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

Adenium obesum (Forssk.) Roem. & Schult.; desert rose

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

n

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

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

n

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

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

n

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

n

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

n

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

n

4.1

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

y=1, n=0

n

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

y

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

n

6.05

Requires specialist pollinators

y=-1, n=0

y

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

2

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

n

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

n

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

y

8.04

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

y=1, n=-1

n

8.05

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

y=-1, n=1

Total score:

-8

Notes

Source

1.01

"Up until recently, relative few horticulturists were selecting improved cultivars or doing hybridizing. Several nice named cultivars are currently in the trade (see photos). In recent times, many nurseries in Asia, especially Taiwan and Thailand, have been producing dozens (maybe hundreds) of named cultivars."

http://www.hort.wisc.edu/mastergardener/Features/flowers/desert%20rose/adenium.htm

1.02

no evidence

1.03

no evidence

2.01

Native distributional range:
AFRICA
Northern Africa: Egypt
Northeast Tropical Africa: Ethiopia; Sudan
East Tropical Africa: Tanzania
West Tropical Africa: Guinea; Mali; Nigeria; Senegal

URL: http://www.ars-grin.gov/var/apache/cgi-bin/npgs/html/tax_search.pl?desert-rose (21 May 2004)

2.02

2.03

(1) USDA: 11-12. Frost Tolerance: Hardy to 34°F (1°C). Extended periods below 40°F (4°C) will kill some of the branch tips.
(2) Hardiness Range 9A to 11 (3)dry climates in sub-Saharan Africa and the very southern part of the Arabian Peninsula

(1) http://www.desert-tropicals.com/Plants/Apocynaceae/Adenium_obesum.html
(2) Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7. (3)http://www.hort.wisc.edu/mastergardener/Features/flowers/desert%20rose/adenium.htm

2.04

Native distributional range:
AFRICA
Northern Africa: Egypt
Northeast Tropical Africa: Ethiopia; Sudan
East Tropical Africa: Tanzania
West Tropical Africa: Guinea; Mali; Nigeria; Senegal

URL: http://www.ars-grin.gov/var/apache/cgi-bin/npgs/html/tax_search.pl?desert-rose (21 May 2004)

2.05

"Perhaps the principal misconception about desert rose concerns the perceived difficulties associated with growing the plant in a wet and warm climate such as that found in South Florida. Desert rose is, however, quite commonly cultivated in humid tropical areas such as Thailand, India and The Philippines."

http://miami-dade.ifas.ufl.edu/programs/commorn/publications/desert-rose.PDF

3.01

no evidence

3.02

no evidence

3.03

no evidence

3.04

no evidence

3.05

no evidence

4.01

no description of these traits

Whistler, A.W. (2000) Tropical Oramentals: a Guide. Timber Press, Inc., Portland, Oregon. 542pp. p.34

4.02

no evidence

4.03

no evidence

4.04

On the island of Socotra where introduced goats have decimated much of the native vegetation, the adeniums are left totally untouched

http://www.hort.wisc.edu/mastergardener/Features/flowers/desert%20rose/adenium.htm

4.05

Crude solvent extracts of roots and stem bark of Adenium obesum, known in Sudan as Megadery or Shagaret Elsim, were tested against mice (Mus musculus). Plant parts were chopped and milled to a fine powder and then extracted using dichloromethane (DCM), methanol (MeOH) or water. The 24 h LD50s were 9.69 and 22.10 g plant kg-1 body weight for DCM and water extracts of roots, respectively. The symptoms of toxicity were hyperthermia, hyperventilation, collapse and atony leading to death. No acute mortality was recorded for any MeOH extract of roots, nor any bark extracts.

Bala, A. E. A. Delorme, R. Grolleau, G. Bashir, N. H. H. (1998) Preliminary investigations on the acute toxicity of root and bark extracts of Adenium obesum (Forsk.), Apocynaceae to the white mice Mus musculus. Sudan Journal of Agricultural Research, 1998, Vol. 1, No. 1, pp. 65-67, 10 ref.

4.06

no evidence

4.07

"can cause skin irritation or more severe internal poisoning." (2)Poisonous Plant Parts - Not for Human Consumption

http://miami-dade.ifas.ufl.edu/programs/commorn/publications/desert-rose.PDF (2)http://florawww.eeb.uconn.edu/acc_num/199800179.html

4.08

succulent

Whistler, A.W. (2000) Tropical Oramentals: a Guide. Timber Press, Inc., Portland, Oregon. 542pp. p.34

4.09

Exposure: Full sun

Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7.

4.1

(1)Soil Condition Loamy, sandy, acidic, neutral, slightly alkaline, (2)Well drained soil, slightly alkaline, humus-rich.

(1)Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7. (2)http://www.floridagardener.com/pom/adenium.htm

4.11

Growth Habits: Shrub to 5 feet tall

http://www.desert-tropicals.com/Plants/Apocynaceae/Adenium_obesum.html

4.12

no evidence

5.01

terrestrial

5.02

shrub, Apocynaceae

5.03

shrub, Apocynaceae

5.04

they store water in their soft, swollen roots and stems

http://www.hort.wisc.edu/mastergardener/Features/flowers/desert%20rose/adenium.htm

6.01

no evidence

6.02

Propagation: Cuttings, seeds

http://www.desert-tropicals.com/Plants/Apocynaceae/Adenium_obesum.html

6.03

Adenium somalense crispum X Adenium obesum 'Grumbley White [no evidence of natural hybrids]

(1)http://www.cactus-mall.com/andre/hybrids.html (2)http://www.cactus-mall.com/andre/part6.html

6.04

(1) Seed production is not reliable, since pollination is often not successful, due to plants in cultivation being male or female sterile.
(2) Adeniums are generally not self-fertile; it usually requires two separate clones to produce viable seed.

(2) http://www.hort.wisc.edu/mastergardener/Features/flowers/desert%20rose/adenium.htm

6.05

(1) "Pollination mechanism conspicuously specialized (usually with a highly modified stylar head and specialised anthers). " [character of the family]
(2) The 1 1/2-2" diameter flowers are easily hand pollinated using the typical moth mimicking technique, but are often pollinated by our resident hawk or sphinx months. [description of a closely related taxa Pachypodium saundersii]
(3) flowers are salverform (tubular with flared lips), and range in color from deep purplish red, through pink to white. The many cultivars have flowers of various color blends, shapes and sizes (up to 3 inches). A few have the added bonus of an attractive fragrance. (4)propagation from seed is not reliable because of pollination problems.

(1) http://biodiversity.uno.edu/delta/angio/www/apocynac.htm
(2) http://www.lithops.net/pachypodium_saundersii_detail.htm
(3) http://miami-dade.ifas.ufl.edu/programs/commorn/publications/desert-rose.PDF (4)http://miami-dade.ifas.ufl.edu/programs/commorn/publications/desert-rose-production.PDF
(5) Rowley, G. D. (1980) The pollination mechanism of Adenium (Apocynaceae) [A. obesum]. National Cactus and Succulent Journal, 1980, Vol. 35, No. 1, pp. 2-5, 8 ref. [not available]

6.06

no evidence

6.07

(1)"Seed grown plants will often flower the same year" (2)Even young plants 2-3 years old and 6-8 inches tall can put on a beautiful floral display [the first reference seems less likely given succulent growth]

(1)http://miami-dade.ifas.ufl.edu/programs/commorn/publications/desert-rose.PDF (2)http://www.hort.wisc.edu/mastergardener/Features/flowers/desert%20rose/adenium.htm

7.01

no evidence

7.02

"widely cultivated for its succulent habit and prominent flowers"

Whistler, A.W. (2000) Tropical Oramentals: a Guide. Timber Press, Inc., Portland, Oregon. 542pp. p.34

7.03

no evidence

7.04

"The fruit, which is classified as a follicle, splits along one side to release seeds bearing a pappus (tuft of hairs which aids in dispersal)) at each end."

http://miami-dade.ifas.ufl.edu/programs/commorn/publications/desert-rose.PDF

7.05

no evidence

7.06

"The fruit, which is classified as a follicle, splits along one side to release seeds bearing a pappus (tuft of hairs which aids in dispersal) at each end."

http://miami-dade.ifas.ufl.edu/programs/commorn/publications/desert-rose.PDF

7.07

no evidence

7.08

no evidence of ingestion

8.01

(1) The seeds in the pods are 4 - 5 mm longbrown sticks with hairy ends
(2) 40,000 seeds per KG [seed medium in size]

(1) http://www.seedcoseeds.com/seedtalk2/_seedtalk/000009d1.htm
(2) http://www.sevenluck.com/seed.htm

8.02

(1) "If fresh viable seed is available, germination rates are high if it is used promptly. Germination occurs within a week at 85 degree F." (2) "fresh seeds germinate rapidly, usually in 3-7 days, and seedlings tend to be vigorous" (3)Adenium seeds are perishable. For best result, sow it within 20 days from the date of plucking. Germination period starts after 3 days of sowing.

(1) http://miami-dade.ifas.ufl.edu/programs/commorn/publications/desert-rose.PDF (2) http://www.hort.wisc.edu/mastergardener/Features/flowers/desert%20rose/adenium.htm (3)http://www.goldenfloriculture.com/adenium_obesum.htm

8.03

(1)Warning; do not use any pre-emergent herbicide with the active ingredient oryzalin (e.g., Surflan) on adeniums… A single application permanently arrests root growth and the plants slowly die. (2)t got a whiff of Command herbicide and did not recover

(1)http://www.cactus-mall.com/andre/large.html (2)http://plantsdatabase.com/go/527

8.04

"Inspect plants after any cold weather for damage to branches, since this renders them more prone to subsequent rot that can then spread to healthy parts of the plant. Any cold damaged branches (look for burnt leaves and a loss of turgor) should be removed." [probably not. damadged plants are prone to rot] (2)Do heavy pruning after the plant's rest period. However, it bleeds profusely, so heavy pruning should be kept to a minimum.

(1)http://miami-dade.ifas.ufl.edu/programs/commorn/publications/desert-rose.PDF (2)http://www.bonsai-bci.com/species/adenium.html

8.05

no evidence