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

Callistemon rigidus; stiff bottlebrush

Answer

1.01

synonyms: Crescentia pinnata Jacq.; Kigelia pinnata (Jacq.) DC.

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

y

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

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

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

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

y

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

n

6.07

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

See left

3

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

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:

1

Notes

Source

1.01

no evidence

1.02

no evidence

1.03

no evidence

2.01

(1)Native: AUSTRALASIA , Australia: Australia - New South Wales (2)Tree of Queensland, Australia [tropical]

(1)USDA, ARS, National Genetic Resources Program.
Germplasm Resources Information Network - (GRIN) [Online Database].
National Germplasm Resources Laboratory, Beltsville, Maryland.
URL: http://www.ars-grin.gov/var/apache/cgi-bin/npgs/html/tax_search.pl?Callistemon+rigidus (19 January 2004) (2)http://www.forests.qld.gov.au/qts/treetext.html

2.02

2.03

(1)USDA hardiness zones: 9 through 11 (2)damp places, low elevation [Australia] (3)Very useful shrub in wet conditions

(1)http://hort.ifas.ufl.edu/shrubs/CALRIGA.PDF (2)http://www.hcmt.org.au/pubs/Bushland_Resource_Kit/HBRK_native_list.pdf (3)http://www.forests.qld.gov.au/qts/treetext.html

2.04

Native: AUSTRALASIA Australia: Australia - New South Wales [Queensland]

USDA, ARS, National Genetic Resources Program.
Germplasm Resources Information Network - (GRIN) [Online Database].
National Germplasm Resources Laboratory, Beltsville, Maryland.
URL: http://www.ars-grin.gov/var/apache/cgi-bin/npgs/html/tax_search.pl?Callistemon+rigidus (19 January 2004)

2.05

(1) Hawaii, (2) Hong Kong, (3) Nigeria, (4) Kenya

(1) Neal, M.C. (1965) In Gardens of Hawaii. Bernice p. Bishop Museum Special Publicatio 50. Bishop Museeum Press, Honolulu. 924pp. p. 643
(2) http://www.hktree.com/tree/Stiff_Bottle-brush.htm
(3) Isiaka, A. O.; Nureni, O. O.; Adeleke, A. K.; Ekundayo, O.; Wilfried, A. K. (2002) Chemical composition of the leaf essential oil of Callistemon rigidus R. Br. growing in Nigeria. Journal of Essential Oil-Bearing Plants, 2002, Vol. 5, No. 2, pp. 55-59, 9 ref.
(4) Omunyin, M. E.; Wabule, M. N. (1996) Occurrence of African mistletoe Erianthemum ulugurense on Toona ciliata and other trees in Kenya. Plant Disease, 1996, Vol. 80, No. 7, pp. 823, 1 ref.

3.01

no evidence

3.02

no evidence

3.03

no evidence

3.04

on a list of Australian species that may become invasive in Wimmera, Australia [no evidence]

http://home.vicnet.net.au/~wgapinc/MayBeInvasive.htm

3.05

no evidence

4.01

leaves of this shrub are sharply pointed

http://hort.ifas.ufl.edu/shrubs/CALRIGA.PDF

4.02

no evidence

4.03

no evidence

4.04

don't know [sharp leaves]

4.05

no evidence

4.06

(1) AB: C. colhounii was isolated from diseased Callistemon rigidus in Florida, USA, and pathogenicity was confirmed. C. colhounii was also isolated from diseased Gaultheria procumbens in a nursery in Oregon, USA. (a pathogen of concern)
(2) Host range of Cylindrocladium colhounii
Callistemon rigidus: FL - 32068
Centrosema acutifolium: Colombia - 5833, 25570; Costa Rica - 5833
Centrosema brasilianum: Colombia - 5833
Centrosema macrocarpum: Colombia - 5833; Costa Rica - 5833
Centrosema pubescens: Colombia - 5833; Costa Rica - 5833
Gaultheria procumbens: OR - 32068
Phellodendron amurense: Japan - 30191
Cylindrocladium colhounii var. colhounii
Arachis pintoi: Australia - 8285
Camellia sinensis: Mauritius - 8285
Canavalia ensiformis: India - 8285
Carya sp.: VA - 8285
Centrosema sp.: Colombia - 8285
Ficus carica: LA - 8285
Pinus strobus: NC - 8285
Cylindrocladium colhounii var. macroconidialis
Eucalyptus grandis: South Africa - 8285

(1) El-Gholl, N. E.; Schubert, T. S.; Walker, S. E. (1997) Expanded range of Cylindrocladium colhounii in the United States. Plant Disease, 1997, Vol. 81, No. 11, pp. 1333, 4 ref.
(2) http://nt.ars-grin.gov/fungaldatabases/all/FindRecOneFungusFrame.cfm

4.07

no evidence

4.08

Evergreen plant of wet habitats [not likely a fire hazard]

http://www.hcmt.org.au/pubs/Bushland_Resource_Kit/HBRK_native_list.pdf

4.09

Sun Exposure: Full Sun

http://plantsdatabase.com/go/2331/index.html

4.1

(1)Soil tolerances: acidic; alkaline; sand; loam (2)light, loamy or sandy soil.

(1)http://hort.ifas.ufl.edu/shrubs/CALRIGA.PDF (2)http://www.greengold.com.au/greengold/CARENOTES/CARENOTES/calliste.htm

4.11

shrub

http://hort.ifas.ufl.edu/shrubs/CALRIGA.PDF

4.12

no evidence

5.01

terrestrial

5.02

shrub; Myrtaceae

5.03

no evidence

5.04

shrub

6.01

no evidence

6.02

Propagation Methods:
From semi-hardwood cuttings
From seed; direct sow after last frost

http://plantsdatabase.com/go/2331/index.html

6.03

The RHS lists some 25 species of low shrubs and trees in the genus and easy interspecific hybridization has led to some confusion in “what is what” in the Callistemon world. Dirr lists six species and comments on the difficulties in taxonomy and identification. ...'

http://arboretum.sfasu.edu/plants/callistemoncitrinusvarlinearis/Default.htm

6.04

no evidence

6.05

This plant is attractive to bees, butterflies and/or birds [with generalist bird poliination syndrome, but may also be pollinated by insects]

http://plantsdatabase.com/go/2331/index.html

6.06

no evidence

6.07

(1)Moderately fast growing (2)Growth rate: moderate [minimum estimate for a moderate growth rate large shrub]

(1)http://kleberg-tx.tamu.edu/masterg/calendar/plantsale.htm (2)http://hort.ufl.edu/shrubs/CALRIGA.PDF

7.01

small seed but no known structure of attachment

http://farrer.riv.csu.edu.au/ASGAP/callistn.html#prop

7.02

an oramental

7.03

no evidence

7.04

Following flowering, three-celled woody seed capsules develop with each capsule containing many small seeds. [very small seeds also shown on the picture]

http://farrer.riv.csu.edu.au/ASGAP/callistn.html#prop

7.05

Grows in Riparian & Freshwater Wetland (seasonal) [the tiny seeds and woody capsules are assumed to float]

http://home.vicnet.net.au/~wgapinc/MayBeInvasive.htm

7.06

dry fruit

7.07

no evidence

7.08

no evidence of ingestion

8.01

Following flowering, three-celled woody seed capsules develop with each capsule containing many small seeds. [very small seeds also shown on the picture]

http://farrer.riv.csu.edu.au/ASGAP/callistn.html#prop

8.02

"The woody seed capsules form close cylinders around the stem and remain there for two years or more." [seed bank must be in soil]

http://www.butterflies.org/hortcltr3.cfm?plantID=36

8.03

no evidence

8.04

(1) "Bottlebrush is known to be difficult to transplant as a large specimen."
(2) Responds well to pruning.

(1) http://hort.ifas.ufl.edu/shrubs/CALRIGA.PDF (2) http://www.forests.qld.gov.au/qts/treetext.html

8.05

no evidence