Naples onion (Allium neapolitanum)

Present distribution

Scientific name:	Allium neapolitanum Cirillo
Common name(s):	Naples onion, white garlic

Map showing the present distribution of this weed.

Habitat:

Grows in grassy places, fields (Phillips, Rix 1989), open pastures (O’Donnell, Gibbons 2007) cultivated grounds, dry, open habitats (Carotenuto et al.
1997), among hard, Jurassic limestone rocks, subruderal habitats (Kollmann, Shmida 1977). Various types of soils, along the coastal plain and on
mountain slopes (Galil 1965), on any soil (Ogden 2007). Tolerant to waterlogging (Ogden 2007) and drought, intolerant to salinity (Fern 2000).

Potential distribution

Potential distribution produced from CLIMATE modelling refined by applying suitable landuse and vegetation type overlays with CMA boundaries

Map Overlays Used

Land Use:
Pasture dryland; pasture irrigated

Ecological Vegetation Divisions
Grassy/heathy dry forest; lowland forest; foothills forest; forby forest; high altitude shrubland/woodland; high altitude wetland; alpine treeless; granitic hillslopes; rocky outcrop shrubland; basalt grassland; alluvial plains grassland; semi-arid woodland; riverine woodland/forest

Colours indicate possibility of Allium neapolitanum infesting these areas.

In the non-coloured areas the plant is unlikely to establish as the climate, soil or landuse is not presently suitable.

Red= Very high	Orange = Medium
Yellow = High	Green = Likely

Impact

QUESTION	COMMENTS	RATING	CONFIDENCE
Social
1. Restrict human access?	Grows to 30 cm (Fragman-Sapir 2003) – minimal or negligible impact	l	m
2. Reduce tourism?	Grows to 30 cm (Fragman-Sapir 2003) – weeds not obvious to the average visitor	l	m
3. Injurious to people?	Causes skin irritation (Al-Qura’n 2005) – cause serious allergies to humans throughout the year.	h	h
4. Damage to cultural sites?	Bulbs shallow in soil (Galil 1965) and grows to 30 cm (Fragman-Sapir 2003) – little or negligible effect on aesthetics or structure of site	l	mh
Abiotic
5. Impact flow?	Terrestrial (Carotenuto et al. 1997) – little or negligible affect on water flow	l	h
6. Impact water quality?	Terrestrial (Carotenuto et al. 1997) – no noticeable effect on dissolved oxygen or light levels	l	h
7. Increase soil erosion?	Leaves “wither before flowering time” (Brickell 1996) and is then “dormant throughout the summer” (Mann 1960) – moderate probability of large scale soil movement	ml	m
8. Reduce biomass?	Grows to 30 cm (Fragman-Sapir 2003) in “grassy places and fields” (Phillips, Rix 1989) – direct displacement of biomass by invader	ml	mh
9. Change fire regime?	Grows to 30 cm (Fragman-Sapir 2003) in “grassy places and fields” (Phillips, Rix 1989) – small or negligible effect on fire risk	l	mh
Community Habitat
10. Impact on composition (a) high value EVC	EVC = Valley Grassy Forest (V); CMA = Corangamite; Bioregion = Central Victorian Uplands; VH CLIMATE potential. “extremely well suited to the climate of south-eastern Australia and increases rapidly by both seed and offsets, so much so that it can become something of an irritation” (Hitchmough 1989). “When well sited, plants can sometimes self-sow to the point of nuisance” (PFAF 2008). “Grows in pastures, cultivated grounds, and dry, open habitats of the Mediterranean region” (Carotenuto et al. 1997) Major displacement of some dominant spp. within a strata/layer	mh	h
(b) medium value EVC	EVC = Rocky Outcrop Shrubland (R); CMA = East Gippsland; Bioregion = East Gippsland Uplands; VH CLIMATE potential. “extremely well suited to the climate of south-eastern Australia and increases rapidly by both seed and offsets, so much so that it can become something of an irritation” (Hitchmough 1989). “When well sited, plants can sometimes self-sow to the point of nuisance” (PFAF 2008). “Grows in pastures, cultivated grounds, and dry, open habitats of the Mediterranean region” (Carotenuto et al. 1997) Major displacement of some dominant spp. within a strata/layer	mh	h
(c) low value EVC	EVC = Heathy Dry Forest (LC); CMA = North East; Bioregion = Northern Inland Slopes; VH CLIMATE potential. “extremely well suited to the climate of south-eastern Australia and increases rapidly by both seed and offsets, so much so that it can become something of an irritation” (Hitchmough 1989). “When well sited, plants can sometimes self-sow to the point of nuisance” (PFAF 2008). “Grows in pastures, cultivated grounds, and dry, open habitats of the Mediterranean region” (Carotenuto et al. 1997) Major displacement of some dominant spp. within a strata/layer	mh	h
11. Impact on structure?	“extremely well suited to the climate of south-eastern Australia and increases rapidly by both seed and offsets, so much so that it can become something of an irritation” (Hitchmough 1989). “When well sited, plants can sometimes self-sow to the point of nuisance” (PFAF 2008). “Grows in pastures, cultivated grounds, and dry, open habitats of the Mediterranean region” (Carotenuto et al. 1997) – major effect on <60% of the floral strata	mh	m
12. Effect on threatened flora?	Although “it can become something of an irritation” in south-eastern Australia (Hitchmough 1989) the effects on threatened flora are unknown	mh	l
Fauna
13. Effect on threatened fauna?	Although “it can become something of an irritation” in south-eastern Australia (Hitchmough 1989) the effects on threatened flora are unknown	mh	l
14. Effect on non-threatened fauna?	“extremely well suited to the climate of south-eastern Australia and increases rapidly by both seed and offsets, so much so that it can become something of an irritation” (Hitchmough 1989). “When well sited, plants can sometimes self-sow to the point of nuisance” (PFAF 2008). “Grows in pastures, cultivated grounds, and dry, open habitats of the Mediterranean region” (Carotenuto et al. 1997) – minor effects on fauna spp.; minor hazard or reduction in habitat/food/shelter	ml	m
15. Benefits fauna?	Listed as “rarely damaged” by deer (Jett 2006). “The juice of this plant is used as a moth repellent. The whole plant is said to repel insects and moles.” Grows to 30 cm (PFAF 2008) – provides very little support to desirable species	h	m
16. Injurious to fauna?	“Allium species seldom cause illness of animals in Britain, but eating any plant in this genus may result in a taint in both milk and meat” (Cooper, Johnson 1984) – mildly toxic, may cause fauna to loose condition	ml	m
Pest Animal
17. Food source to pests?	Said to deter rabbits and “the juice of this plant is used as a moth repellent. The whole plant is said to repel insects and moles” (PFAF 2008) – provides minimal food for pest animals	l	m
18. Provides harbour?	Grows to 30 cm (Fragman-Sapir 2003) – no harbour for pest spp.	l	m
Agriculture
19. Impact yield?	It is an agricultural weed in California (Calflora 2009) and is “also a potential seed contaminant” (USDA 2009). And “can overrun agricultural areas” (Fragman-Sapir 2003) – serious impacts on quantity	h	ml
20. Impact quality?	“Allium species seldom cause illness of animals in Britain, but eating any plant in this genus may result in a taint in both milk and meat” (Cooper, Johnson 1984). “These species [incl. syn. Nothoscordum inodorum] generally impart an undesirable garlic or onion type flavour to contaminated food product including cereal grains, milk, meat, eggs, and poultry” (CDFA 2009) – serious impacts on quality – produce rejected for sale or export	h	m
21. Affect land value?	“These species [incl. syn. Nothoscordum inodorum] generally impart an undesirable garlic or onion type flavour to contaminated food product including cereal grains, milk, meat, eggs, and poultry” also difficult to control as “underground bulblets easily dislodge from the parent bulb when plants are manually removed” (CDFA 2009) – decrease land value < 10%	m	m
22. Change land use?	“These species [incl. syn. Nothoscordum inodorum] generally impart an undesirable garlic or onion type flavour to contaminated food product including cereal grains, milk, meat, eggs, and poultry” also difficult to control as “underground bulblets easily dislodge from the parent bulb when plants are manually removed” (CDFA 2009) – downgrading of the priority of land use, to one with either less agricultural return	mh	m
23. Increase harvest costs?	“Potential seed contaminant” (USDA 2009) – major increase in time or labour, or machinery in harvesting	h	m
24. Disease host/vector?	“Both edible and ornamental species [of Allium] have the same pest and disease enemies such as onion fly, stem eelworm, rust and onion white rot” (Page, Olds 1998) – host to major and severe disease or pest of important agricultural produce	h	m

Invasive

QUESTION	COMMENTS	RATING	CONFIDENCE
Establishment
1. Germination requirements?	“In November, after the first rains, all bulblets formed in the previous year begin to sprout” (Galil 1965) and “bulbs, stored at 4˚C for 8 weeks, produced flower stalks 35 days earlier than did those bulbs which were not exposed to winter storage” (Maeda et al. 1994) – requires natural seasonal disturbances such as seasonal rainfall, spring/summer temperatures for germination.	mh	h
2. Establishment requirements?	Occurs in the shade of trees (Kollmann, Shmida 1977) and is “easily grown in sunny places” (Phillips, Rix 1989) – can establish without additional factors.	h	h
3. How much disturbance is required?	“Grows in pastures, cultivated grounds, and dry, open habitats” (Carotenuto et al. 1997). Occurs in disturbed habitat in California (Calflora 2009). “Increases rapidly on any soil” (Ogden 2007) – establishes in relatively intact OR only minor disturbed natural ecosystems	mh	m
Growth/Competitive
4. Life form?	Bulbous perennial (Brickell 1996) – geophyte	mh	m
5. Allelopathic properties?	“Inhibits the growth of legumes” (PFAF 2008) – allelopathic properties seriously affecting SOME plants	mh	ml
6. Tolerates herb pressure?	Listed as “rarely damaged” by deer (Jett 2006). “The juice of this plant is used as a moth repellent. The whole plant is said to repel insects and moles.” (PFAF 2008) – favoured by heavy grazing pressure as not eaten by animals/insects and not under a biological control program in Australia/New Zealand	h	m
7. Normal growth rate?	“increases rapidly on any soil” (Ogden 2007) – rapid growth rate that will exceed most other species of the same life form	h	ml
8. Stress tolerance to frost, drought, w/logg, sal. etc?	“said to be rather frost tender” (Phillips, Rix 1989). However “the dormant bulbs are fairly hardy and will withstand soil temperatures down to at least -5°C” (PFAF 2008). Listed under “Plants for dry soil” and not listed under “Plants for saline soils” (Fern 2000). “This plant is not hardy enough to overcome frost periods and is adapted to dry warm summer conditions... The higher the night temperature, the higher was the total yield of bulbs” (Zimmer, Weckeck 1989). Drought tolerant (Dave’s Garden 2009). Has the “capacity to grow in waterlogged soils during the cool spring months” and “will bloom happily even in standing water” (Ogden 2007). Highly resistant to drought, waterlogging; tolerant to frost; intolerant to salinity.	h	m
Reproduction
9. Reproductive system	“Increases rapidly by both seed and offsets” (Hitchmough 1989) – Both vegetative and sexual reproduction.	h	m
10. Number of propagules produced?	“Under favourable conditions, up to 15 spherical bulblets are produced annually in the axils of the foliage leaves of a mature plant. After the disintegration of the subtending leaves, these bulblets are freed from the mother plant... These rapidly increase in size from year to year through the migration of the bulblets in the soil” (Galil 1965). Seeds numerous [as syn. Nothoscordum inodorum] (CDFA 2009)	h	m
11. Propagule longevity?	Unknown	m	l
12. Reproductive period?	Perennial (CDFA 2009) – mature plant produces viable propagules for 3-10 years	mh	m
13. Time to reproductive maturity?	“Plants of A. neapolitanum usually reach maturity in early of mid-April, after which time the leaves, roots and stems of the current season die, leaving only the main and increase bulbs to perpetuate the plants. The protective leaves of these bulbs also die and, as the leaf bases and exterior tissues decay, a cluster of spherical bulbs is set free” (Mann 1960). “The bulblets of A. neapolitanum... become detached from the mother bulb during the year in which they are formed” (Galil 1965) – reaches maturity and produces viable propagules, or vegetative propagules become separate individuals in under a year.	h	h
Dispersal
14. Number of mechanisms?	It is commercially available in Victoria (Randall 2004), therefore is deliberately dispersed by humans. It is also a prolific self-seeder with small seeds, it is likely that it is wind dispersed also, however this is unknown	m	l
15. How far do they disperse?	Unknown	m	l

References

Al-Qura’n S (2005) Ethnobotanical survey of folk toxic plants in southern part of Jordan. Toxicon 46, 119-129.

Brickell C edt. (1996) The royal horticultural society, A-Z encyclopedia of garden plants. Dorling Kindersley, London.

Calflora (2009) Taxon report 214 Allium neapolitanum. Calflora: Information on California plants for education, research and conservation. Available at http://www.calflora.org/cgibin/species_query.cgi?where-calrecnum=214 (verified 25 February 2009).

Carotenuto A, Fattorusso E, Lanzotti V, Magno S, De Feo V, Cicala C (1997) The flavanoids of Allium neapolitanum. Phytochemistry 44(5), 949-957.

CDFA (2009) i. Californian Department of Food and Agriculture. Available at http://www.cdfa.ca.gov/phpps/IPC/weedinfo/nothoscordum.htm (verified 17 April 2009).

Conor HE (1977) The poisonous plant in New Zealand. E.C. Keating. Government Printer, Wellington.

Cooper MR, Johnson AW (1984) Poisonous plant in Britain and their effects on animals and man. Her Majesty’s Stationary Office, London.

Dave’s Garden (2009) Plant Files: Naples onion, white garlic. Available at http://davesgarden.com/guides/pf/go/2771/ (verified 25 February 2009).

Fern K (2000) Plants for a future: edible & useful plants for a healthier world. Permanent Publications.

Fragman-Sapir O (2003) Wild Allium species in Israel – Potential cut flowers and garden plants. Jerusalem University Botanic Gardens. Available at http://www.botanic.co.il/english/research/Allium.htm (verified 17 April 2009).

Galil J (1965) Vegetative dispersal of Allium neapolitanum. American Journal of Botany 52(3), 282-286.

Hitchmough J (1989) Garden bulbs; a seasonal planting and flowering guide for all Australian regions. Viking O’Neil, Melbourne.

Israel Plant Gene Bank (IGB) (2009) Taxonomy results – Allium neapolitanum. Available at http://igb.agri.gov.il/main/resultat11.pl?GENUS=Allium&SPAUTHOR=Cirillo&SPECIES=neapolitanum (verified 1 April 2009).

Jett JW (2006) Resistance of ornamentals to deer damage. University of Maryland. Available at http://twraregion4.org/TWRAHunting/files/DeerPublicationOrnamentalsResistance.pdf (verified 25 February 2009)

Kollmann F, Shmida A (1977) Allium species of Mt. Hermon. I. Taxonomy. Israel Journal of Botany 26, 128-148.

Mann LK (1960) Bulb organization in Allium: some species of the section Molim. American Journal of Botany 47, 765-771.

Meada M, Dubouzet JG, Arisumi, K, Etoh T, Sakata Y (1994) Effects of cold storage and staggered planting in forcing culture of spring-flowering Allium species. Journal of the Japanese Society for Horticultural Science 63(3), 629-638.

Ogden S (2007) Garden bulbs for the south. 2nd Edition. Timber Press.

Page S, Olds M (Managing Editors) (1998) Botanica; the illustrated A-Z of over 10,000 garden plants and how to cultivate them. Random House Australia, Sydney.

Plants for a Future Database (PFAF) (2008) Allium neapolitanum. Available at http://www.pfaf.org/database/plants.php?Allium+neapolitanum (verified 25 February 2009).

Phillips R, Rix M (1989) The pan garden plants series: Bulbs. Pan Books, Essex.

USDA (2009) GRIN taxonomy for plants. United States Department of Agriculture. Agricultural Research Service, Beltsville Area. Available at http://www.ars-grin.gov/cgibin/npgs/html/taxon.pl?2324 (verified 25 February 2009).

Randall R (2004) Rod Randall’s Big Weed List. The Nature Conservancy. Available at http://www.invasive.org/gist/global/australia/aca.html (verified 22 April 2009).

Rice EL (1984) Allelopathy, 2nd Edition. Academic Press, Orlando, Florida.

Zimmer K, Walingen M, Renken M (1985) Investigation on the periodical development of Allium aflatunense. Deutscher Gartenbau 39(12), 594-596.

Zimmer K, Weckeck K (1989) Effect on temperature on some ornamental Alliums. Acta Horticulturae 246, 131-134.

Global present distribution data references

Australian National Herbarium (ANH) (2009) Australia’s Virtual Herbarium, Australian National Herbarium, Centre for Plant Diversity and Research, Available at http://www.anbg.gov.au/avh/ (verified 17 April 2009).

Global Biodiversity Information Facility (GBIF) (2009) Global biodiversity information facility, Available at http://www.gbif.org/ (verified 17 April 2009).

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