A Key to the Sedges of the Valley of Cuatrocienegas, Coahuila, Mexico

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by Jack Siegrist

Note that this key does not include species that are found only in the surrounding mountains.

1a  Leaves absent:  2

      2a  Spikelets ovoid and few:

            3a  1 to 4 large ovoid spikelets at tip; plant to 60cm (2 feet) tall: Fuirena simplex

            3b  Only 1 ovoid spikelet at tip; plant to 40cm (16 inches) tall:

                  Eleocharis caribaea

      2b  Spikelet not ovoid, or if ovoid, there are many spikelets: 4

      4a  Stems circular, to 120cm (4 feet) tall from rhizomes; single spikelet:

            Eleocharis cellulosa

      4b  Stems compressed near the tips, 40cm to 100cm (16 to 40 inches) tall in tufts;

            multiple spikelets: Eleocharis rostellata

1b  Leaves present:  5

      5a  Inflorescence complex and open or bushy: 6

            6a  Plant 120cm to 300cm (4 to 10 feet) tall: Cladium jamaicense

            6b  Plant less than 120cm (4 feet) tall: 7

                  7a  Spikelets distributed pinnately on an elongate rachis; annual 4cm to 40cm (1.5 to 16 inches) tall: Cyperus odoratus

                  7b  Inflorescence compound umbels with spikelets on branched tips; plant to 120cm (4 feet) tall: Fimbristylis thermalis

      5b  Inflorescence simple or compact: 8

            8a  Inflorescences several long, compact spikes: Carex pringlei

            8b  Inflorescence not a spike: 9

                  9a  Inflorescence subtended by long, white, leaf-like bracts with green tips:

                        Dichromena colorata

                  9b  Inflorescence with bracts otherwise: 10

                        10a      Bracts 1 to 2, one to 8cm (3 inches) long: Schoenus nigricans

                        10b Bracts 3 to 5, one erect to 30cm (12 inches) long; inflorescence 3-20

                               spikelets: Scirpus maritimus

                        10c One bract, erect, appearing to be a continuation of the stem, making

                               the terminal inflorescence of 1-5 spikelets in a single cluster appear to

                               be in the middle of the stem: Scirpus olneyi

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