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Poa annua

ANNUAL BLUE GRASS


Higher Taxonomy
Family: Poaceae (Gramineae)View DescriptionDichotomous Key
Common Name: GRASS FAMILY
Habit: 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.
Genera In Family: 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). Note: 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.
eFlora Treatment Author: James P. Smith, Jr., except as noted
Scientific Editor: James P. Smith, Jr., J. Travis Columbus, Dieter H. Wilken.
Genus: PoaView DescriptionDichotomous Key


Common Name: BLUE GRASS
Habit: 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.
Etymology: (Greek: ancient name applied to various grasses, fodder plants) Note: California is center of diversity in North America. Spikelet data recorded from lowest florets of spikelet at 25 ×.
eFlora Treatment Author: Robert J. Soreng
Reference: Soreng 2007 FNANM 24:486--601
Unabridged Reference: 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
Poa annua L.
NATURALIZED
Habit: Annual, biennial, cespitose or with stolons, 0.2--2 dm. Leaf: sheath open +- 2/3 length; ligule 1--5 mm, rounded to obtuse; blade generally 1--3 mm wide, soft, generally flat, bright- or yellow-green. Inflorescence: 1--10 cm, triangular, 1.2--1.6 × longer than wide, open in fruit; branches spreading, smooth, with spikelets only in top 1/2. Spikelet: axis +- hidden; callus glabrous; lemma 2.5--4 mm, smooth, veins soft-hairy or glabrous; palea keels hairy. Flower: bisexual or upper 1--2 pistillate; anther 0.6--1 mm. Chromosomes: 2n=28.
Ecology: Abundant. Disturbed moist ground; Elevation: generally < 2000 m. Bioregional Distribution: CA (esp near coast); Distribution Outside California: +- worldwide; native to Europe. Flowering Time: Feb--Sep
Jepson eFlora Author: Robert J. Soreng
Reference: Soreng 2007 FNANM 24:486--601
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)

Previous taxon: Poa abbreviata subsp. pattersonii
Next taxon: Poa atropurpurea

Botanical illustration including Poa annuabotanical illustration including Poa annua


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Citation for this treatment: Robert J. Soreng 2012, Poa annua, in Jepson Flora Project (eds.) Jepson eFlora, https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=38787, accessed on December 03, 2024.

Citation for the whole project: Jepson Flora Project (eds.) 2024, Jepson eFlora, https://ucjeps.berkeley.edu/eflora/, accessed on December 03, 2024.

Poa annua
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©2019 Neal Kramer
Poa annua
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©2019 Neal Kramer
Poa annua
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©2004 Carol W. Witham
Poa annua
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©2002 Julie Kierstead Nelson
Poa annua
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©2008 Keir Morse

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Geographic subdivisions for Poa annua:
CA (esp near coast)
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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 occurrence).






 

Data provided by the participants of the  Consortium of California Herbaria.

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Blue markers indicate specimens that map to one of the expected Jepson geographic subdivisions (see left map). Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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CCH collections by month Flowering-Fruiting Monthly Counts

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time (fruiting time in some monocot genera).