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

Phormium tenax; New Zealand flax

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

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

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

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

y

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

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

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

y

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

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

y

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

6

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

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

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:

8

Source

Notes

1.01

no evidence

1.02

The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf>

"P. tenax is currently one of the top 10 priority weed species of The Nature Conservancy of Hawaii's (TNCH) Kamakou Preserve, Molokai. P.tenax is established in the Montane Ohia-Uluhe rainforest of Kamakou Preserve at approximately 3750 ft. The main population, which is located just above Puu Kolekole, thrives in a very wet flat area with poor drainage. It grows in relatively intact native forest and disturbed grassland. Plants have been observed to root on the ground, in hapuu trunks, open pig disturbed grassland, and along steep ridges."

1.03

Fuentealba, J.; Barriga, P.; Urbina, P. (1975) Preliminary observations on the performance of varieties of New Zealand flax (Phormium tenax F.). [FT: Observaciones preliminares sobre el comportamiento de cultivares de formio (Phormium tenax F.).] Agro Sur, 1975, Vol.3, No.2, pp.131-134, 5 ref.

AB: A comparison of three varieties showed that Nueva Zelandia [New Zealand] had the most leaves per plant and that Nacional [National] was significantly shorter than the other two. Nueva Zelandia and Dronceado [Bronze] had a higher proportion of leaves over 50 cm wide than Nacional.
[Several varieties are known, but no indication of specific race being weedy]

2.01

USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network - (GRIN). [Online Database] National Germplasm Resources Laboratory, Beltsville, Maryland. Available: http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?28069 (12 February 2003)

Distributional range:
Native: New Zealand

2.02

2.03

(1)The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf> (2)http://florawww.eeb.uconn.edu/acc_num/198700270.html (3)http://www.hear.org/pier/phtenp.htm

(1)P. tenax originates from New Zealand where it grows in swamps, by streams, and on hillsides (2)Lowland swamps and intermittantly flooded land, Plants tolerate occasional flooding with saline water (3)principally in gullies in mesic areas below 300 m

2.04

(1)Wagner et al. Mannual of the Flowering plants of Hawaii. (2)Vitek, E.; Dobes, C. (2000) Phormium tenax (Phormiaceae) , locally naturalised on the Cantabrian Coast (Spain). Anales del Jardín Botánico de Madrid, 2000, Vol.58, No.2, p.363, 24 ref.

(1)Naturalized in Hawaii (2)Phormium tenax , New Zealand flax, is locally naturalized on the Cantabrian coast of Spain. The authors highlight the potential invasion of P. tenax along the coast. [Mediterranean]

2.05

(1) Cocozza Talia, M. A.; Lucia, B. de (1999) Utilization of three ornamental monocotyledons for vertical green spaces in southern Italy. Acta Horticulturae, 1999, No.486, pp.261-264, 1 ref.
(2) Vitek, E.; Dobes, C. (2000) Phormium tenax (Phormiaceae) , locally naturalised on the Cantabrian Coast (Spain). Anales del Jardín Botánico de Madrid, 2000, Vol.58, No.2, p.363, 24 ref.
(3) Bartlett, P. W. (1981) Trionymus diminutus (Leonardi) (Homoptera: Pseudococcidae) infesting New Zealand flax in England. Plant Pathology, 1981, Vol.30, No.1, pp.56-58, 3 ref.

(1) Italy, (2) Spain, (3) England

3.01

Vitek, E.; Dobes, C. (2000) Phormium tenax (Phormiaceae) , locally naturalised on the Cantabrian Coast (Spain). Anales del Jardín Botánico de Madrid, 2000, Vol.58, No.2, p.363, 24 ref.

AB: Phormium tenax , New Zealand flax, is locally naturalized on the Cantabrian coast of Spain. The authors highlight the potential invasion of P. tenax along the coast.

3.02

no evidence

3.03

no evidence

3.04

(1)The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf> (2)www.bbg.org/gar2/topics/botany/con_worst.html (3)http://www.brim.vic.gov.au/Environment/landscape/PracticeNote5.pdf (3)http://www.botany.hawaii.edu/faculty/cw_smith/pho_ten.htm

(1) "P. tenax is currently one of the top 10 priority weed species of The Nature Conservancy of Hawaii's (TNCH) Kamakou Preserve, Molokai. P.tenax is established in the Montane Ohia-Uluhe rainforest of Kamakou Preserve at approximately 3750 ft. The main population, which is located just above Puu Kolekole, thrives in a very wet flat area with poor drainage. It grows in relatively intact native forest and disturbed grassland. Plants have been observed to root on the ground, in hapuu trunks, open pig disturbed grassland, and along steep ridges." (2)Only recognized as invasive in Hawaii, not other states. (3)Not recognized as invasive in Australia (4)This rosette-like lily forms dense thickets from which other species are excluded. Moloka'i, and the northern Hamakua coastline, Hawai'i.

3.05

no evidence

4.01

The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf>

no description of these traits

4.02

no evidence

4.03

no evidence

4.04

(1)Kelton, S. D.; Skipworth, J. P. (1987) Food of sambar deer (Cervus unicolor ) in a Manawatu (New Zealand) flax swamp. New Zealand Journal of Ecology, 1987, Vol.10, pp.149-152, 19 ref. (2)http://www.gardenbed.com/p/2610.cfm

(1)The diet of C. unicolor in a Phormium tenax wetland in New Zealand was studied over 1 year. Of 12 plant species eaten, 5 (P. tenax, Glyceria fluitans, Festuca arundinacea, Phalaris arundinacea and Stellaria media ) comprised >90% of the total in all samples and were selected for study. Over the 12-month period, 79% of the diet consisted of only P. tenax (32%), G. fluitans (29%) and F. arundinacea (18%), representing a seasonal loss of high quality forage species and a resulting shift in diet to more abundant but lower quality vegetation. (2)Members of this genus are rarely if ever troubled by browsing deer or rabbits[

4.05

Kelton, S. D.; Skipworth, J. P. (1987) Food of sambar deer (Cervus unicolor ) in a Manawatu (New Zealand) flax swamp. New Zealand Journal of Ecology, 1987, Vol.10, pp.149-152, 19 ref.

AB: The diet of C. unicolor in a Phormium tenax wetland in New Zealand was studied over 1 year. Of 12 plant species eaten, 5 (P. tenax, Glyceria fluitans, Festuca arundinacea, Phalaris arundinacea and Stellaria media ) comprised >90% of the total in all samples and were selected for study. Over the 12-month period, 79% of the diet consisted of only P. tenax (32%), G. fluitans (29%) and F. arundinacea (18%), representing a seasonal loss of high quality forage species and a resulting shift in diet to more abundant but lower quality vegetation.

4.06

Andersen, M. T.; Longmore, J.; Liefting, L. W.; Wood, G. A.; Sutherland, P. W.; Beck, D. L.; Forster, R. L. S. (1998) Phormium yellow leaf phytoplasma is associated with strawberry lethal yellows disease in New Zealand. Plant Disease, 1998, Vol.82, No.6, pp.606-609, 37 ref.

AB: A yellows disease of strawberry (cv. Pajaro) plants was identified in propagation beds in New Zealand. Affected plants were flatter to the ground, showed purpling of older leaves, reduced leaf size, yellowing of younger leaves, and sometimes plant death. A phytoplasma was observed in the phloem of affected plants using transmission electron microscopy. The 16S rRNA gene of the phytoplasma was amplified by polymerase chain reaction from symptomatic plants and from 1 asymptomatic plant, but not from 36 other asymptomatic plants. Nucleotide sequence analysis of the 16S rRNA gene showed that the phytoplasma is closely related or identical to the phytoplasma associated with the yellow leaf disease of New Zealand flax (Phormium tenax ). [not shown to be the same]

4.07

no evidence

4.08

no evidence

4.09

(1)Horticopia, Inc. (2002) Horticopia Plant Information. Available at<http://www.hortpix.com/index.html> (2)http://www.gardenbed.com/p/2610.cfm

(1)prefers partial shade or partial sun to full sun (2)Tolerates light shade but prefers full sun

4.1

(1) Sykes, M. T.; Wilson, J. B. (1990) An experimental investigation into the response of New Zealand sand dune species to different depths of burial by sand. Acta Botanica Neerlandica, 1990, Vol.39, No.2, pp.171-181, 26 ref.
(2) The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf> (3)http://www.gardenbed.com/p/2610.cfm

(1) sand dune; (2) The main population, which is located just above Puu Kolekole, thrives in a very wet flat area with poor drainage. [from totally sand to very compact soil] (3)Prefers a rich loamy soil but is not too fussy, succeeding in peaty soils and in boggy moorland

4.11

The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf>

Leaves rise from the ground in an erect two-rowed cluster like a fan.

4.12

The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf>

"New clones sprout along a rhizome and quickly expand into a dense clump that crowds out other vegetation."

5.01

(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf>

"P. tenax originates from New Zealand where it grows in swamps, by streams, and on hillsides." [life cycle not aquatic]

5.02

Agavaceae

5.03

no evidence

5.04

The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf>

"New clones sprout along a rhizome and quickly expand into a dense clump that crowds out other vegetation."

6.01

no evidence

6.02

MacKay, A. C.; McGill, C. R.; Fountain, D. W.; Southward, R. C. (2002) Seed dormancy and germination of a panel of New Zealand plants suitable for re-vegetation. New Zealand Journal of Botany, 2002, Vol.40, No.3, pp.373-382, 36 ref.

AB: "A low percentage of Phormium tenax seeds germinated in both the light and dark in the first month with no further germination, but after 8 weeks or more of low temperature stratification there was almost complete germination."

6.03

http://www.gardenbed.com/p/2610.cfm

This species hybridizes readily with P. colensoi and there are many named forms that may be hybrids with that species [both native to New Zealand, so natural hybrids are presumed]

6.04

Craig, J. L. (1989) A differential response to self pollination: seed size in Phormium. New Zealand Journal of Botany, 1989, Vol.27, No.4, pp.583-586, 26 ref.

AB: "Self-pollination from the same inflorescence produced many small seeds and the fewest large seeds. These had the least endosperm. Self-pollination between inflorescences of the same plant produced more large seeds with intermediate amounts of endosperm. Naturally outcrossed flowers produced mainly large seeds and these had the most endosperm. "

6.05

(1) Murphy, C.; Robertson, A. (2000) Preliminary study of the effects of honey bees (Apis mellifera ) in Tongariro National Park. Science for Conservation, 2000, No.139, 18 pp., 19 ref.
(2) Craig, J. L. (1989) Seed set in Phormium : interactive pollinator behaviour, pollen carryover and pollen source. Oecologia, 1989, Vol.81, No.1, pp.1-5, 32 ref.

(1) AB: "Phormium tenax is thought to be predominately bird pollinated, but the floral resources are also utilized by a variety of native and introduced insect species including honey bees. Fruit and seed set was significantly higher at sites with bird visitation. It is also suggested that flax has a flexible pollination system that enables it to maintain a range of fruit and seed set levels under different pollinator regimes."
(2) AB: "Fruit set was low and, in particular situations, could result from insufficient pollinator visitation. Observations of pollinator (Meliphagidae) movements showed that birds, mainly Prosthemodera novaeseelandiae, preferentially visited male phase flowers and predominantly moved pollen within inflorescences of the same plant. More dominant resident birds moved more between plants than subordinate non-resident birds. Combination of results of fluorescent dye carryover with known bird movements allowed predictions of fruit set and seed size that closely approximated observed le

6.06

The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf>

"New clones sprout along a rhizome and quickly expand into a dense clump that crowds out other vegetation. Resprouts from the base of a mature plant occurs even after the plant has been uprooted."

6.07

Beckett, K. (1992) The New Zealand flaxes. Garden (London), 1992, Vol.117, No.12, pp.587-589. p.588

"In my experiences, plants raised from seeds have never flowered at less than 6 or 7 years."

7.01

no evidence

7.02

The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf>

"The silky cream-colored fiber was used to produce rope and twine. The Maoris used the fiber to make clothing, mats, baskets, and cord. The root was used medicinally. P. tenax was cultivated in Hawaii prior to 1871 and is currently naturalized at least on Kauai and Molokai."

7.03

no evidence

7.04

The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf>

"The seeds are glossy black, 9-10 mm long, flattened and winged along the upper half."; "Numerous winged seed are dispersed from capsules on a 4-5 meter tall stalk."

7.05

occurs in semi-aquatic environments

7.06

no evidence

7.07

no evidence

7.08

no evidence

8.01

The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf>

"We estimate that over 10,000 seeds could be produced from one inflorescence stalk. (Note that this number is an extrapolation from a single collection at Puu Kolekole.)"

8.02

(1)MacKay, A. C.; McGill, C. R.; Fountain, D. W.; Southward, R. C. (2002) Seed dormancy and germination of a panel of New Zealand plants suitable for re-vegetation. New Zealand Journal of Botany, 2002, Vol.40, No.3, pp.373-382, 36 ref. (2)http://www.gardenbed.com/p/2610.cfm

(1)"A low percentage of Phormium tenax seeds germinated in both the light and dark in the first month with no further germination, but after 8 weeks or more of low temperature stratification there was almost complete germination." (2)Germination is sometimes poor but should take place in 1 - 6 months at 15°c. The seedlings are very variable. The seed remains viable for about 12 months in normal storage

8.03

The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf>

"For large clumps, foliage is cut off down to its base and sprayed with 10-50 % Round-up. A second treatment is necessary to completely kill regrowth."

8.04

The Nature Conservancy of Hawaii, Molokai Office
(P.O. Box 220, Kualapuu, HI 96757; phone: 808-553-5236 / 524-0779 (Oahu direct line), FAX: 808-5539870). Available at: <http://www.hear.org/AlienSpeciesInHawaii/species/phormium_tenax/photen_tnc_molokai_report.pdf>

"Resprouts from the base of a mature plant occurs even after the plant has been uprooted."

8.05

no evidence