Poa alpina - Michigan Natural Features Inventory - Michigan State ...

alpine bluegrass, Page 1 

Poa alpina L. alpine bluegrass 

Photo by Susan R. Crispin 

Status: State threatened 

Global and state rank: G5/S1S2 

Other common names: bluegrass 

Family: Poaceae (grass family), also known as the 

Gramineae 

Taxonomy: Alpine bluegrass has been divided into two 

subspecies, Poa alpina L. subsp. alpina, which is found 

through the range of the species, and P. alpina subsp. 

vivipara (L.) Arcang., which is known in Greenland, 

possibly Alaska, and commonly in Europe (Flora of 

North America 2007). 

Range: This circumboreal grass occurs south in eastern 

North America to Quebec, the Bruce Peninsula of 

Ontario, and Michigan’s Keweenaw Peninsula. In 

western North America it ranges south to Oregon and 

Colorado. It is considered rare in Newfoundland and 

Saskatchewan, and is known only from historical records 

in Nova Scotia (NatureServe 2007). 

State distribution: Alpine bluegrass is known from 21 

localities in the Upper Peninsula, with the vast majority 

of sites (16) occurring in Isle Royale National Park 

including the main island and several smaller islands 

within the archipelago, ranging up to Passage Island. 

Michigan Natural Features Inventory 

P.O. Box 30444 - Lansing, MI 48909-7944 

Phone: 517-373-1552 

Best Survey Period 

State Distribution 

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

The Passage Island occurrence was observed as 

consisting of hundreds of plants, while elsewhere within 

the park the populations were found to be much smaller 

and very local, comprised of about 20 to 100 plants. 

Two mainland records for the Keweenaw Peninsula 

localities are known only from pre-1900 collections, 

whereas two occurrences discovered on Manitou Island 

– located just east of the tip of the Keweenaw Peninsula 

– were documented in 1996 and 2005, respectively. 

Markedly disjunct from the western Lake Superior sites 

is a single occurrence in Chippewa County, comprised of 

about 50 plants discovered on the southern shoreline of 

Drummond Island in 1984. 

Recognition: Poa alpina grows in scattered, dense 

clumps with stems that range from about 1-4 dm tall, 

bearing primarily basal leaves that are 2-4 mm wide and 

usually one to two much reduced, upright stem leaves 

that are strongly boat-shaped at the tip. The stem is 

terminated by a pyramidal inflorescence which is ca. 

3-6 cm tall, at least half as wide and sometimes pinkish 

in color. In the spikelet, the lower part of the distinctly 

3-nerved lemma has long, fine hairs between the 

finely hairy keel and margins, and the base lacks a 

cobwebby tuft of hairs. The broadly ovate glumes are 

more than half as wide as long. The majority of 

Michigan’s Poa species can be distinguished by the 

presence of a distinct tuft of cobwebby hairs at the base 

of the lemma. Of the other four Poa species lacking a

cobwebby tuft at the lemma base, P. annua and P. 

autumnalis have five distinct lemma nerves, while P. 

compressa and P. canbyi have narrow inflorescences and 

lack long hairs between the keel and margin of the 

lemma. 

Best survey time/phenology: Most of the observations 

and collections of this species have occurred from early 

July through August, and flowering plants have been 

observed as early as mid-June. The optimal survey 

period for this species is thus estimated to be from mid- 

June through early September. 

FQI Coefficient and Wetland Category: 10, FACU 

Habitat: On Isle Royale’s shores, Poa alpina grows in 

basaltic rock crevices and along other wave-splashed, 

rocky shores where its associates include such species as 

Campanula rotundifolia (harebell), Potentilla tridentata 

(three-toothed cinquefoil), Trisetum spicatum (downy 

oatgrass), Euthamia graminifolia (grass-leaved 

goldenrod), Sagina nodosa (pearlwort), Polygonum 

viviparum (alpine bistort), Castilleja septentrionalis 

(pale Indian paintbrush), and Achillea millefolium 

(yarrow). On Passage Island it inhabits a disturbance 

opening and is concentrated along a footpath, growing in 

dense sod with Antennaria neglecta (pussytoes), 

Plantago major (common plantain), Fragaria 

virginiana (wild strawberry), and other native and 

adventive species. Although it thrives along rocky 

shores, alpine bluegrass may also occur along paths and 

elsewhere in interior areas under aspen and other 

overstory trees and or under shrubs such as Shepherdia 

canadensis (buffaloberry) and Physocarpus opulifolius 

(ninebark) or in open bearberry (Arctostaphylos uvaursi) 

– juniper (Juniperus spp.) heaths. Along the 

shoreline of Drummond Island, this species occurs on 

limestone in moist seepage areas with Trisetum spicatum 

and Carex scirpoidea (bulrush sedge). Elsewhere in its 

range it inhabits mostly calcareous subalpine and arctic 

habitats including alpine meadows, and also often occurs 

in disturbed ground (Flora of North America 2007). 

Biology: Alpine bluegrass is a tufted, low-growing 

perennial species. P. alpina subsp. vivipara, which is 

most common throughout northern and central Europe, 

is well known for its ability to reproduce asexually 

through the development of bulbiferous spikelets, 

producing spikelets that are either completely bulbiferous 

or those that are partly bulbiferous and partly flowering 



Phone: 517-373-1552 


(Flora of North America 2007). Producing vegetative 

bulbs or plantlets in place of seeds is a reproductive 

approach demonstrated by certain arctic/alpine grass 

species, and can be considered a conservation strategy 

for retaining genetic traits developed by stress tolerators 

in low nutrient habitats (Pierce et al. 2003). Pierce as 

well as Baxter and Farrar (1999) and Baxter et al. (1997) 

found through detailed experiments that Poa alpina var. 

vivipara (and possibly var. alpina) actually lost 

photosynthetic capacity through long-term growth under 

elevated CO 2 conditions. Their findings indicate that 

global climate change may adversely affect alpine 

bluegrass, although the research thus far appears to have 

focused primarily on one subspecies. 

Conservation/management: The majority of the 

Michigan stations for this species are contained within 

Isle Royale National Park, where there are few threats, 

although protection of these sites from excessive foot 

traffic and human alteration of adjacent inland 

communities is advised. Searches of the Keweenaw 

Peninsula shoreline should be continued to relocate 

historical mainland localities. Inventories are also 

warranted elsewhere throughout the Upper Peninsula to 

identify additional new populations in calcareous bedrock 

shoreline areas, as this somewhat obscure grass species 

may be overlooked. 

Comments: Poa ×gaspensis Fernald is a rare hybrid 

between P. alpina and P. pratensis subsp. alpigena 

(Lindm.) Hiitonen, known only from the coastal 

mountains of the Gaspé Peninsula in Quebec, Canada 

(Flora of North American 2007). Poa alpina ecotypes 

and their origin as glacial relics were examined in an 

extensive paper by Turesson (1927). 

Research needs: In addition to inventories, the 

conservation and management of this species would 

benefit from basic life history studies, including research 

on population structure and genetic diversity. 

Related abstracts: Volcanic bedrock lakeshore, smallflowered 

wood rush, alpine bistort, pearlwort, encrusted 

saxifrage, prickly saxifrage, rayless mountain ragwort, 

squashberry

Selected references: 

Baxter, R. and J.F. Farrar. 1999. Export of carbon from 

leaf blades of Poa alpina L. at elevated CO 2 and 

two nutrient regimes. J. Exp. Botany 50: 1215- 

1221. 

Baxter, R., T.W. Ashenden, and J.F. Farrar. 1997. 

Effect of elevated CO 2 and nutrient status on 

growth, dry matter partitioning and nutrient 

content of Poa alpina var. vivipara L. J. Exp. 

Botany 48: 1477-1486. 

Flora of North America Editorial Committee. 2007. 

Flora of North America, North of Mexico. 

Volume 24: Magnoliophyta: Commelinidae (in 

part): Poaceae, part 1. Oxford Univ. Press. 

New York, NY. 908 pp. 

Heide, O.M. 1989. Environmental control of flowering 

and viviparous proliferation in seminiferous and 

viviparous arctic populations of two Poa species. 

Arctic and Alpine Research 21: 305-315. 

NatureServe. 2007. NatureServe Explorer: an online 

encyclopedia of life [web application]. Version 

6.1. NatureServe, Arlington, Virginia. Available 

http://www.natureserve.org/explorer. (Accessed: 

October 15, 2007). 

Pierce, S., C.M. Stirling, and R. Baxter. 2003. 

Pseudoviviparous reproduction of Poa alpina var. 

vivipara L. (Poaceae) during long-term exposure 

to elevated atmospheric CO 2 . Annals of Botany 

91: 613-622. 

Turesson, G. 1927. Contributions to the genecology of 

glacial relics. Hereditar 9: 81-101. 

Schlag, R.N. and B. Erschbamer. Germination and 

establishment of seedlings on a glacier foreland in 

the Central Alps, Austria. Arctic, Antarctic, and 

Alpine Research 32: 270277. 

Solhaug, K.A. 1991. Long day stimulation of dry matter 

production in Poa alpina along a latitudinal 

gradient in Norway. Holarct. Ecol. 14: 161-168. 



Phone: 517-373-1552 

Abstract citation: 

This project was funded, in part, by: 

The Michigan Coastal Management Program, 

Michigan Department of Environmental Quality 

and the 


Penskar, M.R. 2008. Special Plant Abstract for Poa 

alpina (alpine bluegrass). Michigan Natural Features 

Inventory. Lansing, MI. 3 pp. 

Copyright 2008 Michigan State University Board of 

Trustees. 

Michigan State University Extension is an affirmativeaction, 

equal-opportunity organization. 

National Oceanic and Atmospheric Administration 

U.S. Department of Commerce

Poa alpina - Michigan Natural Features Inventory - Michigan State ...

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