Pacific Island Ecosystems at Risk (PIER)

Pennisetum glaucum

RISK ASSESSMENT RESULTS: Low risk, score: 3 (low risk based on second screen)

Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i.
Information on Risk Assessments
Original risk assessment
  Pennisetum glaucum 'purple majesty' (pearl millet, bulrush, cattail millet, cat's tail grass, cattail millet, mongoose tail grass)  Synonym.: Setaria glauca,  Pennisetum typhoides (Burm.) Stapf & Hubb., Pennisetum americanum (L.) Leeke  Family- Poaceae Answer Score
1.01 Is the species highly domesticated? (If answer is 'no' then go to question 2.01) y -3
1.02 Has the species become naturalized where grown? n -1
1.03 Does the species have weedy races? 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
2.04 Native or naturalized in regions with tropical or subtropical climates y 1
2.05 Does the species have a history of repeated introductions outside its natural range?  y=-2 y  
3.01 Naturalized beyond native range         y = 1*multiplier (see Append 2), n= question 2.05 n -2
3.02 Garden/amenity/disturbance weed                              y = 1*multiplier (see Append 2) n 0
3.03 Agricultural/forestry/horticultural weed                         y = 2*multiplier (see Append 2) n 0
3.04 Environmental weed                                                     y = 2*multiplier (see Append 2) n 0
3.05 Congeneric weed                                                          y = 1*multiplier (see Append 2) y 2
4.01 Produces spines, thorns or burrs n 0
4.02 Allelopathic n 0
4.03 Parasitic n 0
4.04 Unpalatable to grazing animals    
4.05 Toxic to animals    
4.06 Host for recognized pests and pathogens n 0
4.07 Causes allergies or is otherwise toxic to humans n 0
4.08 Creates a fire hazard in natural ecosystems y 1
4.09 Is a shade tolerant plant at some stage of its life cycle n 0
4.1 Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island) y 1
4.11 Climbing or smothering growth habit n 0
4.12 Forms dense thickets n 0
5.01 Aquatic n 0
5.02 Grass y 1
5.03 Nitrogen fixing woody plant n 0
5.04 Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers) n 0
6.01 Evidence of substantial reproductive failure in native habitat n 0
6.02 Produces viable seed. y 1
6.03 Hybridizes naturally    
6.04 Self-compatible or apomictic y 1
6.05 Requires specialist pollinators n 0
6.06 Reproduction by vegetative fragmentation n -1
6.07 Minimum generative time (years)                 1 year = 1, 2 or 3 years = 0, 4+ years = -1 1 1
7.01 Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas) y 1
7.02 Propagules dispersed intentionally by people y 1
7.03 Propagules likely to disperse as a produce contaminant y 1
7.04 Propagules adapted to wind dispersal y 1
7.05 Propagules water dispersed n -1
7.06 Propagules bird dispersed n -1
7.07 Propagules dispersed by other animals (externally) n -1
7.08 Propagules survive passage through the gut n -1
8.01 Prolific seed production (>1000/m2) y 1
8.02 Evidence that a persistent propagule bank is formed (>1 yr) n -1
8.03 Well controlled by herbicides    
8.04 Tolerates, or benefits from, mutilation, cultivation, or fire n -1
8.05 Effective natural enemies present locally (e.g. introduced biocontrol agents)    
  Total score:   3
  Second screening result   Low risk

Supporting data:




(1)"Wild and cultivated pearl millet have a stikingly different plant architecture and spikelet structure. The wild form is characterised by abundant tillering and branching with short and thin spikes. Its spikelets have a short involucral pedicel length

(1)Genetic control of domestication traits in pearl millet (Pennisetum glaucum L., Poaceae) . By: Poncet, V.; Theoretical and Applied Genetics 100 (1), 2000, p.147-159 (Journal article) (2)


No evidence of naturalization


No evidence


(1)"Native range: "Warmer parts of the north temperate zone of the Old World, but now widely distributed in America, Australia, and the tropical areas of the Old World" (2)Purple majesty - "The plant is tropical in origin and likes warmth."

(1) (2)



USDA Zone 8a: to -12.2° C (10° F)
USDA Zone 8b: to -9.4° C (15° F)
USDA Zone 9a: to -6.6° C (20° F)
USDA Zone 9b: to -3.8° C (25° F)
USDA Zone 10a: to -1.1°C (30° F)
USDA Zone 10b: to 1.7° C (35° F)


(1)"Native range: "Warmer parts of the north temperate zone of the Old World, but now widely distributed in America, Australia, and the tropical areas of the Old World" (2)Purple majesty - "The plant is tropical in origin and likes warmth."

(1) (2)


(1)Pennisetum glaucum - "In non-traditional growing areas in the USA, Canada, Brazil, Australia, and Europe, pearl millet is grown as a forage, grain, or cover crop. Different varieties are grown for forage or grain." (2)Purple majesty - It originated in

(1) (2) (3) (4)


No evidence


No evidence


No evidence


No evidence - but - "May be a noxious weed or invasive."


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


No evidence


"A laboratory study was conducted to verify the allelopathic potential of aqueous extracts of wheat [Triticum aestivum], black oat [Avena nuda], pearl millet [Pennisetum glaucum], turnip [Brassica campestris var. rapa] and rape [B. napus var. oleifera] at

(1)Cover crop allelopathic potential in the development of corn seedlings . / Potencial alelopatico de cultivos de cobertura vegetal no desenvolvimento de plantulas de milho By: Tokura, L. K.; Acta Scientiarum - Agronomy 27 (2), 2005, p.287-292 (Journal


No evidence


Pear millet (Pennisetum glaucum) is high palatability by browsing and grazing animals. But purple majesty as deep purple leaves and stems and there is no evidence regarding its palatability in particular.


For P. glaucum - "Toxicity- none" [Don’t know - since purple majesty is deep purple in color and if this could affect toxicity].


"Common plant arthopods (insects/other)/other: Reported arthropod symptoms in literature: lesser cornstalk borer, European corn borer, corn earworm, fall armyworm and vegetable leafminer; other pests: sting nematode (Featured Creatures, U. of Florida an


Probably not - For P. glacum - "The plant is appetizer and tonic[240]. It is useful in the treatment of heart diseases. The fruits have been rubbed on open facial pimples in order to get rid of them." [No evidence that the ornamental purple majesty is ha


It thrives in high heat and unremitting sun, so grow it alongside the blazing driveway, in the foundation border, along the fence, or at the back of the patio near a warm wall. [Probably yes - adapted to high heat dry areas and is an annual growing over s


(1)Sun Exposure: Full Sun (2)"Purple Majesty’ can tolerate partial shade, but you will achieve the best color if planted in full sun". (3)Position - full sun" (4)"Sun exposure - full sun"

(1) (2) (3) (4)


(1)pH range 5.5 to 6.8 (2)The plant prefers light (sandy) and medium (loamy) soils, requires well-drained soil and can grow in nutritionally poor soil. The plant prefers acid, neutral and basic (alkaline) soils. (3)Soil Type : Normal Sandy Clay. So

(1) (2) (3)


No evidence


No evidence



An upright grass growing to a height of around 120 cm.




This ornamental hybrid was originally discovered in Nebraska - there is no evidence of reproductive failure in purple majesty.


(1)Propagated by seed. (2)Germination will usually take 3 to 10 days.

(1) (2)


(1)Purple majesty is or hybrid origin - but no evidence regarding the parental species. "Dr. Andrews and research manager John Rajewski selected the best parents from their crop of purple millet, hybridizing them to produce 'Purple Majesty', which they en

(1) (2)Genomic analysis in Pennisetum purpureum x P. glaucum hybrids . By: Techio, V. H.; Caryologia 58 (1), 2005, p.28-33 (Journal article)


"Self-pollination can occur when stigma emergence on later flowering tillers overlaps with the anthesis of earlier heads on the same plant. In random-mating situations (as in landrace cultivar populations or breeder created populations--synthetics or comp


"The flowers are hermaphrodite (have both male and female organs) and are pollinated by Wind." [This refers to P. glaucum, however no evidence to believe that the pollination mode is different for 'purple majesty']


(1)For Pennisetum glaucum - "Vegetative spread rate - none" [No evidence that purple majesty spreads by vegetative means].


(1)An annual species. (2)Annual growing to 0.5m. (3)"'Purple Majesty' is an annual in the garden. It grows quickly, requiring about 60 to 70 days from seed to flower."

(1) (2) (3)


(1)Plant Uses & Characteristics
Accent: Good Texture/Form
Cut Flower
Dried Flower
Drought Tolerant
Specimen (2)"Purple Majesty’ grows to 5 feet tall making it an excellent addition at the back of the borde

(1) (2)


(1)"Thanks to a serendipitous discovery in a University of Nebraska-Lincoln breeding program, a showy version of a plant normally used for forage or grain this year receives the 2003 All-America Selections Gold Medal Flower award. The Gold Medal award is

(1) (2) (3)


Probably yes - since it is a seed crop and could be a contaminant with cultivated pearl millet (P. glaucum).


The wild millet seed dispersal is by wind, however domestication has affected the seed dispersal of the cultivated millet. The non shedding seeds with reduced bracts and bristles of the cultivated millet are less likely to be dispersed long distance by w

(1) (2)Genetic control of domestication traits in pearl millet (Pennisetum glaucum L., Poaceae) . By: Poncet, V.; Theoretical and Applied Genetics 100 (1), 2000, p.147-159 (Journal arti


No evidence that purple majesty inhabits or is grown near water ways.


Probably not - birds eat the seeds (most granivorous birds crack the seeds - rendering then unviable after ingestion. (1)"Prominent seed heads are great food sources for birds, and are useful for dried flower arrangements." (2)Featue - bird lovers.

(1) (2)


Probably not - no evidence that the species has any means of attachment.


Probably not - birds eat the seeds but most granivorous birds crack the seeds - rendering then unviable after ingestion. (1)"Prominent seed heads are great food sources for birds, and are useful for dried flower arrangements." (2)Featue - bird lovers.

(1) (2)


Probably yes - "Fruit/seed abundance - Height." "Seeds per pound - 82320" -This reference pertains to Pennisetum glaucum in general but no evidence that the seed yield of purple majesty in low.


"Abstract: Storage conditions can affect seed viability. Seven pearl millet (Pennisetum glaucum (L.) R.Br.) cultivars were kept for six years under three storage conditions: ambient [, 20-90% relative humidity(RH)], short-term (



No evidence that purple majesty is being controlled for.


Probably not - does not tolerate regenerate, does not tolerate fire.


Don’t know.

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This page created 23 December 2006