National Collection of Imperiled Plants

CPC National Collection Plant Profile

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D. Lorence

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CPC National Collection Plant Profile

Poa mannii

Family:	Poaceae
Common Names:	Mann�s bluegrass, Mann's blue grass
Author:	Munro ex Hillebr.
Growth Habit:	Graminoid
CPC Number:	3538

Distribution
Protection
Conservation
References

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Photographer: D. Lorence
Image Owner: National Tropical Botanical Garden

Poa mannii is Not Sponsored

Primary custodian for this plant in the CPC National Collection of Endangered Plants is:

National Tropical Botanical Garden

Poa mannii

There are three endangered Poa species endemic to Hawai�i (U.S. Fish and Wildlife Service [USFWS] 2001), and all are found only on the island of Kauai. P. mannii, a member of the grass family (Poaceae) is a perennial grass with short rhizomes (underground stems) and erect, tufted culms (hollow or pithy stalks or stems).
P. mannii is distinguished from both P. siphonoglossa and P. sandvicensis by its fringed (with hair or bristles along margins) ligules and from P. sandvicensis by its shorter panicle branches. (USFWS 1995)

Little is known about the life history of P. mannii. Flowering cycles, pollination vectors, seed dispersal agents, longevity, specific environmental requirements, and limiting factors are unknown.

Distribution & Occurrence

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State Range

Hawaii

Habitat

P. mannii typically grows on cliffs, rock faces, or stream banks in lowland or montane wet, mesic. P. mannii can also be found in dry Metrosideros polymorpha (ohia) forests or Acacia koa (koa)-M. polymorpha montane mesic forest. They grow at elevations between 460 and 1,150 meters (1,510 and 3,770 ft).

Associated species of P. mannii include Chamaesyce celastroides var. hanapepensis (akoko), Artemisia australis (ahinahina), Bidens sandwicensis (kookoolau), Lobelia sandwicensis (no common name [NCN]), Wilkesia gymnoxiphium (iliau), Eragrostis variabilis (emoloa), Panicum lineale (NCN), Mariscus phloides (NCN), Luzula hawaiiensis (NCN), Carex meyenii (NCN), C. wahuensis (NCN), Cyrtandra wawrae (haiwale), Exocarpos luteolus (heau), Labordia helleri (kamakahala), Nototrichium sp. (kului), Hedyotis terminalis (manono), Melicope anisata (mokihana), M. barbigera (pelea), M. pallida (alani), Pouteria sandwicensis (alaa), Schiedea membranacea (NCN), Diospyros sandwicensis (lama), Psychotria mariniana (kopiko), P. greenwelliae (Kaua�i wild coffee), Kokia kauaiensis (kokio), Alectryon macrococcus (Hawai�i macrocossus), Antidesma platyphyllum (hame), Bidens cosmoides (poola ni), Dodonaea viscosa (aalii), and Schiedea amplexicaulis (NCN).

Distribution

P. mannii is endemic to Kaua�i and was historically found in Olokele Gulch. Today, they can be located in Kalalau Valley, Makaha Valley, Koaie Valley, and Waialae Valley (USFWS 2000).

Number Left

Number of Populations: 7 (USFWS 2001)
Number of Plants: 135 (USFWS 2001)

Protection

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Global Rank:	G1	11/10/1993	Guide to Global Ranks
Federal Status:	LE	11/10/1994	Guide to Federal Status
Recovery Plan:	Yes	9/20/1995

State/Area Protection

	State/Area	Rank	Status	Date
	Hawaii	S1		4/11/2002

Conservation, Ecology & Research

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Ecological Relationships

The breeding system of P. mannii is unknown. This species is wind-pollinated and their seeds are bird dispersed (Sakai et al. 1995).

Threats

Threats to P. mannii include habitat damage, trampling, and browsing by feral goats, and competition with invasive alien plants. Erigeron karvinskianus (daisy fleabane) has invaded Kalalau, Koaie, and Waialae Valleys, three of the areas where P. mannii occurs. Lantana camara (lantana) threatens all known populations, and Rubus argutus (Florida prickly blackberry) threatens the populations in Kalalau and Waialae Valleys. P. mannii is also threatened by fire, reduced reproductive vigor, and extinction from naturally occurring events, such as landslides or hurricanes (USFWS 2000).

P. mannii survives only in very steep areas that are inaccessible to goats, suggesting that goat herbivory may have eliminated this species from more accessible locations, as is the case for other rare plants from northwestern Kaua�i (USFWS 2002).

Current Research Summary

The National Seed Laboratory (NSSL) tested the seeds of P. mannii, finding that they are not recalcitrant and can tolerate freezing (Yoshinaga 2002).

Current Management Summary

A critical habitat designation has been proposed for P. mannii (USFWS 2002).

The National Tropical Botanical Garden (NTBG) currently has ex situ holdings of seeds in its seed bank, which represents two out of the seven populations. In addition, there are three plants that represent an additional population growing in the grounds of the botanical garden.

Research Management Needs

1. Secure all wild populations through sight management.
2. Conduct pollination biology studies.
3. Test the influence of weeding and fencing on populations of P. mannii.
4. Map genetic diversity in the surviving populations of P. mannii.
Recommendations derived from M.H. Chapin, M. Maunder, and USFWS (1995).

Ex Situ Needs

1. Establish secure ex situ stocks with full founder representation.
2. Develop proper horticultural protocols and pest management for P. mannii.
3. Survey ex situ holdings and conduct molecular fingerprinting.
Recommendations derived from M.H. Chapin and M. Maunder.

References

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Books (Single Authors)

Wagner, W.L.; Bruegmann, M.M.; Herbst, D.R; Lau, J.Q.C. 1999. Hawaiian Vascular Plants at Risk: 1999. Honolulu, HI: Bishop Museum Press Honolulu.

Wagner, W.L.; Herbst, D.R.; Sohmer, S.H. 1999. Manual of the flowering plants of Hawai'i--Revised Edition. Honolulu, HI: University of Hawaii Press and Bishop Museum Press. 1853p.

Books (Sections)

Kartesz, J.T. 1999. A synonymized checklist of the vascular flora of the U.S., Canada, and Greenland. In: Kartesz, J.T.; Meacham, C.A., editors. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden. Chapel Hill, NC.

Electronic Sources

NatureServe. (2008). NatureServe Explorer: An online encyclopedia of life [web application]. [Internet].Version 7.0. NatureServe, Arlington, Virginia. http://www.natureserve.org/explorer. Accessed: (June 17, 2008).

USFWS. (2001). Unpublished data. U.S. Fish and Wildlife Service, Honolulu, Hawaii 96817. Accessed: 2001.

Yoshinaga, A. (2002). Seed storage characteristics of Hawaiian species. [Web site] University of Hawaii, Honolulu, Hawaii 96848. http://www.hawaii.edu/scb/seed/seedtabl.html. Accessed: 2002.

Journal Articles

Hitchcock, A.S. 1922. The grasses of Hawaii. Memorandum of the Bernice P. Bishop Museum. 8: 101-230.

Sakai, A.K.; Wagner, W.L.; Ferguson, D.M.; Herbst, D.R. 1995. Origins of Dioecy in the Hawaiian Flora. Ecology. 76, 8: 2517-2529.

USFWS. 1993. Endangered Status for the Plant Poa mannii (Mann's bluegrass). Federal Register. 59, 217: 56330-56333.

USFWS. 1993. Proposed Endangered Status for the Plant Poa mannii (Mann's bluegrass). Federal Register. 58, 65: 18073-18077.

USFWS. 2000. Determinations of Whether Designation of Critical Habitat is Prudent for 81 Plants and Proposed Designations for 76 Plants From the Islands of Kauai and Niihau, Hawaii; [Proposed Rule]. Federal Register. 65, 216: 66807-66885.

USFWS. 2002. Revised Determinations of Prudency and Proposed Designations of Critical Habitat for Plant Species from the Islands of Kauai and Niihau, Hawaii. Federal Register. 67, 18: 3940-4098.

Reports

USFWS. 1995. Recovery Plan for the Kaua'i Plant Cluster. Portland, OR: U.S. Fish and Wildlife Service. p.270.

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This profile was updated on 3/4/2010