Research directed by C. Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service

Information on Risk Assessments
Original risk assessment

Nerium oleander (Oleander, Oliwa)

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

n

1.02

Has the species become naturalized where grown?

y=-1, n=-1

y

1.03

Does the species have weedy races?

y=-1, n=-1

n

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”

See Append 2

1

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

n

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

n

2.05

Does the species have a history of repeated introductions outside its natural range? y=-2

?=-1, n=0

y

3.01

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

y

3.02

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

n=0

n

3.03

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

n=0

n

3.04

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

n=0

y

3.05

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

n=0

n

4.01

Produces spines, thorns or burrs

y=1, n=0

n

4.02

Allelopathic

y=1, n=0

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

y

4.05

Toxic to animals

y=1, n=0

y

4.06

Host for recognized pests and pathogens

y=1, n=0

n

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

y

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

n

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

y

4.11

Climbing or smothering growth habit

y=1, n=0

n

4.12

Forms dense thickets

y=1, n=0

n

5.01

Aquatic

y=5, n=0

n

5.02

Grass

y=1, n=0

n

5.03

Nitrogen fixing woody plant

y=1, n=0

n

5.04

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

y=1, n=0

n

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

6.02

Produces viable seed.

y=1, n=-1

y

6.03

Hybridizes naturally

y=1, n=-1

n

6.04

Self-compatible or apomictic

y=1, n=-1

y

6.05

Requires specialist pollinators

y=-1, n=0

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

n

6.07

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

See left

7.01

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

y=1, n=-1

n

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

n

7.04

Propagules adapted to wind dispersal

y=1, n=-1

y

7.05

Propagules water dispersed

y=1, n=-1

y

7.06

Propagules bird dispersed

y=1, n=-1

n

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

n

7.08

Propagules survive passage through the gut

y=1, n=-1

n

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

y

8.02

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

y=1, n=-1

n

8.03

Well controlled by herbicides

y=-1, n=1

8.04

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

y=1, n=-1

y

8.05

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

y=-1, n=1

Total score:

6

Notes

Source

1.01

The plant produces terminal flower heads, usually pink or white, however, 400 cultivars have been bred and these display a wide variety of different flower colour: deep to pale pink, lilac, carmine, purple, salmon, apricot, copper, orange and white

http://www.intox.org/pagesource/intox%20area/pims/pim366.htm

1.02

(1)Naturalized in California. (2)CA:Horticultural; not invasive, although reported from riparian areas in Central Valley, San Bernardino Mtns.

(1)http://waynesword.palomar.edu/jackpond.htm (2)http://www.caleppc.org/Pest_Plant_List/Considered_But_Not_Listed.htm

1.03

No evidence

2.01

(1)Where the species grows in the wild (i.e. in the Mediterranean), it occurs along watercourses, gravely places and damp ravines. (2)it is native only in the Mediterranean region (3)Native to northern Africa, the eastern Mediterranean basin and southeast Asia.

(1) and (2)http://www.intox.org/pagesource/intox%20area/pims/pim366.htm (3)http://www.floridata.com/ref/n/nerium.cfm

2.02

(1)Oleander prefers dry, warm climates and may naturalize in such areas. (2) It is widely cultivated particularly in warm temperate and subtropical regions where it grows outdoors in parks, gardens and along road sides. Elsewhere, where the plant is not frost-tolerant (e.g. in central and western Europe), it may be grown as a conservatory or patio plant.

(1) http://www.floridata.com/ref/n/nerium.cfm (2)http://www.intox.org/pagesource/intox%20area/pims/pim366.htm

2.03

(1) Hardiness: USDA Zones 8-10. (2)River banks and river-gravels. Distribution: Mediterranaen region, S.Portugal; Jugoslovia, Adritic coast

(1)http://www.floridata.com/ref/n/nerium.cfm (2)http://utopia.ision.nl/users/aart/flora/Apocynaceae/Nerium/N.oleander.html

2.04

(1)Where the species grows in the wild (i.e. in the Mediterranean), it occurs along watercourses, gravely places and damp ravines. (2)it is native only in the Mediterranean region (3)Native to northern Africa, the eastern Mediterranean basin and southeast Asia.

(1) and (2)http://www.intox.org/pagesource/intox%20area/pims/pim366.htm (3)http://www.floridata.com/ref/n/nerium.cfm

2.05

It is widely cultivated particularly in warm temperate and subtropical regions where it grows outdoors in parks, gardens and along road sides. Elsewhere, where the plant is not frost-tolerant (e.g. in central and western Europe), it may be grown as a conservatory or patio plant. Although the plant is native to the Mediterranean basin, it has been introduced as an ornamental shrub in many tropical and subtropical countries (Mahin et al., 1984). The plant is common in Australia and southern Africa and ingestion of plant parts is one of the major causes of childhood admission to hospital.

http://www.intox.org/pagesource/intox%20area/pims/pim366.htm

3.01

(1)Naturalized in California. (2)CA:Horticultural; not invasive, although reported from riparian areas in Central Valley, San Bernardino Mtns.

(1)http://waynesword.palomar.edu/jackpond.htm (2)http://www.caleppc.org/Pest_Plant_List/Considered_But_Not_Listed.htm

3.02

No evidence

3.03

No evidence

3.04

(1)Environmental weed of unknown importance in Queensland and Western Australia (2)Mitcham Council (Australia) list of invasive plants, severity rating 3 (out of 5). (3)Weed invading bush (South Australia) (4)Localized environmental weed in KwaZulu-Natal South Africa

(1)Randall, R. 2001. Garden thugs, a national list of invasive and potentially invasive garden plants. Plant Protection Quarterly 16:138-171. (2)http://www.mitchamcouncil.sa.gov.au/content/heritage/weeds/weeds.htm (3)http://www.urbanforest.on.net/backyard-q07.htm (4)http://www.kznwildlife.com/mngt_alienp.htm

3.05

No evidence

4.01

No evidence

http://www.floridata.com/ref/n/nerium.cfm

4.02

(2) AB: Diluted extracts obtained from Eucalyptus camaldulensis (red river gum), Juglans regia (walnut tree), Melia azedarach (china berry tree), Nerium oleander (common oleander) and Raphanus sativus (garden radish) were applied to the seeds of winter weeds such as Alopecurus myosuroides (blackgrass), Lactuca sativa (lettuces), Lolium multiflorum (Italian rye-grass) and Raphanus raphanistrum (wild radish) and summer Amaranthus retroflexus (red root), Digitaria sanguinalis (crab-grass), Portulaca oleracea (common purslane), Prosopis stephaniana (mesquite) and Xanthium strumarium (cocklebur). Percentage germination was evaluated on the 3rd, 5th, 7th, 14th, 21st and 28th days of the experiment. Diluted extracts of N. oleander and M. azedarach resulted in the greatest inhibition of germination.
(3) AB: The allelopathic effects of 2.5-5.0 kg/ha fresh wt. leaf residues of Nerium oleander, Schanginia [Suaeda ] aegyptiaca, Tamarex articulata [Tamarix aphylla ], lucerne, liquorice, sunflower

(3) Al-Juboory, B. A.; Ahmad, M. M. (1994) The allelopathic effects of plant residues on some weed plants. Arab Journal of Plant Protection, 1994, Vol.12, No.1, pp.3-10

4.03

No evidence

4.04

unpalatable

http://plants.usda.gov/

4.05

(1) 'One leaf of N. oleander may be sufficient to kill a sheep (Shaw & Pearn, 1979). The lethal dose of N. oleander leaves reported for several animal species is about 0.5 mg/kg. Animals poisoned by eating the plant often develop bloody diarrhea, due to a direct effect on the gastrointestinal tract. The bitter and astringent taste of the plant's leaves means that all but starving creatures are likely to be exposed.' (2)AB: The oleander poisoning was observed in four cattle of a small herd which resulted in death of three animals, two pregnant heifers and a young bull, within 24 h. The clinical signs were inappetance, diarrhea, depression and cardiac arrhythmias. The diagnosis was done according to the clinical and electrocardiographic findings, and the presence of fresh Nerium oleander leaves in the fodders of the pen was noticed.

AU: Aslani-M-R {a}; Rezakhani-A SO: International-Journal-of-Tropical-Agriculture. [print] June, 2000; 18 (2): 185-187..

4.06

(1) Diseases: Oleander (bacterial) leaf scorch is a serious disease in California caused by the bacterium Xylella fastidiosa. The disease is spread by a leafhopper. Infected plants take about 2 years to die. It is likely to spread to other southern states. Sphaeropsis gall infects plants in the east causing a witches broom. It is a huge problem in some parts of the plants' range including Florida. Fungus spreads in wet weather during active growth. Branches die back. There is little to do about this other than prune out the infected portion of the plant. Perform this in dry weather so you do not spread the fungus to other oleander plants. (2) This site liste 115 fungi species to be associated with N. oleander. (3) Corss ref (1) - ''Xylella fastidiosa (Xf) causes such diseases as Pierce's disease of grapes, citrus variegated chlorosis, and phony peach disease. The bacterium, found in xylem tissue, has a large host range, including at least 28 families of both monocotyleyledonous and dicotyledonous

(1)Horticopia A to Z. CD-ROM database. (2)http://nt.ars-grin.gov/fungaldatabases/all/FindRecOneFungusFrame.cfm (3)http://www.agdia.com/cgi_bin/catalog.cgi/34501 (4)http://mrec.ifas.ufl.edu/jos/Sphaeropsis.htm

4.07

All parts are very poisonous if eaten. Poisonous Plant Parts - Not for Human Consumption All parts of this plant, including the sap, either fresh, dried or boiled, are toxic.... A single leaf intensively chewed has been reported to be lethal. ... The plant is common in Australia and southern Africa and ingestion of plant parts is one of the major causes of childhood admission to hospital (Shaw & Pearn, 1979). ... A single leaf may be lethal to a child (Shaw & Pearn, 1979). ... Sap contains an unidentified irritant of the mucous membranes of the mouth and intestine (NCPCC, 1979).

http://www.intox.org/pagesource/intox%20area/pims/pim366.htm

4.08

High fire tolerance [evergreen]

http://plants.usda.gov/

4.09

(1) Sun Exposure: Prefers full sun, will take light shade. Tolerates reflective heat. (2) Shade intolerant (3)Light requirement: full sun, partial sun or partial shade

(1)http://www.desert-tropicals.com/Plants/Apocynaceae/Nerium_oleander.html (2)http://plants.usda.gov/ (3)http://edis.ifas.ufl.edu/ST416

4.1

(1)The plant prefers medium (loamy) and heavy (clay) soils, requires well-drained soil and can grow in heavy clay soil. The plant prefers acid, neutral and basic (alkaline) soils. (2)pH range 5.5 7.8 (3)Soil Condition Loamy, sandy, clay, acidic, neutral, slightly alkaline, tolerates salt, drought tolerant

(1)http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Nerium+oleander (2)http://plants.usda.gov/ (3)Horticopia A to Z. CD-ROM database.

4.11

Not a climber - a shrub.

http://www.intox.org/pagesource/intox%20area/pims/pim366.htm

4.12

No evidence

5.01

N. oleander is an evergreen shrub reaching four metres in height.

http://www.intox.org/pagesource/intox%20area/pims/pim366.htm

5.02

5.03

No nitrogen fixed.

http://plants.usda.gov/

5.04

6.01

'AB: This study presents data on the reproductive characteristics of Nerium oleander, an evergreen, sclerophyllous shrub inhabiting the banks of temporary streams in all countries around the Mediterranean seabord. Two southern Spanish populations (El Garrobo and Grazalema) were selected to investigate flowering, dispersal and seed germination phenologies, together with morphological and functional traits of flowers, fruits and seeds. Observations on pollinating visitation, fruit set, and seedling survival were carried out. Plants produce massive flower display of showy, tubular flowers void of nectar that rely on insect cheating for pollination. ... '

PY: 1991

6.02

'... The hairy, water-dispersed seeds are released during the rainiest season in the year, and germination follows rapidly. All seedlings tracked died before completing 1 year of life, mostly because of desiccation during the first summer drought.. …'

TI: THE REPRODUCTIVE BIOLOGY OF A RIPARIAN MEDITERRANEAN SHRUB NERIUM-OLEANDER L. APOCYNACEAE.
AU: HERRERA-J {a}
SO: Botanical-Journal-of-the-Linnean-Society. 1991; 106 (2): 147-172..
PY: 1991

6.03

monospecific genus

6.04

'… Hand-pollinations and seed germination tests demonstrated full self-compatibility. '

TI: THE REPRODUCTIVE BIOLOGY OF A RIPARIAN MEDITERRANEAN SHRUB NERIUM-OLEANDER L. APOCYNACEAE.
AU: HERRERA-J {a}
SO: Botanical-Journal-of-the-Linnean-Society. 1991; 106 (2): 147-172..
PY: 1991

6.05

(1)and (2)Pollinators/visitors: Xylocopa violacea (Hymenoptera: Apidae) and Diptera: Calliphoridae sp., Xylocopa violacea (Hymenoptera: Apidae), Hymenoptera: Halictidae sp. - In al the above cases 'Identity of the pollinator inferred; insects observed with pollen attached, under natural conditions.' in Europe. (3)Hawkmoth pollinted
(4) AB: '"Plants produce massive flower display of showy, tubular flowers void of nectar that rely on insect cheating for pollination." ; "Low pollinator visitation rates are the rule, as indicated by the fact that observations spread over 2 years yielded only eight insect records." ; " The pollen is aggregated into a sticky substance, which allows the fertilization of many ovules after a single, probably rare, pollination event" [few pollinator visits, nectarless flower, rare pollination event]

(1) http://www.uni-bayreuth.de/departments/planta2/research_wgl/pollina/APO_POL_t.html (2)http://www.uni-bayreuth.de/departments/planta2/research_wgl/pollina/APO_POL_d.html (3)http://www.botgard.ucla.edu/html/MEMBGNewsletter/Volume4number2/Theplantsthatlovehawkmoths.html
(4) Herrera, J. (1991) The reproductive biology of a riparian Mediterranean shrub, Nerium oleander L. (Apocynaceae). Botanical Journal of the Linnean Society, 1991, Vol.106, No.2, pp.147-172, 55 ref.

6.06

(1)Propagation: Semiripe cuttings are best rooted in summer. Also by seed, …. By removing suckers, and leaving just a few stems, oleander can be formed into very attractive small trees. (2)No vegetative spread.
(3)"suckers produced at the base of the plant" [basal suckers only, not a means of spread or natural fragmentation]

(1)http://www.floridata.com/ref/n/nerium.cfm (2)http://plants.usda.gov/ (3) Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7.

6.07

Don’t know

7.01

No evidence that the seeds have any means of attachment.

7.02

N. oleander is cultivated worldwide as an ornamental plant

http://www.intox.org/pagesource/intox%20area/pims/pim366.htm

7.03

probably not - seeds with crown of silky hair.

http://waynesword.palomar.edu/plfeb99.htm

7.04

(1) Parachute seeds escaping from the follicle of Nerium oleander. The crown of silky hairs arises directly from the top of the seed (2)Fruit: 3-5in long pods, green ripening to brown, splits to release airborne seed
(3) The fruit consists of a long narrow capsule 10 to 12 cm long and 6 to 8 mm in diameter; they open to disperse fluffy seeds.

(1) http://waynesword.palomar.edu/plfeb99.htm (2)http://ag.arizona.edu/pima/gardening/aridplants/Nerium_oleander.html (3)http://www.intox.org/pagesource/intox%20area/pims/pim366.htm

7.05

'... The hairy, water-dispersed seeds are released during the rainiest season in the year, and germination follows rapidly. …'

TI: THE REPRODUCTIVE BIOLOGY OF A RIPARIAN MEDITERRANEAN SHRUB NERIUM-OLEANDER L. APOCYNACEAE.
AU: HERRERA-J {a}
SO: Botanical-Journal-of-the-Linnean-Society. 1991; 106 (2): 147-172..
PY: 1991

7.06

No evidence

7.07

No evidence that the seeds have any means of attachment.

7.08

No evidence of ingestion

8.01

' ...Fruits are many seeded follicles (181 seeds per fruit on average) , so that individual plants often liberate thousands of seeds in spite of the low percent fruit set. ...'

Herrera, J. (1991) The reproductive biology of a riparian Mediterranean shrub, Nerium oleander L. (Apocynaceae). Botanical Journal of the Linnean Society, 1991, Vol.106, No.2, pp.147-172, 55 ref.

8.02

'... The hairy, water-dispersed seeds are released during the rainiest season in the year, and germination follows rapidly….' [probably not - no dormancy -germinate rapidly after seed set.'

8.03

Tolerant of pre and post emergence herbicides.

http://edis.ifas.ufl.edu/BODY_WG062

8.04

(1)Trim the tips of the stems after the flowers have dropped. Don't hesitate to cut back severely (to the ground if necessary). … Removing the shoots at the base of the flower clusters promotes blooming. (2)Coppice potential- yes. Resprout ability - yes.

(1)http://www.desert-tropicals.com/Plants/Apocynaceae/Nerium_oleander.html (2)http://plants.usda.gov/

8.05

Don’t know