The World Flora Online

1. Pycreus flavescens (L.) Reichb., Fl. Germ. Excurs. 72 (1830).

Por C.D. Adams.

Cyperus flavescens L., Sp. Pl. 46 (1753). Tipo: Europa.

Anuales. Tallos 4-20(-30) cm, cespitosos, trígonos, lisos. Hojas pocas, a veces sin láminas; láminas cuando presentes hasta 20 cm x 0.5-2 mm, escabriúsculas en los márgenes y en la costilla media en el envés. Brácteas generalmente 2 o 3, hasta 12 cm, foliiformes. Rayos 1-4, hasta 3 cm. Espigas hasta 30 x 30 mm, laxamente ovoides. Espiguillas 1-8, 5-16 x 2-2.8 mm, oblongo-lanceoladas, fuertemente comprimidas, aproximadas en un raquis 3-6 mm, con 5-20(-30) flores; raquilla flexuosa, persistente, sin alas. Glumas 1.5-2.5 x 1.2-1.8 mm, ovadas, obtusas, deciduas, la costilla media verde, 2-3-nervia, 2-carinada proximalmente, los lados amarillentos o pardo-púrpura, enervios. Estambres 3. Estilo 0.4-1 mm. Aquenios 0.8-1.2 x 0.6-0.8 mm, obovoides, lenticulares, obtusos, apiculados, ligeramente estipitados, pardos o negros, los bordes convexos con un patrón superficial de células alargadas verticalmente en bandas transversas irregulares separadas por estrías levantadas. Pantanos abiertos, potreros, bordes de caminos. Ch, B-P. 0-2000 m. (Cosmopolita en algunos países templados y en muchos países tropicales.)

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Annual, or possibly caespitose perennial, 5-60 cm. Stem 0.5-1.5 mm diam., trigonous, obtusely trigonous below, smooth. Leaves shorter than stem; sheaths 20-50(100) mm, reddish-brown or brown, mouth margin slightly concave; blades up to 10 (-20) cm, (0.5-)1-2 mm wide, keeled or flat, grey-green, margins slightly involute, margins and midvein below scabrous, especially towards the acute apex. Inflorescence a globose cluster of spikes or a small anthelodium, primary branches up to 40 mm, cluster of spikes with c. 100 spikes, 15-30 mm diam.; bracts 2-3 foliose, up to 10(-20) cm; tubular prophyll brown. Spikes 5-15 x c. 2.5 mm, compressed, with up to 40 glumes; glume-like prophyll basally swollen; rachis quadrangular, almost straight, angles sharp, not winged, internodes c. 0.5 mm; glumes 2-2.5 mm, cymbiform, blunt mucronate, sides yellow-brown, margins scarious. Stamens 2. Nut 1-1.2 mm, globose or ellipsoid, stipitate, compressed, from yellow-brown to dark-brown, shiny, reticulate with areole twice as long as wide or more, lower ends of areole at same horizontal level, sometimes white protruding.

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Annual herb, up to 300 mm tall. Spikelets many in a dense head, branches few and short, yellowish.

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