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

Yucca guatemalensis Baker (syn. Yucca elephantipes); spineless yucca, bluestem yucca

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

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

2

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

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

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

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

4.05

Toxic to animals

y=1, n=0

n

4.06

Host for recognized pests and pathogens

y=1, n=0

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

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

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

4

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

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

7.08

Propagules survive passage through the gut

y=1, n=-1

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

y

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

Source

Notes

1.01

no evidence

1.02

http://www.ual.es/personal/edana/alienplants/checklist.pdf

on a checklist of invaive species of Spain and categorized in "1" = with a clear invasive behaviour, although by the moment it is only found in largely disturbed systems. We advise to monitor its further behaviour ‘Invasiveness’ follows the recent proposal by Richardson, D., Pysek, P., Rejmánek, M., Barbour, M.G., Panetta, F.D. & West, C.J. 2000. Naturalization and invasion of alien plants: concepts and definitions. Diversity and Distributions 6: 93–107. [invasive means naturalized and/or spreading and does not imply ecological harm or weediness according to definition used]

1.03

no evidence

2.01

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?bluestem+yucca (16 December 2003)

Distributional range:
Native:
SOUTHERN AMERICA Mesoamerica: Belize; Costa Rica; Guatemala; Honduras; Mexico - Chiapas; Panama
Other: also cultivated

2.02

2.03

(1)Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7. (2)http://ecocrop.fao.org/

(1)Hardiness Range 9B to 11 (2) tropical wet & dry (Aw), tropical wet (Ar), subtropical humid (Cf), subtropical dry summer (Cs), subtropical dry winter (Cw); t occurs naturally in very dry areas but tolerates heavy rainfall if drainage is good.

2.04

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?bluestem+yucca (16 December 2003)

Distributional range:
Native:
SOUTHERN AMERICA Mesoamerica: Belize; Costa Rica; Guatemala; Honduras; Mexico - Chiapas; Panama
Other: also cultivated

2.05

(1) Labanowski, G. (1998) The yucca eriophyid.[FT: Szpeciel jukkowiec. ]Ochrona Rolin, 1998, Vol.42, No.7, p.7
(2) Sakr, S. S.; El-Khateeb, M. A.; Abd El-Kareim, A. H. (1999) In vitro production of Yucca elephantipes . Bulletin of Faculty of Agriculture, University of Cairo, 1999, Vol.50, No.2, pp.265-282, 28 ref.
(3) Morton, J. F.; Dawling, C. F., Jr. (1991) The spineless yucca deserves more attention as an ornamental and food plant. Proceedings of the Florida State Horticultural Society, 1991, Vol.104, pp.341-345, 42 ref.
(4) Allemand, P.; Berninger, E. (1985) Frost damage to ornamental trees and shrubs of the Mediterranean coast-line. [FT: Les dégâts du froid aux arbres et arbustes d'ornement du littoral méditerranéen.] P.H.M.-Revue Horticole, 1985, No.259, pp.45-48

(1) Poland, (2) Egypt, (3) Florida, USA, (4) France

3.01

http://www.ual.es/personal/edana/alienplants/checklist.pdf

on a checklist of invaive species of Spain and categorized in "1" = with a clear invasive behaviour, although by the moment it is only found in largely disturbed systems. We advise to monitor its further behaviour ‘Invasiveness’ follows the recent proposal by Richardson, D., Pysek, P., Rejmánek, M., Barbour, M.G., Panetta, F.D. & West, C.J. 2000. Naturalization and invasion of alien plants: concepts and definitions. Diversity and Distributions 6: 93–107. [invasive means naturalized and/or spreading and does not imply ecological harm or weediness according to definition used]

3.02

http://www.ual.es/personal/edana/alienplants/checklist.pdf

on a checklist of invaive species of Spain and categorized in "1" = with a clear invasive behaviour, although by the moment it is only found in largely disturbed systems. We advise to monitor its further behaviour ‘Invasiveness’ follows the recent proposal by Richardson, D., Pysek, P., Rejmánek, M., Barbour, M.G., Panetta, F.D. & West, C.J. 2000. Naturalization and invasion of alien plants: concepts and definitions. Diversity and Distributions 6: 93–107. [invasive means naturalized and/or spreading and does not imply ecological harm or weediness according to definition used]

3.03

no evidence

3.04

http://www.ual.es/personal/edana/alienplants/checklist.pdf

on a checklist of invaive species of Spain and categorized in "1" = with a clear invasive behaviour, although by the moment it is only found in largely disturbed systems. We advise to monitor its further behaviour. ‘Invasiveness’ follows the recent proposal by Richardson, D., Pysek, P., Rejmánek, M., Barbour, M.G., Panetta, F.D. & West, C.J. 2000. Naturalization and invasion of alien plants: concepts and definitions. Diversity and Distributions 6: 93–107. [invasive means naturalized and/or spreading and does not imply ecological harm or weediness according to definition used; this plant appear to be confined to disturbed areas so, it would be considered a DISTURBANCE weed if it were seen as a problem]

3.05

Sosebee, R. E.; Churchill, F. M.; Green, C. W. (1982) Soil water depletion by yucca. Journal of Range Management, 1982, Vol.35, No.6, pp.774-776, 11 ref.

AB: Soil water at depth 0-60 cm was recorded from April 1971 to Aug. 1975 on newly cleared rangeland in Texas which was infested with or kept free of Yucca glauca, Y. constricta and their hybrids. Herbage yields were recorded in Aug. 1972, 1973 and 1974. Yucca-infested rangeland (2500 or 5000 plants/ha) had a significantly lower water content than yucca-free rangeland. In 1973, grass production was also significantly reduced on infested land when soil water content was high. It was concluded that complete control of yucca is necessary to increase soil water content.  [Yucca glauca, Y. constricta and their hybrids are considered a weed in rangeland which decrease water availability]

4.01

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

Unlike its close relative, Spanish Bayonet, Spineless Yucca can be used in close range of people since it lacks the formidable, terminal spine and has harmless leaves.

4.02

no evidence

4.03

no evidence

4.04

no evidence

4.05

http://ecocrop.fao.org/

leaves used as food and vegetables

4.06

(1) Labanowski, G. (1998) The yucca eriophyid.[FT: Szpeciel jukkowiec. ]Ochrona Rolin, 1998, Vol.42, No.7, p.7
ET: Occurrence of Badnavirus -like particles from Yucca elephantipes .
AU: Rivas, E. B.; Duarte, L. M. L.; Alexandre, M. A. V.; Galleti, S. R.
AA: Seção de Virologia Fitopatalógica e Fisiopatologia, Instituto Biológico, Caixa Postal 7119, 01064-970, São Paulo, SP, Brazil.
SO: Fitopatologia Brasileira, 1994, Vol.19, No.3, pp.479-482, 7 ref.
AB: EM was used to examine leaf tissues of Y. elephantipes , showing yellow and necrotic spots, rings and semi-rings symptoms. Virus-like particles were observed, which measured c . 170-210 nm x 35-40 nm, had rounded ends and were tubular in shape. All attempts to transmit the virus to several hosts failed. Based on these preliminary results, it is suggested that the virus-like particles found in Y. elephantipes were similar to those of Yucca bacilliform virus reported in Italy. This is the first report of Badnavirus -like particles in Yucca in

Brief notes are given on the morphology, harmfulness and control of Cecidophyopsis hendersoni on Yucca elephantipes in Poland, where is was first recorded in 1992, having been introduced from the Netherlands. Mitac [amitraz], Talstar [bifenthrin] and Rufast [acrinathrin] are recommended for its control. [REFERENCE?]

4.07

(1)Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7. (2)http://edis.ifas.ufl.edu/ST675

(1)This plant is considered mostly allergy free and causes little or no allergy problems in most people. (2)Blooms are edible and high in calcium and potassium and can be used in salads. Leaves contain large amounts of ascorbic acid.

4.08

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

Low flammability, Succulent perennial

4.09

(1)Horticopia A-Z.Horticopia, Inc., Purcellville, VA. ISBN 1-887215-07-7. (2)http://ecocrop.fao.org/ (3)http://www.chelseagardencenter.com/tropicalplants/yucca.html (4)http://www.mrec.ifas.ufl.edu/Foliage/folnotes/yucca.htm

(1)Exposure Partial shade or partial sun to full sun (2)tolerates light shade (3) An excellent choice for low light (4)better color and appearance are produced if plants are maintained in 50-60% shade (6,000-7,000 ft-c)

4.1

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

Soil Condition: Loamy, sandy, clay, acidic, neutral, alkaline, tolerates salt, drought tolerant

4.11

http://hort.ifas.ufl.edu/trees/YUCELEA.pdf

Spineless Yucca is the tallest of the Yuccas, reaching 30 feet in height with a 15-foot spread, its single, thick, rough trunk topped with straplike, four-foot-long leaves (

4.12

http://hort.ifas.ufl.edu/trees/YUCELEA.pdf

Spineless Yucca is the tallest of the Yuccas, reaching 30 feet in height with a 15-foot spread, its single, thick, rough trunk topped with straplike, four-foot-long leaves (

5.01

terrestrial

5.02

Agavaceae

5.03

no evidence

5.04

http://hort.ifas.ufl.edu/trees/YUCELEA.pdf

Spineless Yucca is the tallest of the Yuccas, reaching 30 feet in height with a 15-foot spread, its single, thick, rough trunk topped with straplike, four-foot-long leaves (

6.01

no evidence

6.02

(1)http://hort.ifas.ufl.edu/trees/YUCELEA.pdf (2)http://www.bioone.org/bioone/?request=get-document&issn=0013-8746&volume=093&issue=03&page=0432

(1)Propagation is by seed or by cuttings of any size. (2)The only species that seems to produce seeds outside the new world is Yucca aloifolia, which make viable seeds in the old world. I

6.03

http://64.177.111.31/Y_names_UK.htm

Yucca elephantipes X Yucca filifera [don't know if it is natural]

6.04

http://64.177.111.31/Yucca_UK.htm

In the old world and other places Yuccas has been introduced and has naturalized, but only vegetatively, while Yuccas need a specific moth to be pollinated. The only species that seems to produce seeds outside the new world is Yucca aloifolia, which make viable seeds in the old world. I have reports of fruits from: Spain (on several of the Spanish isle's), Italy, Switzerland (Bodensee) and Hungary (Budapest botanical garden).

6.05

http://www.bioone.org/bioone/?request=get-document&issn=0013-8746&volume=093&issue=03&page=0432

(1)Parategeticula elephantipella Pellmyr & Balcázar-Lara, New Species
Known host species Yucca elephantipes. Oviposition site not known, but similarity in ovipositor shape with P. pollenifera suggests that eggs are laid in a groove on the pedicel or peduncle. Examination and dissection of 15 fruits from the type locality at different stages of fruit maturation showed that the first-instar larva bores into the young fruit, with entry holes apparent on surface of young fruit. Feeding on developing seeds, the larva causes partial fusion of 2–5 seeds (mean 3.7 ± 1.0; n = 18) that are excavated. In contrast to P. pollenifera (Powell 1984 , Figs. 39–42), no tissue change in adjacent areas was found. Powell (1984) reported that some larval galleries in older fruits more resembled those of P. pollenifera; I have not been able to examine those remains. Up to 18 larvae were found inside a single fruit during dissection, resulting in most seeds being destroyed. The mature, dull red larva exits the fruit as it ripens an

6.06

http://hort.ifas.ufl.edu/trees/YUCELEA.pdf

Suckers at the base of the plant root quite easily

6.07

(1)http://ecocrop.fao.org/ (2)http://www.abc.net.au/gardening/stories/s115396.htm

(1)First harvest can be taken 2-3 years after cuttings. [harvest of leaves must occur before flowering, so must be at least 4 years before fruit maturation] (2)when three to four years old it bears dense masses of white or cream flowers once or twice a year.

7.01

http://www.mrec.ifas.ufl.edu/Foliage/folnotes/yucca.htm

Yucca are easily propagated from fresh healthy cane. Almost any size cane will produce good plants [could be accidentaly spread by garden waste]

7.02

an ornamental

7.03

no evidence

7.04

http://hort.ifas.ufl.edu/trees/YUCELEA.pdf

Fruit covering: fleshy

7.05

does not grow near flowing water

7.06

(1)http://hort.ifas.ufl.edu/trees/YUCELEA.pdf (2)http://www.faculty.ucr.edu/~legneref/ethnic/ethnic6.htm

(1) Fruit shape: oval
Fruit length: .5 to 1 inch
Fruit covering: fleshy
Fruit color: brown
Fruit characteristics: does not attract wildlife (2)Orinoco Apple -- fruit is eaten {fruit is clearly edible by people, named as an apple so could be bird dispersed but possible mammals]

7.07

(1)http://hort.ifas.ufl.edu/trees/YUCELEA.pdf (2)http://www.faculty.ucr.edu/~legneref/ethnic/ethnic6.htm

(1) Fruit shape: oval
Fruit length: .5 to 1 inch
Fruit covering: fleshy
Fruit color: brown
Fruit characteristics: does not attract wildlife (2)Orinoco Apple -- fruit is eaten {fruit is clearly edible by people, named as an apple so could be bird dispersed but possible mammals]

7.08

(1)http://hort.ifas.ufl.edu/trees/YUCELEA.pdf (2)http://www.faculty.ucr.edu/~legneref/ethnic/ethnic6.htm

(1) Fruit shape: oval
Fruit length: .5 to 1 inch
Fruit covering: fleshy
Fruit color: brown
Fruit characteristics: does not attract wildlife (2)Orinoco Apple -- fruit is eaten {fruit is clearly edible by people, named as an apple so could be bird dispersed but possible mammals]

8.01

http://hort.ifas.ufl.edu/trees/YUCELEA.pdf

Fruit length: .5 to 1 inch [don't know how many seeds per fruit; requires moth pollinator]

8.02

http://www.bennyskaktus.dk/propagat_UK.htm#yucca_seed

The seeds are long lived and can be stored for at least 4-5 years at room temperature. [genus Yucca]

8.03

no evidence

8.04

http://hort.ifas.ufl.edu/trees/YUCELEA.pdf

Sprouts often grow from the base of the trunk forming a multitrunked tree. Suckers at the base of the plant root quite easily.[ability to resprout and sucker]

8.05

no evidence