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giant flatsedge, Mexican papyrus

pallid flatsedge

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

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

trigonous, (10–) 30–50(–80) cm × (0.8–)1–2 mm, glabrous or occasionally minutely scabridulous on distal angles.

Leaves

bladeless.

3–7, M- or V-shaped, (10–)25–40(–55) cm × 2–5 mm, margins and midribs scabridulous or glabrous.

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 3–6(–12), grayish to golden brown, loosely cylindric, (6–)10–20(–24) cm × (5–)8–11 mm;

rays 0 or 1–3, to 4 cm;

rachis glabrous;

bracts (3–)4–6(–8), horizontal to strongly reflexed, inversely W-shaped, (3–) 10–20(–30) cm × 1–5 mm;

rachilla deciduous, wings persistent, 0.3–0.5 mm wide.

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–)25–60(–100), spaced 1–2(–3) mm apart, broadly ellipsoid to oblong, ± terete, 2.4–3.6 × 0.8–1.2 mm;

distal spikelet spreading or ascending;

floral scales persistent, 1–2(–4), appressed, laterally golden brown to dull grayish white, frequently streaked with red, medially greenish, laterally 3–4-ribbed, medially 3-ribbed, oblong, 2.6–3.3 × 1.8–2.4 mm, apex broadly rounded.

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 0.6–0.8 mm;

styles 0.8–1.2(–1.4) mm;

stigmas 1.4–2 mm.

Achenes

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

reddish brown to dark brown, stipitate, ellipsoid, (1.6–)1.8–2(–2.2) × (0.6–)0.7–0.9 mm, base cuneate to ± attenuate, apex ± acute to broadly rounded, surfaces finely papillose to essentially glabrous.

Cyperus giganteus

Cyperus pallidicolor

Phenology Fruiting summer. Fruiting summer.
Habitat Stream banks, marshes Clearings in montane forests
Elevation 0–10 m (0–0 ft) 800–1200 m (2600–3900 ft)
Distribution
from FNA
LA; TX; Mexico; Central America; South America; West Indies [Introduced in North America]
[BONAP county map]
from FNA
AZ; NM; Mexico; Central America; South America
[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. 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. 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. 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. subambiguus var. pallidicolor
Name authority Vahl: Enum. Pl. 2: 364. (1805) (Kükenthal) G. C. Tucker: in R. McVaugh & W. R. Anderson, Fl. Novo-Galiciana 13: 324. (1993)
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