Poa nemoralis
(wood bluegrass)

Pictures

Picture	Title	Caption	Copyright
Title Habit Caption Poa nemoralis (wood bluegrass); habit, growing beneath Quercus robur (English oak). Poland. Copyright ©Gil Wojciech/Polish Forest Research Institute/Bugwood.org - CC BY-NC 3.0 US	Habit	Poa nemoralis (wood bluegrass); habit, growing beneath Quercus robur (English oak). Poland.	©Gil Wojciech/Polish Forest Research Institute/Bugwood.org - CC BY-NC 3.0 US

Identity

Preferred Scientific Name

• Poa nemoralis L.

Preferred Common Name

• wood bluegrass

Other Scientific Names

• Agrostis alba L.
• Agrostis stolonifera f. alba (L.) Schur
• Agrostis vulgaris var. alba (L.) Gatt.
• Aira elodes Brign.
• Catabrosa elodes (Brign.) Roem. & Schult.
• Catabrosa helodes Roem. & Schult.
• Decandolia alba (L.) T. Bastard
• Eragrostis tenuis Steud.
• Festuca capitata Balb. ex Spreng.
• Festuca depauperata Bertol.
• Milium album (L.) Lag.
• Paneion nemorale (L.) Lunell
• Paneion nemorale L.
• Poa acmocalyx Keng f. & L.Liu
• Poa adjarica (Sommier & Levier) A.P.Khokhr.
• Poa alexeenkoi (Tzvelev) Czerep.
• Poa angustifolia var. nemoralis (L.) Huds.
• Poa asperula Steud.
• Poa balbisii Parl.
• Poa balfourii auct.
• Poa balfourii auct.
• Poa caespitosa Poir.
• Poa cinerea Vill.
• Poa coarctata Haller f. ex Gaudich.
• Poa debilis Thuill.
• Poa firmula (Gaudich.) Gray
• Poa glauca subsp. glaucantha (Gaudich.) Lindm.
• Poa glaucantha Schleich. ex Gaudin
• Poa glaucescens Roth
• Poa gracilescens Schrad.
• Poa hypanica Prokudin
• Poa juncea Suter
• Poa juncoides Gaudich.
• Poa korshunensis Golosk.
• Poa lapponica Prokudin
• Poa muralis Honck.
• Poa parnellii Bab.
• Poa pilipes Keng f. ex Shan Chen
• Poa polymorpha Wibel
• Poa pratensis var. cinerea (Vill.) Mathieu
• Poa pratensis var. fagetorum Rech. & T.C.Scheff.
• Poa scheuchzeri Suter
• Poa scopulorum Butters & Abbe
• Poa subpolaris Kuvaev
• Poa tenuis Clairv.
• Vilfa alba (L.) P.Beauv.

International Common Names

• English: woodland bluegrass

Local Common Names

• Canada: foin à vaches; forest bluegrass; pâturin des bois; woods bluegrass
• China: lin di zao shu he
• France: pâturin des bois
• Germany: Hainrispengras
• Italy: fienarola dei boschi
• Japan: tachi-ichigo-tsunagi
• Korea, Republic of: seonpoapul
• Russian Federation: mjatlik lesnoj
• Sweden: lundgröe
• UK: wood meadow grass
• USA: inland bluegrass

Summary of Invasiveness

Poa nemoralis, commonly known as wood bluegrass, is a perennial, densely-tufted grass which often grows in shaded places such as woodland. It is native to Eurasia and has been introduced to North America where it has become naturalized in some states and is considered invasive in Maine and potentially invasive in some forests in Wisconsin. Facilitating its spread is its ability to produce asexual seeds via apomixis, like other meadow grasses, and its use as a lawn grass.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Monocotyledonae
•                     Order: Cyperales
•                         Family: Poaceae
•                             Genus: Poa
•                                 Species: Poa nemoralis

Notes on Taxonomy and Nomenclature

Poa nemoralis L. is a grass species from the family Poaceae. Poa is Greek for fodder and nemoralis is Latin for growing in the woods. Hence its common name wood bluegrass. The Plant List (2013) lists 104 synonyms for this species.

In the PLANTS Database (USDA-NRCS, 2016) two subspecies are documented:  inland bluegrass (P. nemoralis  subsp. interior (Rydb.) W.A. Weber) which is considered native to North America, and wood bluegrass (P. nemoralis  subsp. nemoralis) which is introduced. However, this datasheet follows other treatments that accept P. interior Rydb. as a separate valid species (e.g. The Plant List, 2013).

There has been much debate over the boundary between mountain forms of P. nemoralis and non-glaucous forms of Poa glauca Vahl.. The form sometimes known as Poa balfourii Parn. is now included in P. glauca, not in P. nemoralis (Farmer, 2004).

Description

The following description is from Utah State University (2016):

Plants perennial; green or glaucous; densely tufted, not stoloniferous, not rhizomatous. Basal branching all or mostly extravaginal.

Culms 30-80 cm, mostly erect, smooth below the panicles; nodes slightly com-pressed, 2-5 exserted, top node at 1/2-3/4 the culm length.

Sheaths closed for 1/10-1/5 their length, terete, bases of basal sheaths glabrous, distal sheath lengths 0.45-1 (1.1) times blade lengths; ligules 0.2-0.8(1) mm, sparsely to densely scabrous, apices truncate, minutely ciliolate; blades 0.8-3 mm wide, mostly flat, appressed, abruptly ascending to spreading, straight or somewhat lax, apices narrowly prow-shaped.

Panicles 7-16(20) cm, lengths usually 2.5-4 times widths at maturity, usually erect, lax in shade forms, narrowly lanceoloid to ovoid, slightly to moderately congested; nodes with 2-5 b-anches; branches ascending to widely spreading, fairly straight, slender to moderately stout, angled, angles moderately to densely scabrous.

Spikelets 3-8 mm, lengths 2.5-3.5 times widths, narrowly lanceolate to lanceolate, laterally compressed, usually not glaucous; florets (1)2-5; rachilla internodes usually shorter than 1 mm, smooth, muriculate, or scabrous, usually puberulent, infrequently hispidulous or glabrous.

Glumes subulate to narrowly lanceolate, distinctly keeled, keels smooth or sparsely scabrous, apices sharply acute to acuminate; lower glumes 3-veined, long-tapered to a slender point, lengths 6.4-11 times widths; upper glumes shorter than or subequal to the lowest lemmas; calluses webbed, hairs sparse, often short; lemmas 2.4-4 mm, proximal lemma widths less than 1/5 times lengths, narrowly lanceolate to lanceolate, distinctly keeled, keels and marginal veins short-villous, lateral veins glabrous, obscure, intercostal regions smooth or muriculate, glabrous, margins glabrous, apices acute, usually partially bronze-colored; palea keels scabrous, intercostal regions glabrous; anthers 0.8-1.9 mm. Caryopses 1.5 mm long.

A description of P. nemoralis, along with photographs, is also given by Lind (2013).

Distribution

P. nemoralis is native to Eurasia (Gray, 1908; Royal Botanic Garden Edinburgh, 2016; USDA-ARS, 2016). It is widespread across Europe, from Portugal to Bulgaria (Royal Botanic Garden Edinburgh, 2016; USDA-ARS, 2016), and across Asia, from Iran to Japan (USDA-ARS, 2016). It is now common in southeastern Canada and the northeastern United States (USDA-NRCS, 2016). It has also been reported as naturalized in Australia and New Zealand (Council of Heads of Australasian Herbaria, 2016; USDA-ARS, 2016).

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

Introduced from Eurasia, it is now common in mixed woodlands of the northeastern United States and is spreading to the West (New England Wild Flower Society, 2016; Utah State University, 2016). Although an exact date of introduction cannot be found in Clark and Malte (1913) it is stated that seeds of P. nemoralis were mainly obtained from Germany.

Introductions

Risk of Introduction

It is probable that P. nemoralis will spread further due to its use to create lawns and playing fields (Watson and Dallwitz, 1992).

Habitat

In its native range P. nemoralis is mainly reported from woodlands and other shady places such as glades and hedgerows (Online Atlas of the British and Irish Flora, 2016). In its introduced range in North America is it is recorded from coniferous forests (Dibble et al., 2008), mixed woodlands, disturbed or man-made sites, floodplains and shores of rivers and lakes (New England Wild Flower Society, 2016).

Habitat List

Biology and Ecology

Genetics

Usually hexaploid. 2n = 42, but also 2n = 28, 35, 48, 50, 56 (Utah State University, 2016). Hubbard (1959) comments that it is a very variable species.

Reproductive Biology

P. nemoralis has been reported to shed pollen between 5-8 p.m. (Gibson, 2009).

It can produce asexual seeds via apomixis and can reproduce vegetatively (Asker and Jerling, 1992; Naumova et al., 1999).

Physiology and Phenology

P. nemoralis has C₃ physiology. In Norway, at Ås, 59º 40’ N, a minimum of two long days cycles was required for floral induction (Olam, 1986).

Longevity

Ryser and Urbas (2000) found the leaves of P. nemoralis to have an average life span of 39 days in their experiments.

Environmental Requirements

Good resistance to drought, shade and has good winter hardiness (Gibson, 2009).

Generally grows in lowland but can grow up to 915 m in altitude in Scotland, UK (Online Atlas of the British and Irish Flora, 2016).

It has been found on loam soil types in beech forests (Staaf et al., 1987).

Climate

Soil Tolerances

Soil texture

• medium

Means of Movement and Dispersal

Natural Dispersal

P. nemoralis produces seeds asexually (apomixis) which facilitates its spread, particularly long-distance (Asker and Jerling, 1992; Poschlod et al., 2003) (for more detailed information on apomixis in P. nemoralis see Naumova et al. (1999)). It can also reproduce vegetatively (another type of asexual reproduction) which facilitates more local spread (Asker and Jerling, 1992).

Accidental Introduction

Possibly introduced with wool shoddy, grass-seed or soil (Online Atlas of the British and Irish Flora, 2016).

Intentional Introduction

Introduced to provide grass cover (see Uses section).

Pathway Causes

Pathway Vectors

Impact Summary

Environmental Impact

A study by Dibble and Rees (2005) suggests that non-native plants have altered fuel characteristics in coniferous forests in southern Maine, USA; grasses such as P. nemoralis contribute to the fine-fuel load and may extend the period of fire threat under drought conditions.  

P. nemoralis is reported to be capable of becoming invasive in some forests in Wisconsin, USA (University of Wisconsin, 2016).

Risk and Impact Factors

• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Is a habitat generalist
• Pioneering in disturbed areas
• Tolerant of shade
• Has propagules that can remain viable for more than one year
• Reproduces asexually

• Modification of fire regime
• Threat to/ loss of native species

• Competition

• Difficult to identify/detect as a commodity contaminant

Uses

Economic Value

Sown in woodlands, parks, gardens and playing fields due to its ornamental value as a lawn or turfgrass (Watson and Dallwitz, 1992; Online Atlas of the British and Irish Flora, 2016).

Uses List

Animal feed, fodder, forage

• Fodder/animal feed

Environmental

• Ornamental

Similarities to Other Species/Conditions

Poa glauca and Poa interior are similar and can be distinguished from P. nemoralis by P. nemoralis’ consistently short ligules, high top culm node, relatively long flag leaf blades, and narrow glumes and lemmas (Utah State University, 2016).

Sometimes confused with Poa palustris which has ligules mostly 1.5-6 mm long and base of lemma with abundant soft, tangled hairs, versus P. nemoralis, with ligules mostly 0.2-0.7 mm long and base of lemma with sparse soft, tangled hairs (New England Wildflower Society, 2016).

Prevention and Control

No specific measures for controlling this grass species have been found.

References

Asker SE; Jerling L, 1992. Apomixis in Plants. Florida, USA: CRC Press, 320 pp.

Campbell J, 2016. Bluegrass Woodland: Kentucky plants. USA. http://www.bluegrasswoodland.com/Kentucky_Plants_Flora.html

Canadensys, 2016. Poa nemoralis. Canada. http://data.canadensys.net/vascan/name/Poa%20nemoralis

Clark GH; Malte MO, 1913. Fodder and Pasture Plants. Ottawa, Canada: Dominion of Canada Department of Agriculture, 143 pp.

Council of Heads of Australasian Herbaria, 2016. Australia's Virtual Herbarium., Australia: Council of Heads of Australasian Herbaria. http://avh.ala.org.au

Deakin R, 1857. Florigraphia Britannica; or Engravings and Descriptions of the Flowering Plants and Ferns of Britain. Vol I - Classes I to V. London, UK: Groombridge, 683 pp.

Dibble AC; Rees CA, 2005. Does the lack of reference ecosystems limit our science? A case study in nonnnative invasive plants as forest fuels. Journal of Forestry, 103(7):329-338. http://www.ingenta.com/journals/browse/saf/jof

Dibble AC; Zouhar K; Kapler Smith J, 2008. Fire and non-native invasive plants in the Northeast Bioregion. In: Wildland fire in ecosystems: fire and nonnative invasive plants. General Technical Report-GTR-42. Vol 6. USA: USDA-Forest Service. https://www.bia.gov/cs/groups/xnifc/documents/text/idc012449.pdf

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Farmer C, 2004. West Highland Flora. Scotland. http://www.plant-identification.co.uk/

Gibson DJ, 2009. Grasses and Grassland Ecology. Oxford, UK: Oxford University Press, 305 pp.

Gray A, 1908. Grey's New Manual of Botany: A Handbook of the Flowering Plants and Ferns of the Central and Northeastern United States and Adjacent Canada, Seventh edition [ed. by Robinson BL, Fernald ML]. Chicago, USA: American Book Company, 926 pp.

Harms VL, 2006. Annotated Catalogue of Saskatchewan Vascular Plants. 116 pp. http://www.biodiversity.sk.ca/Docs/AnnotatedCatalogueSKVascPlants2006.pdf

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Lind DW, 2013. French Hill Pond Field Plants: Wood Bluegrass (Poa nemoralis). Maine, USA. http://frenchhillpond.org/Pond/Flora/Field%20Plants/Wood%20Bluegrass%20(Poa%20nemoralis).htm

Maine Department of Agriculture; Conservation and Forestry, 2017. Maine Natural Areas Program: invasive plant fact sheets. http://www.maine.gov/dacf/mnap/features/invasive_plants/invsheets.htm

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University of Wisconsin, 2016. Herbarium - Cofrin Center for Biodiversity: Invasive Plants of Wisconsin. Poa nemoralis L. Wisconsin, USA: University of Wisconsin, Green Bay. http://www.uwgb.edu/biodiversity/herbarium/invasive_species/invasive_plants01.htm

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Links to Websites

Contributors

01/03/2016 Original text by:

Belinda Luke, CABI, UK

Distribution Maps