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

Eucalyptus caesia Benth.; silver princess, gungurru

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

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

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

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

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

y

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

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

6.04

Self-compatible or apomictic

y=1, n=-1

y

6.05

Requires specialist pollinators

y=-1, n=0

y

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

5

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

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:

0

Notes

Source

1.01

no evidence

1.02

no evidence

1.03

"Eucalyptus caesia is one of the best known eucalypts. There are two subspecies recognised; subsp. caesia and subsp. magna. The former is a small tree of about 6-9 metres in height while subsp. magna is a taller tree to about 15 metres with pendulous branches. This form is known in cultivation as "Silver Princess".

http://farrer.riv.csu.edu.au/ASGAP/e-cae.html

2.01

(1) Distribution: Granite outcrops in a restricted area in south Western Australia.
(2) USDA: 9b-11
(3) p.359 "31-32 S in latitude"

(1) http://farrer.riv.csu.edu.au/ASGAP/e-cae.html
(2) http://www.desert-tropicals.com/Plants/Myrtaceae/Eucalyptus_caesia.html
(3) Penfold, A. R. & J.L. Willis (1961) The eucalypts: botany, cultivation, chemistry, and utilization. Interscience Publishers , London, L. Hill; New York 1961. 551 pp.

2.02

2.03

(1) USDA: 9b-11
(2) p.120 "The extreme summer temperature may be 45 C at a number of placesin the area of distribution, and there may be an average of 16-26 days over 37.8C. The extreme winter temperaturemay be -3.9C with an average of 20-30 frosts." (3)Grows best with hot temperatures and low humidity. [vague information regarding habitat - restricted to granite outrcoppings in native habitat]

(1) http://www.desert-tropicals.com/Plants/Myrtaceae/Eucalyptus_caesia.html
(2) Chippendale, George McCartney (1973) Eucalypts of the Western Australian goldfields : (and the adjacent wheatbelt). Australian Government Publishing Service for the Minister for Primary Industry, Canberra 1973. 218 pp. (3)http://www.australiaplants.com/Eucalyptus_caesia_ssp_magna.htm

2.04

[subtropical] Distribution: Granite outcrops in a restricted area in south Western Australia.

http://farrer.riv.csu.edu.au/ASGAP/e-cae.html

2.05

(1)p.120 "It has been cultivated in most parts of Australia and also in California." (2)widely cultivated

(1)Chippendale, George McCartney (1973) Eucalypts of the Western Australian goldfields : (and the adjacent wheatbelt) / [by] G. M. Chippendale. Australian Government Publishing Service for the Minister for Primary Industry, Canberra 1973. 218 pp. (2)http://www.essencesonline.com/AusBushmain.htm

3.01

no evidence

3.02

no evidence

3.03

no evidence

3.04

no evidence

3.05

Bacon, P. (Project coordinator) (1997) An electronic atlas of weeds and invasive species.Version 1.0 May 1997. (Based on the original work "Holm, L.; J.V. Puncho; J.P. Herberger & D.L. Plucknett (1979) A Geographical Atlas of World Weeds. John Wiley & Sons, Inc." )

E. campageana, E. ferruginea, E. gracilis, E. marginata, E. miniata, e. pilularis, E. populnea, and E. tetradonta were listed as principal weeds in Australia (native habitat)

4.01

p. 119. no description of these traits

Chippendale, George McCartney (1973) Eucalypts of the Western Australian goldfields : (and the adjacent wheatbelt) / [by] G. M. Chippendale. Australian Government Publishing Service for the Minister for Primary Industry, Canberra 1973. 218 pp.

4.02

[chracteristic of the genus] " Eucalyptus monocultures are an environmental disaster, they are voracious, allelopathic and encourage the worst possible attitudes to land use and conservation."

http://gardenbed.com/source/27/2644_cul.asp

4.03

no evidence

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

4.04

Chemical properties of Eucalyptus deter grazing

http://www.ganesha.co.uk/Articles/Eucalyptus.htm

4.05

no evidence

4.06

Armillaria sp.: Australia
Botryosphaeria ribis: Australia [generalist]
Botrytis cinerea: Australia [generalist]
Phoma viminalis: Australia [specialist on another 2 Eucalyptus species, E. camaldulensis & E. leucoxylon; no known economic importance]

Farr, D.F., Rossman, A.Y., Palm, M.E., & McCray, E.B. (n.d.) Fungal Databases, Systematic Botany & Mycology Laboratory, ARS, USDA. Retrieved February 11, 2004, from http://nt.ars-grin.gov/fungaldatabases/

4.07

no evidence

4.08

[(1) a species adapt to frequent fire; (2) Eucalyptus forerst and are known for flammability, although the litters are flamable, climate and understory species also attribute to the fire.]
(1) In seasonally dry regions of the world fire is a recurring disturbance but little is known of how fire interacts with granite outcrop vegetation. We hypothesize that the floristic composition in granite vegetation, usually attributed to the edaphic environment, may also reflect the impact of disturbances such as fire. Dramatic differences in floristic composition and cover over 13 years and two fires were observed in vegetation on a Western Australian granite outcrop. This was very marked in the first year following the two fires, with annuals and geophytes showing the greatest turnover of species. Even among the perennial shrubs there was considerable turnover in a number of obligate seeders. After the first fire the number of species declined for woody perennials, herbaceous perennials and annuals, remained unchanged

(1) Yates, C. J.; Hopper, S. D.; Brown, A.; Leeuwen, S. van (2003) Impact of two wildfires on endemic granite outcrop vegetation in Western Australia. Journal of Vegetation Science, 2003, Vol.14, No.2, pp.185-194, many ref.
(2) Florence, R. G. (1996) Ecology and silviculture of eucalypt forests. CSIRO, Australia, Collingwood, Vic., Australia. 1996. 413 pp.

4.09

(1) Placement: Sun (2) Sun Exposure: Full sun

(1) http://www.australiaplants.com/Eucalyptus_caesia_ssp_magna.htm (2) http://www.desert-tropicals.com/Plants/Myrtaceae/Eucalyptus_caesia.html

4.1

p. 18 "It is adaptable to sand and sandy loams, and will grow in some clayey soils"

Kelly, Stan. (1969) Eucalypts. Text by G. M. Chippendale and R. D. Johnston. Nelson, Melbourne 1969

4.11

"Growth Habits: Small tree, 20 to 30 feet tall (6-9 m), with pendant branches; lignotuber"

http://www.desert-tropicals.com/Plants/Myrtaceae/Eucalyptus_caesia.html

4.12

p. 119 "Gungurru can be a mallee to about 20 ft high or a small trr to 30 ft high. It has a slender habit, with weeping branchlets and a fairly open crown"

Chippendale, George McCartney (1973) Eucalypts of the Western Australian goldfields : (and the adjacent wheatbelt) / [by] G. M. Chippendale. Australian Government Publishing Service for the Minister for Primary Industry, Canberra 1973. 218 pp.

5.01

p.120 " E. caesia is found naturally only on or around the base of some granite outcrops."

Chippendale, George McCartney (1973) Eucalypts of the Western Australian goldfields : (and the adjacent wheatbelt) / [by] G. M. Chippendale. Australian Government Publishing Service for the Minister for Primary Industry, Canberra 1973. 218 pp.

5.02

tree; Myrtaceae

5.03

no evidence

5.04

Small tree to 6m

http://members.iinet.net.au/~nursery/stockindex.htm

6.01

produce viable seeds in natural habitat

Chippendale, George McCartney (1973) Eucalypts of the Western Australian goldfields : (and the adjacent wheatbelt) / [by] G. M. Chippendale. Australian Government Publishing Service for the Minister for Primary Industry, Canberra 1973. 218 pp.

6.02

Propagation is from seed which germinates readily.

http://farrer.riv.csu.edu.au/ASGAP/e-cae.html

6.03

[artificial hybridization is possible, but no evidence concerning natural hybridization]
AB: The potential for interspecific hybridization within the genus Eucalyptus was investigated through controlled pollination and measurement of seedling leaf morphology. Eucalyptus gillii and E. socialis (subgen. Symphyomyrtus sect. Bisectae ser. Subulatae ) were used as the female parents, and pollen was sourced from 16 Eucalyptus species from a number of series within sections Bisectae (E. gillii, E. socialis, E. transcontinentalis, E. caesia subsp. caesia, E. macrocarpa, E. oldfieldii, E. orbifolia, E. websteriana, E. youngiana, E. kruseana, E. gardneri, E. eremophila and E. steedmanii ) and Adnataria (E. pruinosa, E. polyanthemos and E. sideroxylon ; subgen. Symphyomyrtus ). Thirty-four out of 36 crosses produced seeds; however, the percentage of seeds produced per flower pollinated varied considerably between crosses, as did germination percentage and seedling survival.

6.04

p. 193 Table 19.2 estimated outcrossing rate 0.62

6.05

(1) p.188 "It appears that pollination in all eucalypt species is effected by animal vectors, particularly insects. A number of species with very large flowers (more than 2 cm diameter) are considered to be predominatly pollinated by birds."
(2) The flowers are large (up to 50 mm in diameter) and normally pink to red in colour but white flowered plants are known. Flowering is very conspicuous and occurs in winter and spring. Flowers are followed by large, urn-shaped "gumnuts" about 30 mm in diameter.
(3) on the list of "Bird Attracting Plants"
(4) "Good for honey production"
(5) on the list of "Australian Plants That Attract Butterflies"(6)Pollination of Eucalyptus caesia by honeyeaters (Meliphagidae) [bird/mammal pollination syndrome (large, red/white, nectar rich), but also visited by insects]

(1) Eldridge, K. et al. (1993) Eucalypt domestication and breeding Oxford : Clarendon Press ; New York : Oxford University Press, 288 pp.
(2) http://farrer.riv.csu.edu.au/ASGAP/e-cae.html
(3) http://www.zanthorrea.com.au/gardening_info/Bird_Attracting_Plants.pdf
(4) http://www.nativenursery.com.au/catalog/product_info.php?products_id=128
(5) http://www.zoo.org.au/horticulture/imagedir/ausplants_butt.PDF (6)http://science.calm.wa.gov.au/papers/1975to9.php

6.06

p.150 "lignotuber seedlings can be very important in the regeneration of the eucalypt forest,..Indeed, the regeneration of many dry sclerophyll forests and woodlands may depend entirely on them."

6.07

"It is reported to bloom at 5 years age"

http://www.australiaplants.com/Eucalyptus_caesia_ssp_magna.htm

7.01

no evidence

7.02

p.120 "It has been cultivated in most parts of Australia and also in California."

Chippendale, George McCartney (1973) Eucalypts of the Western Australian goldfields : (and the adjacent wheatbelt) / [by] G. M. Chippendale. Australian Government Publishing Service for the Minister for Primary Industry, Canberra 1973. 218 pp.

7.03

no evidence

7.04

"Three samples had an average of 123 via ble seeds per gram of fertile and sterile seed."; "The weight of old fruits will sometimes bend branches"

(1) http://farrer.riv.csu.edu.au/ASGAP/e-cae.html
(2) http://www.australiaplants.com/Eucalyptus_caesia_ssp_magna.htm
(3) Chippendale, George McCartney (1973) Eucalypts of the Western Australian goldfields : (and the adjacent wheatbelt). Australian Government Publishing Service for the Minister for Primary Industry, Canberra 1973. 218 pp.

7.05

no evidence

7.06

dry fruit

7.07

no known means of attachment

7.08

no evidence of ingestion

8.01

(1) Flowers are followed by large, urn-shaped "gumnuts" about 30 mm in diameter.
(2) E. caesia ssp caesia, 83 viable seeds per gram, 88% germination. Dryandra WA. E. caesia ssp magna, 116 viable seeds per gram, 97% germination. Narrogin WA.
(3) "Three samples had an average of 123 via ble seeds per gram of fertile and sterile seed."; "The fruit is pendent, urn-shaped, 0.8-1.2 inch long and 0.7-1.0 inch wide."

(1) http://farrer.riv.csu.edu.au/ASGAP/e-cae.html
(2) http://www.australiaplants.com/Eucalyptus_caesia_ssp_magna.htm
(3) Chippendale, George McCartney (1973) Eucalypts of the Western Australian goldfields : (and the adjacent wheatbelt). Australian Government Publishing Service for the Minister for Primary Industry, Canberra 1973. 218 pp.

8.02

(1) "Seed will germinate in about two weeks."; "The weight of old fruits will sometimes bend branches"
(2) p.54 "Eucalypt seed which will remain viable only a short time in soil, probably no more than 6-12 month."; "The seed of euclypt is normally released from its woody capsule at the end of a seasonally dry period. Afire which scorcheds the crown of a eucalypt but does not burn the capsules may trigger a near total release of seed from a mature capsule crop soon after the fire." [characteristics of the genus]

(1) Chippendale, George McCartney (1973) Eucalypts of the Western Australian goldfields : (and the adjacent wheatbelt). Australian Government Publishing Service for the Minister for Primary Industry, Canberra 1973. 218 pp.
(2) Florence, R. G. (1996) Ecology and silviculture of eucalypt forests. CSIRO, Australia, Collingwood, Vic., Australia. 1996. 413 pp.

8.03

no evidence of being controlled

8.04

"The species develops a lignotuber and should respond to hard pruning to near ground level if rejuvenation is required. "

http://farrer.riv.csu.edu.au/ASGAP/e-cae.html

8.05

no evidence