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  1. Family: Poaceae Barnhart
    1. Genus: Calamagrostis Adans.
      1. Calamagrostis tweedyi (Scribn.) Scribn.

        This species is accepted, and its native range is NW. U.S.A.

    [GB]
    Habit
    Perennial. Rhizomes short. Butt sheaths persistent and investing base of culm; with fibrous dead sheaths. Culms 60-150 cm long. Lateral branches lacking. Leaves basal and cauline. Ligule an eciliate membrane; 6-15 mm long; erose, or lacerate. Leaf-blades 5-20 cm long; 7-13 mm wide. Leaf-blade surface scabrous; rough adaxially.
    Inflorescences
    Inflorescence a panicle. Panicle contracted; linear, or lanceolate; continuous, or interrupted; 8-16 cm long; 2 cm wide. Spikelets solitary. Fertile spikelets pedicelled.
    Spikelets
    Spikelets comprising 1 fertile florets; with a barren rhachilla extension. Spikelets lanceolate; laterally compressed; 5.5-7 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus pubescent. Floret callus hairs 0.5-1 mm long; 0.1 length of lemma.
    Fertile
    Spikelets comprising 1 fertile florets; with a barren rhachilla extension. Spikelets lanceolate; laterally compressed; 5.5-7 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus pubescent. Floret callus hairs 0.5-1 mm long; 0.1 length of lemma.
    Glume
    Glumes persistent; similar; exceeding apex of florets; firmer than fertile lemma. Lower glume lanceolate; 1 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acute. Upper glume lanceolate; 5.5-7 mm long; 1.1 length of adjacent fertile lemma; membranous; 1-keeled; 1-3 -veined. Upper glume apex acute.
    Florets
    Fertile lemma lanceolate; 5-6.5 mm long; membranous; without keel; 5 -veined. Lemma surface scaberulous. Lemma apex dentate; 4 -fid; awned; 1 -awned. Principal lemma awn dorsal; arising 0.5 way up back of lemma; geniculate; 10-12 mm long overall; clearly exserted from spikelet; with twisted column. Palea 1 length of lemma. Rhachilla extension 2-4 mm long; villous.
    Flowers
    Lodicules 2; 1-1.5 mm long. Anthers 3; 4 mm long; purple. Stigmas 2.
    Fruits
    Caryopsis with adherent pericarp. Hilum punctiform. Disseminule comprising a floret.
    Distribution
    North America: northwest USA.
    Reference
    Aveneae. Fl Pac NW 1994.

    Distribution

    Native to:

    Idaho, Montana, Washington

    Synonyms

    Other Data

    Calamagrostis tweedyi (Scribn.) Scribn. appears in other Kew resources:

    Bibliography

    First published in Contr. U.S. Natl. Herb. 1: 249 (1892)

    Accepted by

    • Flora of North America Editorial Committee (2007). Flora of North America North of Mexico 24: 1-908. Oxford University Press, New York, Oxford.
    • Clayton, W.D., Harman, K.T. & Williamson, H. (2006). World Grass Species - Synonymy database The Board of Trustees of the Royal Botanic Gardens, Kew.

    Literature

    Kew Backbone Distributions

    • Flora of North America Editorial Committee (2007). Flora of North America North of Mexico 24: 1-908. Oxford University Press, New York, Oxford.

    Sources

    GrassBase - The Online World Grass Flora
    http://creativecommons.org/licenses/by-nc-sa/3.0

    Kew Backbone Distributions
    The International Plant Names Index and World Checklist of Selected Plant Families 2020. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
    © Copyright 2017 World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

    Kew Names and Taxonomic Backbone
    The International Plant Names Index and World Checklist of Selected Plant Families 2020. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
    © Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0