Pacific Island Ecosystems at Risk (PIER)


Pennisetum petiolare


RISK ASSESSMENT RESULTS: High risk, score: 7


Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i.
Information on Risk Assessments
Original risk assessment

Pennisetum petiolare (Hochst.) Chiov. Family - Poaceae. Common Names(s) - petioled fountaingrass - Synonym(s) - Beckera petiolaris (Hochst.) Hochst; Beckeropsis petiolaris (Hochst.).

Answer

Score

1.01

Is the species highly domesticated?

y=-3, n=0

n

0

1.02

Has the species become naturalized where grown?

y=1, n=-1

1.03

Does the species have weedy races?

y=-1, n=-1

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

2

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

2

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

1

2.05

Does the species have a history of repeated introductions outside its natural range?

y=-2, ?=-1, n=0

n

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

n

0

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

n

0

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n=0

n

0

3.04

Environmental weed y = 2*multiplier (see Append 2)

n=0

n

0

3.05

Congeneric weed y = 1*multiplier (see Append 2)

n=0

y

2

4.01

Produces spines, thorns or burrs

y=1, n=0

n

0

4.02

Allelopathic

y=1, n=0

4.03

Parasitic

y=1, n=0

n

0

4.04

Unpalatable to grazing animals

y=1, n=-1

n

-1

4.05

Toxic to animals

y=1, n=0

n

0

4.06

Host for recognized pests and pathogens

y=1, n=0

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

4.09

Is a shade tolerant plant at some stage of its life cycle

y=1, n=0

4.1

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

y=1, n=0

4.11

Climbing or smothering growth habit

y=1, n=0

n

0

4.12

Forms dense thickets

y=1, n=0

n

0

5.01

Aquatic

y=5, n=0

n

0

5.02

Grass

y=1, n=0

y

1

5.03

Nitrogen fixing woody plant

y=1, n=0

n

0

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

y=1, n=0

n

0

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

0

6.02

Produces viable seed.

y=1, n=-1

y

1

6.03

Hybridizes naturally

y=1, n=-1

6.04

Self-compatible or apomictic

y=1, n=-1

y

1

6.05

Requires specialist pollinators

y=-1, n=0

n

0

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

n

-1

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

See left

1

1

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y=1, n=-1

y

1

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

1

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

y

1

7.04

Propagules adapted to wind dispersal

y=1, n=-1

y

1

7.05

Propagules water dispersed

y=1, n=-1

n

-1

7.06

Propagules bird dispersed

y=1, n=-1

n

-1

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

7.08

Propagules survive passage through the gut

y=1, n=-1

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y=1, n=-1

8.03

Well controlled by herbicides

y=-1, n=1

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y=1, n=-1

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

y=-1, n=1

Total score:

7

Supporting data:

Notes

Source

1.01

No evidence

1.02

1.03

2.01

(1)DISTRIBUTION Africa: northeast tropical. (2)Pennisetum petiolare is native to northern Africa, where it grows in disturbed habitats. (2)To determine annual litter production of regenerating forest areas in the Tigray highlands of northern Ethiopia monthly litter production was monitored over a two-year period in areas with varying degree of vegetation cover restoration...The study area is located in the Dogu’a Tembien (Tembien highlands) district in Central Tigray, Ethiopia, near the district capital Hagere Selam (138390N, 398100E, altitude 2650 m a.s.l.)...The grazing lands are degraded areas where overgrazing has led to the disappearance of most vegetation so that severe soil erosion is taking place, removing nearly all fertile soil. In the rainy season, a grassy vegetation still develops, but shrubs and trees are scarce and small...Grasses include Chloris gayana Kunth., Cymbopogon caesius (Nees) Stapf., Cynodon dactylon (L.) Pers., Pennisetum petiolare (Hochst.) Chiov., Themeda triandra Forssk. [Study indicates Pennisetum petiolare grows in degraded, high elevation sites in Ethiopia]

(1)Clayton, W.D., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. http://www.kew.org/data/grasses-db.html. [accessed 17 April 2008]. (2)http://herbarium.usu.edu/treatments/Pennisetum.htm#Pennisetum_petiolare [Accessed 17 April 2008] (3)Descheemaeker, K., B. Muys, J. Nyssen, J. Poesen, D. Raes, M, Haile, J. Deckers. 2006. Litter production and organic matter accumulation in exclosures of the Tigray highlands, Ethiopia. Forest Ecology and Management 233(1): 21-35.

2.02

2.03

Unknown. (1)DISTRIBUTION Africa: northeast tropical. (2)Pennisetum petiolare is native to northern Africa, where it grows in disturbed habitats. (3)The study area is located in the Dogu’a Tembien (Tembien highlands) district in Central Tigray, Ethiopia, near the district capital Hagere Selam (138390N, 398100E, altitude 2650 m a.s.l.) [P. petiolare grows in study site, high elevation tropics]

(1)Clayton, W.D., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. http://www.kew.org/data/grasses-db.html. [accessed 17 April 2008]. (2)http://herbarium.usu.edu/treatments/Pennisetum.htm#Pennisetum_petiolare [Accessed 17 April 2008] (3)Descheemaeker, K., B. Muys, J. Nyssen, J. Poesen, D. Raes, M, Haile, J. Deckers. 2006. Litter production and organic matter accumulation in exclosures of the Tigray highlands, Ethiopia. Forest Ecology and Management 233(1): 21-35.

2.04

(1)DISTRIBUTION Africa: northeast tropical. (2)Pennisetum petiolare is native to northern Africa, where it grows in disturbed habitats. (2)To determine annual litter production of regenerating forest areas in the Tigray highlands of northern Ethiopia monthly litter production was monitored over a two-year period in areas with varying degree of vegetation cover restoration...The study area is located in the Dogu’a Tembien (Tembien highlands) district in Central Tigray, Ethiopia, near the district capital Hagere Selam (138390N, 398100E, altitude 2650 m a.s.l.)...The grazing lands are degraded areas where overgrazing has led to the disappearance of most vegetation so that severe soil erosion is taking place, removing nearly all fertile soil. In the rainy season, a grassy vegetation still develops, but shrubs and trees are scarce and small...Grasses include Chloris gayana Kunth., Cymbopogon caesius (Nees) Stapf., Cynodon dactylon (L.) Pers., Pennisetum petiolare (Hochst.) Chiov., Themeda triandra Forssk. [Study indicates Pennisetum petiolare grows in degraded, high elevation sites in Ethiopia]

(1)Clayton, W.D., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. http://www.kew.org/data/grasses-db.html. [accessed 17 April 2008]. (2)http://herbarium.usu.edu/treatments/Pennisetum.htm#Pennisetum_petiolare [Accessed 17 April 2008] (3)Descheemaeker, K., B. Muys, J. Nyssen, J. Poesen, D. Raes, M, Haile, J. Deckers. 2006. Litter production and organic matter accumulation in exclosures of the Tigray highlands, Ethiopia. Forest Ecology and Management 233(1): 21-35.

2.05

No evidence (1)Pennisetum petiolare is native to northern Africa, where it grows in disturbed habitats. The only collection in the Flora region is from Ames, Iowa, where it grew from fallen bird seed. It is not known to be established anywhere in the region.

(1)http://herbarium.usu.edu/treatments/Pennisetum.htm [Accessed 21 April 2008]

3.01

(1)Abstract: Pennisetum petiolare, a grass native to the Sudan and Ethiopia and never previously reported from North America, occurred in a lawn in Ames, Iowa. The source of the seed was contaminated Niger thistle (Guizotia abyssinica) seed used in a bird feeder directly above the location of the plant. The occurrence of at least 15 other seeds or fruits as contaminants in the sampe indicates that Niger thistle seed may serve as a medium for the introduction of weed seed into the United States [Insufficient evidence of naturalization] (2)Pennisetum petiolare is native to northern Africa, where it grows in disturbed habitats. The only collection in the Flora region is from Ames, Iowa, where it grew from fallen bird seed. It is not known to be established anywhere in the region.

(1)Pohl, R. W. 1987. PENNISETUM-PETIOLARE A PSEUDOPETIOLATE AFRICAN GRASS ADVENTIVE IN IOWA USA. Proceedings of the Iowa Academy of Science 94(1): 20-21. (2)http://herbarium.usu.edu/treatments/Pennisetum.htm#Pennisetum_petiolare [Accessed 17 April 2008]

3.02

(1)Table 2. List of known weed species not yet present in Australia that can be legally imported without any restriction because the genus they belong to is on Schedule 5 Permitted Seeds. Plant species and author are listed. [List includes Pennisetum petiolare without any information on weed status]

(1)Spafford Jacob, H, Randall, R, Lloyd, S. 2004. Front door wide open to weeds: an examination of the weed species permitted for import without risk assessment. WWF Australia.

3.03

(1)No evidence

(1)http://www.hear.org/gcw/species/pennisetum_petiolare/ [Accessed 21 April 2008]

3.04

(1)No evidence

(1)http://www.hear.org/gcw/species/pennisetum_petiolare/ [Accessed 21 April 2008]

3.05

(1)Five species of Pennisetum - P. setaceum, P. clandestinum, P. ciliare, P. polystachion and P. verticilliata are listed as invasive grasses.

(1)http://www.issg.org/database/species/search.asp?sts=sss&st=sss&fr=1&sn=Pennisetum&rn=&hci=-1&ei=-1&x=22&y=1

4.01

(1)Plants annual; tufted, rooting at the lower nodes. Culms 70-200 cm, slender, erect, branching; nodes glabrous. Sheaths glabrous; ligules 0.7-1 mm, of hairs; blades 3.5-30 cm long, 8-24 mm wide, flat, sparsely pubescent, abruptly rounded or cordate basally; lower blades with a 0.5-13 cm pseudopetiole. Panicles terminal and axillary, 3-8 cm, on long peduncles, fully exerted from the sheaths; rachises terete, hispid; disarticulation beneath the primary bristles, fascicle axes persistent. Fascicles 14-24 per cm; fascicle axes 0.4-0.6 mm, with 1 spikelet, outer and inner bristles absent; primary bristles 3.8-30 mm, scabrous. Spikelets 2.5-3.2 mm, sessile, green to purple. Glumes veinless, truncate or emarginate; lower glumes 0.2-0.3 mm; upper glumes 0.3-0.4 mm; lower florets sterile; lower lemmas 2.5-3.2 mm, strigulose above, 5-7-veined; lower paleas absent; upper lemmas 2.3-3 mm, sparsely puberulent, 5-veined; anthers 3, 1.5-1.9 mm. 2n = unknown.

(1)http://herbarium.usu.edu/treatments/Pennisetum.htm#Pennisetum_petiolare [Accessed 17 April 2008]

4.02

Unknown

4.03

No evidence

4.04

(1)The grazing lands are degraded areas where overgrazing has led to the disappearance of most vegetation so that severe soil erosion is taking place, removing nearly all fertile soil. In the rainy season, a grassy vegetation still develops, but shrubs and trees are scarce and small...The most obvious example is given by grasses, showing their biggest share of total litter production in the young exclosures of both study sites...Grasses include Chloris gayana Kunth., Cymbopogon caesius (Nees) Stapf., Cynodon dactylon (L.) Pers., Pennisetum petiolare (Hochst.) Chiov., Themeda triandra Forssk. [Study suggests that grasses, including P. petiolare, are palatable to grazing animals, and are the first to recover when exclosures are constructed]

(1)Descheemaeker, K., B. Muys, J. Nyssen, J. Poesen, D. Raes, M, Haile, J. Deckers. 2006. Litter production and organic matter accumulation in exclosures of the Tigray highlands, Ethiopia. Forest Ecology and Management 233(1): 21-35.

4.05

No evidence, but unlikely as species appears to be palatable to grazing animals.

 

4.06

Unknown

4.07

Unknown

4.08

Unknown

4.09

Unknown

4.1

Unknown

4.11

(1)Annual, tufted, slender, branched, rounded or cordate lower leaf blades abruptly contracted into a false petiole…

(1)Quattrocchi, U. 2006. CRC World Dictionary of Grasses: Common Names, Scientific Names, Eponyms, Synonyms, and Etymology - 3 Volumes. CRC Press, Boca Raton, FL.

4.12

(1)HABIT Annual. Culms erect; 45–120 cm long; compressible; with prop roots [unlikely that grass could impede movement, even if growing to maximum height]

(1)Clayton, W.D., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. http://www.kew.org/data/grasses-db.html. [accessed 17 April 2008].

5.01

Terrestrial

5.02

Poaceae

5.03

Poaceae

5.04

(1)Culms erect; 45–120 cm long; compressible; with prop roots.

(1)Clayton, W.D., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. http://www.kew.org/data/grasses-db.html. [accessed 17 April 2008].

6.01

No evidence

6.02

(1)Pennisetum petiolare is native to northern Africa, where it grows in disturbed habitats. The only collection in the Flora region is from Ames, Iowa, where it grew from fallen bird seed [Viable seed in contaminated bird seed]

(1)http://herbarium.usu.edu/webmanual/info2.asp?name=Pennisetum_purpureum&type=treatment [Accessed 17 April 2008]

6.03

Unknown [Intraspecific hybrids documented within genus Pennisetum] (1)Abstract: The study was undertaken at Punjab Agricultural University, Ludhiana, in 1991–1992 to investigate the behaviour of the pollen tubes of four wild Pennisetum species in the stigmatic tract of P. typhoides and to identify stages of pre-fertilization impediments to interspecific hybridization. Pollen germination was normal in crosses with P. violaceum, P. squamulatum and P. orientale and slightly inhibited in a cross with P. setaceum. Fertilization was accomplished within 3 h of pollination in a control cross within P. typhoides. P. typhoides × P. violaceum was a compatible cross and the pollen tubes of P. violaceum reached the ovary within 4 h of pollination. The presence of P. squamulatum and P. orientale pollen tubes in the ovary 10–15 h after pollination indicated the possibility of normal fertilization, while in crosses with P. setaceum, pollen tubes did not penetrate the ovary even 15 h after pollination. The study indicated that there is no impediment at the pollen germination stage or in the stigmatic hairy region. Delayed/restricted growth of pollen tubes indicated that the barrier operates in the styllar hairless region for the crosses with P. squamulatum and P. orientale, and at the ovarian level for the P. typhoides × P. setaceum cross.

(1)KAUSHAL, P. and J. S. SIDHU. 2000. Pre-fertilization incompatibility barriers to interspecific hybridizations in Pennisetum species. The Journal of Agricultural Science 134: 199-206

6.04

(1)all Pennisetum species are self-compatible.

(1)Reger, B.J. 1989. Stigma Surface Secretions of Pennisetum americanum. American Journal of Botany 76(1): 1-5.

6.05

Probably not - flower morphology does not reveal any adaptation to a specialist pollinator. Most grasses are wind-pollinated.

 

6.06

(1)Culms erect; 45–120 cm long; compressible; with prop roots. [No evidence, a bunch grass]

(1)Clayton, W.D., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. http://www.kew.org/data/grasses-db.html. [accessed 17 April 2008].

6.07

(1)Annual

(1)Quattrocchi, U. 2006. CRC World Dictionary of Grasses: Common Names, Scientific Names, Eponyms, Synonyms, and Etymology - 3 Volumes. CRC Press, Boca Raton, FL.

7.01

(1)Along roadsides, field margins, disturbed places.

(1)Quattrocchi, U. 2006. CRC World Dictionary of Grasses: Common Names, Scientific Names, Eponyms, Synonyms, and Etymology - 3 Volumes. CRC Press, Boca Raton, FL.

7.02

(1)These plants are ornamental gramineae

(1)http://www.gardening.eu/arc/plants/Shrubs/Pennisetum-petiolare-Hochst.-Chiov/50122/ [Accessed 21 April 2008]

7.03

(1)Abstract: Pennisetum petiolare, a grass native to the Sudan and Ethiopia and never previously reported from North America, occurred in a lawn in Ames, Iowa. The source of the seed was contaminated Niger thistle (Guizotia abyssinica) seed used in a bird feeder directly above the location of the plant. The occurrence of at least 15 other seeds or fruits as contaminants in the sampe indicates that Niger thistle seed may serve as a medium for the introduction of weed seed into the United States [Contaminant of bird seed]

(1)Pohl, R. W. 1987. PENNISETUM-PETIOLARE A PSEUDOPETIOLATE AFRICAN GRASS ADVENTIVE IN IOWA USA. Proceedings of the Iowa Academy of Science 94(1): 20-21.

7.04

(1)INFLORESCENCE Synflorescence compound; scanty. Inflorescence a panicle; terminal and axillary [Probably capable of short distance wind dispersal]

(1)Clayton, W.D., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. http://www.kew.org/data/grasses-db.html. [accessed 17 April 2008].

7.05

No evidence [Habitat and seed structure makes water dispersal unlikely]

 

7.06

No evidence

7.07

Possibly (1)Fertile spikelets sessile; 1 in the cluster. Involucre composed of bristles; base obtuse. Involucral bristles deciduous with the fertile spikelets; in one whorl [bristles could potentially get caught in fur/feathers]

(1)Clayton, W.D., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. http://www.kew.org/data/grasses-db.html. [accessed 17 April 2008].

7.08

[may be consumed incidentally during grazing, but no data on survival]

 

8.01

Unknown [no data on seed production, but unlikely to produce large seed quantities]

 

8.02

Unknown

8.03

Unknown

8.04

Unknown

8.05

Unknown


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