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POACEAE (Gramineae) GRASS FAMILY

James P. Smith, Jr., except as noted

Annual to woody perennial herb; roots generally fibrous. Stem: generally round, hollow; nodes swollen, solid. Leaf: alternate, 2-ranked, generally linear, parallel-veined; sheath generally open; ligule membranous or hairy, at blade base. Inflorescence: various (of generally many spikelets). Spikelet: glumes generally 2; florets (lemma, palea, flower) 1–many; lemma generally membranous, sometimes glume-like; palea generally ± transparent, ± enclosed by lemma. Flower: generally bisexual, minute; perianth vestigial; stamens generally 3; stigmas generally 2, generally plumose. Fruit: grain, sometimes achene- or utricle-like.
650–900 genera; ± 10550 species: worldwide; greatest economic importance of any family (wheat, rice, maize, millet, sorghum, sugar cane, forage crops, ornamental, weeds; thatching, weaving, building materials). [Barkworth et al. 2003 FNANM:25; Barkworth et al. 2007 FNANM:24] Generally wind-pollinated. Achnatherum, Ampelodesmos, Hesperostipa, Nassella, Piptatherum, Piptochaetium, Ptilagrostis moved to Stipa; Elytrigia, Leymus, Pascopyrum, Pseudoroegneria, Taeniatherum to Elymus; Hierochloe to Anthoxanthum; Lolium, Vulpia to Festuca; Lycurus to Muhlenbergia; Monanthochloe to Distichlis; Pleuraphis to Hilaria; Rhynchelytrum to Melinis. The following taxa (in genera not included here), recorded in California from historical collections or reported in literature, are extirpated, lacking vouchers, or not considered naturalized: Acrachne racemosa (Roth) Ohwi, Allolepis texana (Vasey) Soderstr. & H.F. Decker, Amphibromus nervosus (Hook. f.) Baill., Axonopus affinis Chase, Axonopus fissifolius (Raddi) Kuhlm., Coix lacryma-jobi L., Cutandia memphitica (Spreng.) K. Richt., Dinebra retroflexa (Vahl) Panz., Eremochloa ciliaris (L.) Merr., Eustachys distichophylla (Lag.) Nees, Gaudinia fragilis (L.) P. Beauv., Miscanthus sinensis Andersson, Neyraudia arundinacea (L.) Henrard, Phyllostachys aurea Rivière & C. Rivière, Phyllostachys bambusoides Siebold & Zuccarini, Rottboellia cochinchinensis (Lour.) Clayton, Schedonnardus paniculatus (Nutt.) Branner & Coville, Schizachyrium cirratum (Hack.) Wooton & Standl., Schizachyrium scoparium (Michx.) Nash, Themeda quadrivalvis (L.) Kuntze, Thysanolaena latifolia (Hornem.) Honda, Tribolium obliterum (Hemsl.) Renvoize, Zea mays L., Zizania palustris L. var. interior (Fassett) Dore, Zoysia japonica Steud. Paspalum pubiflorum E. Fourn., Paspalum quadrifarium Lam., are now reported for southern California (J Bot Res Inst Texas 4:761–770). See Glossary p. 30 for illustrations of general family characteristics. —Scientific Editors: James P. Smith, Jr., J. Travis Columbus, Dieter H. Wilken.
Unabridged references: [Hitchcock 1951 Manual grasses US, USDA Misc Publ 200; Clayton & Renvoise 1986 Kew Bull Add Series 13]

Key to Poaceae

POA BLUE GRASS

Robert J. Soreng

Annual, perennial herb; some ± dioecious. Stem: 0.3–12 dm. Leaf: sheath open most of length to closed (best observed on upper stem leaf); ligule thin, flexible, without a rim of hairs; blade grooved above on both sides of midvein, flat, folded, or inrolled, generally smooth or scabrous on veins, generally prow-tipped. Inflorescence: panicle-like; branches appressed to drooping. Spikelet: generally compressed, breaking between florets; glumes 2, ± equal, generally < lowest lemma, awnless; florets generally 2–6; callus indistinct, often with obvious tuft of long cobwebby hairs; lemma generally keeled to base, like glumes, awnless, veins generally 5, hairy or glabrous, upper margins thin-membranous; palea well developed, keel generally scabrous. Flower: generally bisexual, sometimes pistillate and/or staminate; fertile anthers 0.2–4.5 mm; ovary glabrous; fruit firm.
± 500 species: temperate and cool regions. (Greek: ancient name applied to various grasses, fodder plants) [Soreng 2007 FNANM 24:486–601] California is center of diversity in North America. Spikelet data recorded from lowest florets of spikelet at 25 ×.
Unabridged references: [Gillespie & Soreng 2005 Syst Bot 30:84–105; Soreng 1998 Novon 8:187–202; Soreng 1991 Syst Bot 16:507–528; Soreng 1991 Phytologia 71:340–413]

Key to Poa

P. cusickii Vasey
NATIVE
Perennial herb, ± densely cespitose, 1–6 dm; ± dioecious. Leaf: ligule generally 1–6 mm (on sterile stems < 2 mm, truncate, scabrous); blade longest at mid-stem, on sterile stems generally 0.5–1 mm wide, ± firm, inrolled (sometimes also folded), upper surface finely hairy. Inflorescence: lanceolate to ovate, generally dense; branches ascending to appressed, slender, smooth or scabrous. Spikelet: callus generally glabrous; lemma keeled, generally glabrous (rarely keel sparsely hairy), smooth or scabrous; palea keels scabrous. Flower: unisexual; fertile anthers 2–3.5 mm. [Online Interchange]

P. cusickii subsp. purpurascens (Vasey) Soreng
NATIVE
Leaf: basal tuft sparse; sheath open 1/4–1/2 length; 1–2 nodes exposed. Inflorescence: 4–8 cm, sparse; branches ascending, slender, sparsely scabrous, 17–30 cm, few-flowered. Spikelet: callus sometimes sparsely short-cobwebby; lemma 4.5–7 mm, keel, marginal veins generally sparsely short-hairy near base. Flower: pistillate only; fruit produced asexually.
2n=28. Moist subalpine meadows, ledges; 2100–3500 m. Klamath Ranges, n High Sierra Nevada; to British Columbia. [Poa alpina L. var. purpurascens Vasey; Poa purpurascens Vasey, illeg.] Jul–Sep [Online Interchange]

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Citation for the whole project: Jepson Flora Project (eds.) 2013. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on Dec 18 2014
Citation for this treatment: [Author of taxon treatment] 2013. Poa, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=52362, accessed on Dec 18 2014

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Geographic subdivisions indicated for the distribution of Poa cusickii subsp. purpurascens Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
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map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.