Pacific Island Ecosystems at Risk (PIER)


Lagerstroemia indica


RISK ASSESSMENT RESULTS: Low risk, score: 6 (low risk based on second screen)


Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i.

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

Lagerstroemia indica L.; Lagerstroemia elegans, crape myrtle

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

y

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

1

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

y

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

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

y

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

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

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

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

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

y

6.07

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

See left

1

7.01

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

y=1, n=-1

y

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:

6

Supporting data:

Notes

Source

1.01

(1) Many of our most popular crapes myrtle varieties available for sale these days are hybrids obtained by crossing Lagerstroemia indica with L. fauriei or L. speciosa. The U.S. National Arboretum created a series of these hybrids known as the Indian Tribe group. These are noted for mildew resistance and improved hardiness and are named for native American tribes. 'Cherokee' is a shrubby variety with a loose open form and red flowers. 'Tuskegee' has a spreading form with dark pink flowers. 'Miami' blooms later in the season and also has dark pink flowers. 'Seminole, another later bloomer, has blossoms of medium pink. 'Tuscarora' is a rampant grower with orangy pink blooms, 'Potomac' is pink and 'Tonto' is very dark pink - and so on through an extensive palette.
(2) "More than 150 cultivars have been named, some formed from hybridization with other species." [many hybrids/cultivars developed, however the history of introduction is not long]

(1) http://www.floridata.com/ref/l/lager_i.cfm

(2) Whistler, A.W. (2000) Tropical Oramentals: a Guide. Timber Press, Inc., Portland, Oregon. 542pp. p.297

1.02

"Originally from Asia, crape myrtle has been naturalized throughout the United States as far north as Massachusetts"

http://www.floridata.com/ref/l/lager_i.cfm

1.03

no evidence

2.01

(1)Distributional range:
Native:
ASIA-TEMPERATE
China: China - Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Yunnan, Zhejiang
ASIA-TROPICAL
Indo-China: Indochina; Thailand
Indian Subcontinent: Nepal
(2)Lagerstroemia indica is indigenous to China

2.02

List of countries with natural populations
Asia
[China] Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Yunnan, Zhejiang
Indochina
Nepal
Thailand [Natural range is primarily temperate although it is grown in some more tropical environments]

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://wpsm.net/Lagerstromia.pdf

2.03

(1) Harrdiness Range 7A to 9A, (2) "Originally from Asia, crape myrtle has been naturalized throughout the United States as far north as Massachusetts" (3) Drought resistant once established

(1) Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7. (2) http://www.floridata.com/ref/l/lager_i.cfm (3)http://www.pnc.com.au/~wbrouwer/lagerstroemia.htm

2.04

List of countries with natural populations
Asia
[China] Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Yunnan, Zhejiang
Indochina
Nepal
Thailand [Natural range is primarily temperate although it is grown in some more tropical environments]

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

2.05

" First introduced to England and the United States in the eighteenth century, crape myrtle is now widely cultivated throughout the world. "

http://www.floridata.com/ref/l/lager_i.cfm

3.01

"Originally from Asia, crape myrtle has been naturalized throughout the United States as far north as Massachusetts"

http://www.floridata.com/ref/l/lager_i.cfm

3.02

"They are enthusiastic reseeders so you may find yourself pulling up baby crapes throughout the summer" [reference is vague about the extent of the problem; no other references found to implicate as a garden or lawn weed]

http://www.floridata.com/ref/l/lager_i.cfm

3.03

no evidence

3.04

On the list of "invasive plants affecting natural areas in the U.S. " [the source of the information is personal communication and is dubious - species that are listed on this webpage may be naturalized but often they do not meet the criteria for being environmental weeds]

http://www.nps.gov/plants/alien/list/l.htm

3.05

no evidence

4.01

no description of these traits

http://www.floridata.com/ref/l/lager_i.cfm

4.02

no evidence

4.03

no evidence

4.04

Palatable Browse Animal: Low
Palatable Graze Animal: Low

USDA, NRCS. 2002. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

4.05

no evidence

4.06

(1) [generalist insect pests; specialist fungal diseases; no major economic pests]
Pests and Diseases
Pests: Aphids often infest the new growth causing an unsightly sooty mold to grow on the foliage. Heavy infestations can be serious. Ambrosia beetle can attack even healthy trees; they tend to attack as trees emerge from dormancy. Wax scale.
Diseases: As a group, the L. indicas are very susceptible to powdery mildew compared to the hybrids and L. fauriei 'Fantasy'. Powdery mildew can severely affect Crapemyrtle. Leaf spots are only a minor concern and do not require treatment.
(2) [a prefered food plant of a polyphagus leafhopper which transfer phony peach disease] "AB: Feeding-site acceptance and adult survival of the cicadellids Homalodisca coagulata and H. insolita, vectors of phony peach disease (PPD), were determined when field-collected leafhoppers were introduced into cages placed on branches of infected and uninfected peach, var. Flordaking. The abundance and seasonal fluctuations of H. coagula

(1) Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7.
(2) Mizell, R. F.; French, W. J. (1987) Leafhopper vectors of phoney peach disease: feeding site preference and survival on infected and uninfected peach, and seasonal response to selected host plants. Journal of Entomological Science, 1987, Vol.22, No.1, pp.11-22, 23 ref.
(3) Farr, D.F., Rossman, A.Y., Palm, M.E., & McCray, E.B. (n.d.) Fungal Databases, Systematic Botany & Mycology Laboratory, ARS, USDA. Retrieved January 27, 2004, from http://nt.ars-grin.gov/fungaldatabases/

4.07

"This plant is considered mostly allergy free and causes little or no allergy problems in most people. "

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

4.08

Low flammability, deciduous, no other evidence suggests creating a fire hazard

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

4.09

(1) Exposure Full sun
(2) Shade Tolerance: Intolerant

(1) Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7.
(2) USDA, NRCS. 2002. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

4.1

(1) Soil Condition Loamy, sandy, clay, acidic, neutral, slightly alkaline, tolerates some salt, drought tolerant
(2) Adapted to Coarse Textured Soils: Yes; Adapted to Fine Textured Soils: No; Adapted to Medium Textured Soils: Yes (3)They tolerate clay and alkaline soil well.

(1) Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7.
(2) USDA, NRCS. 2002. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA. (3)http://edis.ifas.ufl.edu/ST342

4.11

tree

4.12

no evidence

5.01

terrestrial

5.02

tree; Lythraceae

5.03

no evidence

5.04

Deciduous tree 20 - 25 ft.

6.01

no evidence

6.02

"They are enthusiastic reseeders so you may find yourself pulling up baby crapes throughout the summer"

http://www.floridata.com/ref/l/lager_i.cfm

6.03

"Many of our most popular crapes myrtle varieties available for sale these days are hybrids obtained by crossing Lagerstroemia indica with L. fauriei or L. speciosa. The U.S. National Arboretum created a series of these hybrids known as the Indian Tribe group." [many artificial hybrids developed, however no known evidence of natural hybridization]

http://www.floridata.com/ref/l/lager_i.cfm

6.04

In both L. indica (an ornamental shrub) and L. parviflora (a tree used for timber), pollen tube growth was studied following self and cross pollinations. Tubes grew normally for the entire length of the style in cross pollinated flowers of both species, but in selfed flowers they reached only the middle part of the style before their tips swelled and they ceased to grow. The inhibition of pollen tubes in the style suggested that a gametophytic self incompatibility system acts in both species.

Sareen, T. S.; Kaur, J. (1991) Self-incompatibility system in Lagerstroemia parviflora Roxb. and L. indica Linn. Plant Cell Incompatibility Newsletter, 1991, No. 23, pp. 58-62, 11 ref.

6.05

visited by bees

http://www.ces.uga.edu/pubcd/b1106-w.html

6.06

Some trees sprout from the base of the trunk and roots [common root suckers allow spread by vegetative fragmentation]

http://edis.ifas.ufl.edu/ST342

6.07

"In a warm greenhouse, such seedlings will make rapid growth, and often bloom the first summer from a December or January sowing."

http://wpsm.net/Lagerstromia.pdf

7.01

[a roadside tree producing many tiny, wind dispersed seeds that will follow vehicles]
(1) "The following species are proposed as the main roadside trees: Lagerstroemia indica, Choerospondias axillaris, Cercis chinensis, Sassafras tzumu, Livistona chinensis, Bischofia javanica, Photinia serrulata, Machilus thunbergii [Persea thunbergii ], Casuarina equisetifolia ." (2) "fruit maturing in fall, a round woody capsule splitting and liberating tiny winged seeds"

(1) Hang, JinSheng; Lin, LiHua; Chen, Ce; Shao, QingSong (2003) Current situation and tentative distribution idea of road side tree in Wenzhou City. Journal of Zhejiang Forestry Science and Technology, 2003, Vol.23, No.2, pp.76-79, 7 ref.
(2) http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/maritime/Lagerin.htm

7.02

"Originally from Asia, crape myrtle has been naturalized throughout the United States as far north as Massachusetts"

http://www.floridata.com/ref/l/lager_i.cfm

7.03

no prodcucts

7.04

"fruit maturing in fall, a round woody capsule splitting and liberating tiny winged seeds"

http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/maritime/Lagerin.htm

7.05

no evidence

7.06

"fruit a globose capsule"

Whistler, A.W. (2000) Tropical Oramentals: a Guide. Timber Press, Inc., Portland, Oregon. 542pp. p.297

7.07

no evidence

7.08

no evidence of ingestion

8.01

(1) "Viable seeds/kg : 50000 - 100000"
(2) "Each capsule contains 20 or more winged seeds. Seeds are 7 to 11 mm long"; "Spectacular flowering is the trait that most often justifies use of crape-myrtles as landscape plants. The red, white, pink, or purple flowers, each 1.5 to 5.0 cm in diameter, are produced in 12- to 44-cm-long tapered panicles, each comprising 25 to 500 flowers." [need less than 50 fruits per square meter, which could be attained by a single flowering branche]

(1) http://www.worldagroforestrycentre.org/Sites/TreeDBS/TSSD/seedinfo.cfm?seed_id=lagind
(2) http://wpsm.net/Lagerstromia.pdf

8.02

no evidence of dormancy "Egolf and Andrick (1978) reported that without stratification, seeds sown at 15 degree C germinated within 10 days."

http://wpsm.net/Lagerstromia.pdf

8.03

Basagran (bentazon) application caused foliar injury on Crape Myrtle [susceptible to herbicide that is meant to be specific to nutsedges (Cyperaceae)]

http://www.clemson.edu/hort/sctop/csec/csec-04.htm

8.04

Pruning methods vary from topping to cutting Crape-Myrtle nearly to the ground each spring. Severe pruning or topping can stimulate basal sprouting which can become a constant nuisance.

http://edis.ifas.ufl.edu/ST342

8.05

Powdery mildew can severely affect Crape-Myrtle.

http://edis.ifas.ufl.edu/ST342


Need more info? Have questions? Comments? Information to contribute? Contact PIER!


[ Return to PIER homepage ] [Risk assessment page]


This page updated 2 November 2005