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

Grewia occidentalis (Lavender star flower, Buttonwood, cross berry, four corners)

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

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

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

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

n

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

2

7.01

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

y=1, n=-1

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

n

7.05

Propagules water dispersed

y=1, n=-1

n

7.06

Propagules bird dispersed

y=1, n=-1

y

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

y

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

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:

-3

Notes

Source

1.01

No evidence

1.02

No evidence

1.03

No evidence

2.01

(1)Country of Origin: Africa (2)The natural distribution of the Grewia occidentalis ranges from the Western Cape up to Zimbabwe and Mozambique. (3)South Africa north to Zimbabwe

(1)http://florawww.eeb.uconn.edu/acc_num/198500635.html (2)http://www.plantzafrica.com/plantefg/grewiaoccident.htm (3)Whistler, W.A. 2000 Tropical Ornamentals. Timber Press, Portland, OR

2.02

Introduced to Hawaii

http://www.hear.org/starr/hiplants/images/thumbnails/html/grewia%20occidentalis_thumbnails.htm

2.03

(1)USDA: 9,10 (2)This attractive indigenous shrub may be found in a variety of habitats ranging from arid karoo, coastal dune bush, evergreen montane forest and wooded grasslands. (3)Cross-berry occurs on forest margins, in riverine bush and in open bushveld and thickets. In the highveld and Drakensberg areas of South Africa, this shrub prefers areas of high moisture where it grows singly in protected positions amongst other trees, along rivers and streams and on the edges of wooded areas. It can also be found in sheltered and even drier, exposed places on rocky slopes. On the KwaZulu-Natal coast and midlands, Grewia occidentalis can be found on the edge of low-lying, dune and scrap forest. It is also found in the rocky outcrops in the woodland of the bushveld-savannah and along rivers. Coastal Forest
In this vegetation type which is confined to a narrow belt with high dunes and Dune Forest, the shrubs and scramblers are particularly important to stabalise sand. Grewia occidentalis grows in this area with o

(1)http://www.desert-tropicals.com/Plants/Tiliaceae/Grewia_occidentalis.html (2)http://www.plantzafrica.com/plantefg/grewiaoccident.htm (3)http://www.ecoport.org/EP.exe$EntNameSrc

2.04

(1)Country of Origin: Africa (2)The natural distribution of the Grewia occidentalis ranges from the Western Cape up to Zimbabwe and Mozambique.

(1)http://florawww.eeb.uconn.edu/acc_num/198500635.html (2)http://www.plantzafrica.com/plantefg/grewiaoccident.htm

2.05

(1)Introduced to Hawaii (2)Widely cultivated in the tropics

(1)http://www.hear.org/starr/hiplants/images/thumbnails/html/grewia%20occidentalis_thumbnails.htm (2)Whistler, W.A. 2000 Tropical Ornamentals. Timber Press, Portland, OR

3.01

No evidence

3.02

The root system is not aggressive and can therefore be planted near buildings and paving.

http://www.plantzafrica.com/plantefg/grewiaoccident.htm

3.03

No evidence

3.04

No evidence

3.05

(1) "During trials in 1984 at Northern Cape, application from the air of 0-70 kg/ha ethidimuron controlled many bush and tree species including Grewia flava, Rhigozum trichotomum, Boscia albitrunca and, in particular, Acacia mellifera and A. erioloba." [this is a native woody plant that encroaches on pastures] (2)Grewia asiatica: Becoming widespread in northern Queensland, Australia. [could not find any evidence that it is an economic weed in Queensland]

(1)Fourie, M. P. (1992) Chemical bush control with ethidimuron. Proceedings of the 1st International Weed Control Congress., 1992, No. 2, pp. 166-168, 14 ref. (2)http://www.hear.org/pier/species/grewia_asiatica.htm

4.01

No evidence of such structures.

http://www.plantzafrica.com/plantefg/grewiaoccident.htm

4.02

No evidence

4.03

http://www.omnisterra.com/bot/pp_home.cgi?name=Grewia+occidentalis+&submit=Submit+Query&search=all

4.04

(1)Leaves are browsed by cattle, goats and game (black rhino, giraffe, nyala and grey duiker. (2) 'Nguni goats and Boer goats, which are farmed together in the savannas of the Eastern Cape Province, depend on the same feed resources. The feeding height intake rates and preferences of one of their most preferred browse species, Grewia occidentalis L. (Tiliaceae), were studied in order to indirectly determine resource partitioning between these goat breeds on the basis of feeding height....'

(1)http://www.plantzafrica.com/plantefg/grewiaoccident.htm (2) The feeding height preferences of two goat breeds fed Grewia occidentalis L. (Tiliaceae) in the Eastern Cape, South Africa. Dziba, LE; Scogings, PF; Gordon, IJ; Raats, JG. Small ruminant research : the journal of the International Goat Association. Jan 2003. v. 47 (1) p. 31-38

4.05

No evidence

4.06

This site lists the following fungi to be associated with G. occidentalis:
Asterina delicata: Southern Africa - 8029, 34234
Phyllachora grewiae: Southern Africa - 8029
Ramularia grewiae-occidentalis: South Africa - 34234
Ravenelia atrides: Southern Africa - 8029, 34234

http://nt.ars-grin.gov/fungaldatabases/all/FindRecOneFungusFrame.cfm

4.07

No evidence

4.08

ENVIRONMENTAL HAZARDS: NONE

http://www.ornamentalworld.com/Guide2.asp?PLANTID=0010960-0000

4.09

(1)Grewia occidentalis need full sun and intermediate temperatures. (2)Sun Exposure: Full sun (3)Good indoors [implies tolerance of low light] (4)Very adaptable to most lighting conditions (5)semi shade

(1)http://www.plantoftheweek.org/week151.shtml (2)http://www.desert-tropicals.com/Plants/Tiliaceae/Grewia_occidentalis.html (3)http://www.bonsaiboy.com/catalog/product337.html (4)Whistler, W.A. 2000 Tropical Ornamentals. Timber Press, Portland, OR (5)http://www.blnn.org.za/Trees%20lists.htm

4.1

Soil: Clay, loam or sand

http://www.geocities.com/RainForest/1079/grewiaoc.html

4.11

a large evergreen shrub, small tree, or sprawling climber [weak climber]

http://www.almostedenplants.com/mall/Fourcorners.asp

4.12

No evidence

5.01

(1)is an evergreen shrub or small tree that will reach about 9 feet in nature. (2)It is a scrambling deciduous shrub or small tree reaching up to 3m in height

(1)http://www.plantoftheweek.org/week151.shtml (2)http://www.plantzafrica.com/plantefg/grewiaoccident.htm

5.02

Tiliaceae

5.03

Tiliaceae

5.04

Shrub

6.01

Purple star-shaped flowers (measuring 1.5 to 3cm across) appear in summer (October - January), followed by distinctive four-lobed fruits (hence the common name cross-berry and four-corner). Fruits turns shiny reddish-brown to light purple when ripe (January - May) and may remain on the tree for long periods.

http://www.plantzafrica.com/plantefg/grewiaoccident.htm

6.02

Grewia occidentalis is propagated by cutting of new growth in spring or by seed. Seed germinate in 14-21 days at 70° F.

http://www.plantoftheweek.org/week151.shtml

6.03

No evidence

6.04

'Grewia occidentalis flowers are monomorphie, protandrous and dichogamous, the latter being complete. The flowers are self-incompatible and the pollen-ovule ratio of 8664:1 is indicative of a xenogamous species with relatively inefficient pollen transfer. ...'

TI: REPRODUCTIVE BIOLOGY OF GREWIA-OCCIDENTALIS L. TILIACEAE. AU: ZIETSMAN-P-C {a} SO: South-African-Journal-of-Botany. 1991; 57 (6): 348-351..

6.05

'… G. occidentalis is pollinated by Apis mellifera and two species of Xylocopa. Pollinator availability appears not to have an adverse effect on seed set. The behavioral pattern of most of the honey-bees on the flowers is such that pollination does not take place during the majority of visits....'

TI: REPRODUCTIVE BIOLOGY OF GREWIA-OCCIDENTALIS L. TILIACEAE. AU: ZIETSMAN-P-C {a} SO: South-African-Journal-of-Botany. 1991; 57 (6): 348-351..

6.06

Grewia occidentalis is propagated by cutting of new growth in spring or by seed. Seed germinate in 14-21 days at 70° F. [no natural vegetative reproduction]

TI: REPRODUCTIVE BIOLOGY OF GREWIA-OCCIDENTALIS L. TILIACEAE. AU: ZIETSMAN-P-C {a} SO: South-African-Journal-of-Botany. 1991; 57 (6): 348-351..

6.07

(1)GROWTH RATE: MEDIUM (2)Fast growing evergreen [minimum estimate for a fast growing small shrub]

(1)http://www.ornamentalworld.com/Guide2.asp?PLANTID=0010960-0000 (2)http://www.cvwd.org/lush&eff/lsh&ef44.htm

7.01

The ripe fruits have a sweet fruity taste and are eagerly eaten by humans. [seeds may be discarded]

http://www.ecoport.org/

7.02

(1)Grown as an ornamental (2)In certain areas where the sugar content of the fruits is high, they are collected and dried for later use. The dried fruits are sometimes boiled in milk - a bush milkshake! Beer is also brewed from the ripe fruit in certain areas. Other human uses of this species include using the wood to make bows and spear shafts.

(1)http://www.plantoftheweek.org/week151.shtml (2)http://www.plantzafrica.com/plantefg/grewiaoccident.htm

7.03

Seeds probably are not very small - species not a major trade speceis.

7.04

Ripe fruits are relished by various birds such as louries, mousebirds, bulbuls and barbets as well as certain mammals (including man).

http://www.plantzafrica.com/plantefg/grewiaoccident.htm

7.05

Ripe fruits are relished by various birds such as louries, mousebirds, bulbuls and barbets as well as certain mammals (including man).

http://www.plantzafrica.com/plantefg/grewiaoccident.htm

7.06

Ripe fruits are relished by various birds such as louries, mousebirds, bulbuls and barbets as well as certain mammals (including man).

http://www.plantzafrica.com/plantefg/grewiaoccident.htm

7.07

No evidence of any means of attachment.

7.08

Studies have shown that seed which has passed through the gut of monkeys and baboons germinates better than those collected from a tree. This is due to the fact that the seeds chemical inhibitors have been broken down by the animal's stomach acids.

http://www.plantzafrica.com/plantefg/grewiaoccident.htm

8.01

(1)distinctive four-lobed fruits (hence the common name cross-berry and four-corner). Fruits turns shiny reddish-brown to light purple when ripe (January - May) and may remain on the tree for long periods. (2)Large seeds - 360 per oz.

(1)http://www.plantzafrica.com/plantefg/grewiaoccident.htm (2)http://www.carterseeds.com/FGH%20SEEDS.htm

8.02

(1)distinctive four-lobed fruits (hence the common name cross-berry and four-corner). Fruits turns shiny reddish-brown to light purple when ripe (January - May) and may remain on the tree for long periods. the fact that the seeds chemical inhibitors have been broken down by the animal's stomach acids. However germination is generally fairly good (2)Seed germinate in 14-21 days at 70° F.

(1)http://www.plantzafrica.com/plantefg/grewiaoccident.htm (2)http://www.plantoftheweek.org/week151.shtml

8.03

No evidence that the species is being controlled for.

8.04

Grewia makes a good espalier against a warm wall. Prune as needed for espaliers and hedges. Needs very frequent pruning to keep it as a neat clipped hedge. Often trained on a trellis or against a wall.

http://www.geocities.com/RainForest/1079/grewiaoc.html

8.05

Don’t know