C. lancastriensis, C. lanceolatus, C. lecontei, C. lentiginosus, C. ligularis, C. lupulinus, C. manimae, C. microiria, C. mutisii, C. niger, C. ochraceus, C. odoratus, C. onerosus, C. ovatus, C. owanii, C. oxylepis, C. pallidicolor, C. papyrus, C. parishii, C. pilosus, C. planifolius, C. plukenetii, C. polystachyos, C. prolifer, C. prolixus, C. pseudothyrsiflorus, C. pseudovegetus, C. pumilus, C. reflexus, C. refractus, C. retroflexus, C. retrofractus, C. retrorsus, C. rotundus, C. sanguinolentus, C. schweinitzii, C. serotinus, C. seslerioides, C. setigerus, C. spectabilis, C. sphacelatus, C. sphaerolepis, C. squarrosus, C. strigosus, C. surinamensis, C. tetragonus, C. thyrsiflorus, C. virens
Synonyms C. elatus
Name authority Vahl: Enum. Pl. 2: 364. (1805) Linnaeus f.: Suppl. Pl., 103. (1782)
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