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

Crassula ovata (Mill.) Druce (Crassula argenta; jade plant)

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

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

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

y

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

n

4.05

Toxic to animals

y=1, n=0

n

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

n

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

y

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

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

6.04

Self-compatible or apomictic

y=1, n=-1

6.05

Requires specialist pollinators

y=-1, n=0

n

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

y

6.07

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

See left

4

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

7.05

Propagules water dispersed

y=1, n=-1

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

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

n

8.05

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

y=-1, n=1

Total score:

-4

Notes

Source

1.01

No evidence

1.02

Single localized collection at Hanapepe, Hawai‘i (Kauai)

http://ravenel.si.edu/botany/pacificislandbiodiversity/hawaiianflora/ManualSupplement3.1.pdf

1.03

No evidence

2.01

Origin: South Africa (Eastern Cape)

http://www.desert-tropicals.com/Plants/Crassulaceae/Crassula_argentea.html

2.02

2.03

(1)Hardiness:
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)
USDA Zone 11: above 4.5° C (40° F)
(2) Hardiness Range 10A to 11 (3)natural habitat on dry hillsides under the blazing South African sun

(1) http://plantsdatabase.com/go/9/ (2) Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7. (3)http://www.jadeplants.co.nz/

2.04

Origin: South Africa (Eastern Cape)

http://www.desert-tropicals.com/Plants/Crassulaceae/Crassula_argentea.html

2.05

(1)Introduced to Phoenix (U.S). (2)Introduced to south part of the U.S. (3)It has been spread all around the world.

(1)http://www.desert-tropicals.com/Plants/Crassulaceae/Crassula_argentea.html (2)http://home.tiscali.nl/fuchsiaweb/herbarium/crassulaovata.html (3)http://www.bihrmann.com/rikke/subs/cra-ova-sub.asp

3.01

Single localized collection at Hanapepe, Hawai‘i (Kauai)

http://ravenel.si.edu/botany/pacificislandbiodiversity/hawaiianflora/ManualSupplement3.1.pdf

3.02

No evidence

3.03

No evidence

3.04

No evidence

3.05

Crassula helmsii is considered an invasive weed and subjected to control

Dawson, F. H. (1996) Crassula helmsii: attempts at elimination using herbicides. Hydrobiologia, 1996, Vol. 340, No. 1/3, pp. 241-245, 5 ref.

4.01

No evidence

http://www.desert-tropicals.com/Plants/Crassulaceae/Crassula_argentea.html

4.02

No evidence

4.03

No evidence

http://www.omnisterra.com/bot/pp_home.cgi

4.04

Sub-tropical thicket is a very palatable and nutritious veld type and as a result, where it occurs (or in close proximity) is where the visitor is likely to see the most game {C. ovata is a prominent part of this habitat type]

http://www.baviaans.net/wildlife_4.html

4.05

No evidence

4.06

Oidium sp was listed to be associated with this plant.
fungi associated with Crassula argentea
Alternaria sp.: FL
Armillaria mellea: CA [generalist]
Ascochyta sp.: FL
Bipolaris sp.: FL
Cercospora sp.: FL
Corynespora sp.: FL
Cylindrocladium pteridis: FL [generalist]
Diplodia sp.: FL
Fusarium sp.: FL
Phyllosticta sp.: FL
Pythium sp.: FL
Rhizoctonia solani: FL [generalist]
Stemphylium bolickii: FL [a recognized pest for ornamental Crassulaceae plant species (2) but not considered economically important]

(2) http://www.apsnet.org/online/common/names/kalancho.asp

4.07

No evidence

4.08

(1)a succulent shrub (2)Evergreen

(1)http://www.desert-tropicals.com/Plants/Crassulaceae/Crassula_argentea.html (2)Horticopia A to Z CD-ROM database.

4.09

(1)Sun Exposure: Full Sun (2)prefers full shade to partial shade or partial sun (3)Exposure Full shade (4)partial shade

(1)http://plantsdatabase.com/go/9/ (2)http://www.horticopia.com/hortpix/html/pc1747.htm (3)Horticopia A to Z. CD-ROM database. (4)http://davesgarden.com/t/371951

4.1

(1)Soil pH requirements: 6.1 to 6.5 (mildly acidic) (2)soil should be dry (3)Loamy, sandy, acidic, neutral, slightly alkaline, tolerates salt, drought tolerant, humidity intolerant (4)well-drained soil

(1)http://plantsdatabase.com/go/9/ (2)http://www.horticopia.com/hortpix/html/pc1747.htm

4.11

Not a climber - a succulent shrub

http://www.desert-tropicals.com/Plants/Crassulaceae/Crassula_argentea.html

4.12

No evidence

5.01

Cacuts/Succulent in Crassulaceae

http://plantsdatabase.com/go/9/

5.02

Growth Habits: Succulent shrub, the wild variety can reach 9 feet (2.7 m) when planted outside

http://www.desert-tropicals.com/Plants/Crassulaceae/Crassula_argentea.html

5.03

5.04

6.01

No evidence

6.02

Can easy be reproduced by leaves, cuttings and seeds.

http://www.bihrmann.com/rikke/subs/cra-ova-sub.asp

6.03

No evidence

6.04

No evidence

6.05

Photo of flowers - generalist insect

http://plantsdatabase.com/showpicture/11822/

6.06

(1)Propagation: Stem cuttings, leaf cuttings (2)New plants from dropped, broken leaves

(1)http://www.desert-tropicals.com/Plants/Crassulaceae/Crassula_argentea.html (2)http://www.bcss-liverpool.pwp.blueyonder.co.uk/Growing_Crassula_ovata.htm

6.07

"From this I assume that the conditions in the greenhouse are those required for flowering, once the plant is about four years old and about 12 inches tall."

http://www.bcss-liverpool.pwp.blueyonder.co.uk/Growing_Crassula_ovata.htm

7.01

Probably not - not an avenue species, nor does it inhabit areas around agricultural farms.

7.02

This plant is suitable for growing indoors, suitable for xeriscaping

http://plantsdatabase.com/go/9/

7.03

No evidence regarding seed morphology.

7.04

Tentative observations show that most cliff-dwelling succulent species have wind-dispersed seed, with water action also playing a role in others. [refers to S. African Crassula and succulents in general]

http://www.succulents.net/society/aloe_37.html

7.05

Tentative observations show that most cliff-dwelling succulent species have wind-dispersed seed, with water action also playing a role in others. [refers to S. African Crassula]

http://www.succulents.net/society/aloe_37.html

7.06

Genus characteristic - fruit is a follicle with 1 to 12 seeds per folicle. No further evidence regarding seed morphology.

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1999. Manual of the flowering plants of Hawai`i. Revised edition. University of Hawai`i Press, Honolulu.

7.07

no means of attachment

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1999. Manual of the flowering plants of Hawai`i. Revised edition. University of Hawai`i Press, Honolulu.

7.08

no evidence of consumption

8.01

Genus characteristic - fruit is a follicle with 1 to 12 seeds per folicle [boderline based on photos of plants in full bloom]

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1999. Manual of the flowering plants of Hawai`i. Revised edition. University of Hawai`i Press, Honolulu.

8.02

no evidence

8.03

no evidence

8.04

(1) "growth is very slow" (2) Pruning done annually [not frequent]

(1)Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7. (2)http://www.bcss-liverpool.pwp.blueyonder.co.uk/Growing_Crassula_ovata.htm#Pruning/Taking%20Cuttings

8.05

Don’t know.