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Key to Fuirena

Cyperaceae

Fuirena

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1 Mature leaves broader, to ca. 1.5 cm wide; inflorescence a long, slender raceme, often with > 5 clusters of spikelet; plants tall, often > 1 m; [non-native; s. FL]
1 Mature leaves thinner (or reduced to sheath), typically < 1 cm wide; inflorescence terminal or racemose, typically with < 5 clusters of spikelet; plants shorter, < 1 m tall; [collectively widespread].
  2 Sheath of leaves glabrous, the largest leaf blade 0-2 (-5) cm long; plant strongly rhizomatous, the culm usually spaced about 10 cm apart.
    3 Blade of culm leaves < 5 cm long; spikelet mostly lance-ovoid, sessile in terminal clusters and also often with additional sessile or peduncled clusters lower on the culm; involucral bract longer than the spikelet
    3 Blade of culm leaves essentially reduced to sheath, or very short (< 0.5 cm long); spikelet mostly ovoid, sessile in terminal clusters; subtending involucral bract shorter than the spikelet
  2 Sheath of leaves sparsely to densely hirsute, the largest leaf blade 5-20 cm long; plant more-or-less cespitose, annual or perennial, if perennial the rhizome short and scaly or cormlike, the culm usually arising together.
      4 Perianth bristle no longer than the achene stipe (not nearly reaching halfway up the achene body), without barbs (sometimes very finely toothed, the teeth ascending); blade of the perianth scale with a blunt or short-apiculate apex
      4 Perianth bristle longer than the achene stipe, reaching the middle of or exceeding the achene body, strongly and retrorsely barbed (if smooth as in F. bushii, then scale of the spikelet also with strongly retrorse apical cusp); blade of the perianth scale with an acuminate to awned apex.
        5 Plants perennial, the rhizome scaly or elongate and slender; anther 0.9-1.3 mm long.
          6 Upper leaf sheath glabrous; perianth blade typically bearing a subapical bristle; perianth blade rounded or retuse, rarely acute; rhizome without corm-like buds
          6 Upper leaf sheath pubescent; perianth blade lacking a subapical bristle; rhizome with corm or corm-like buds or shoots present; perianth blade acute to acuminate.
             7 Perianth bristle retrorsely barbed, reaching perianth blade base or beyond; scale of the spikelet with 3-5 (-7) lower rib, the apical cusp 1/2-1x the length of the scale; [MA s. to FL, w. to c. TX]
             7 Perianth bristle mostly smooth and shorter than perianth blade; scale of the spikelet with 3 prominently raised medial rib, the apical cusp ≥ the length of the scale; [s. AR s. to LA, w. to se OK and e. TX]
        5 Plants annual, not bearing scaly rhizome; anther ca. 0.5 mm long.
               8 Blade of the perianth scale acuminate, narrowed into an awn (the awn without barbs)
               8 Blade of the perianth scale rounded, retuse, or rarely acute at the tip, bearing a subapical bristle which is retrorsely barbed