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

Dasylirion quadrangulatum Lem. Synonym: Dasylirion longissimum; grass palm, Mexican grass tree, toothless sotol, toothless desert spoon

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

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

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

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

n

4.01

Produces spines, thorns or burrs

y=1, n=0

y

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

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

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

3

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

n

7.05

Propagules water dispersed

y=1, n=-1

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

n

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

n

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

y=-1, n=1

Total score:

-4

Source

Notes

1.01

no evidence

1.02

no evidence

1.03

no evidence

2.01

Origin: Eastern Mexico (Coahuila, Tamaulipas, San Luis Potosi)

http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html

2.02

2.03

(1)USDA: 8b-11; Frost Tolerance: Hardy to 20°F (-6°C); Heat Tolerance: Excellent (2)dry conditions [xerophyte] (3)This species occurs mainly along stream beds and is less frequently found along the drier rocky hills

(1)http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html (2)http://www.plantes-ornementales.com/english/d-longissimum.html (3)http://tucsoncactus.org/cgi-bin/db/dbman/db.cgi?db=default&uid=default&view_records=1&ID=*&nh=7

2.04

Origin: Eastern Mexico (Coahuila, Tamaulipas, San Luis Potosi)

http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html

2.05

(1) California, Oklahoma (2) UK

(1) http://davesgarden.com/pf/go/56975/index.html (2) http://www.mulu.co.uk/plant_info.php?id=221

3.01

no evidence

3.02

no evidence

3.03

no evidence

3.04

non-invasive species that stays where you put it

http://www.cacti.com/serragardens/html/otherstocks.html

3.05

no evidence

4.01

spiny leaf margins are sharp

http://www.asiangardens.nl/dasylirion/dasylirionquadrangulatum.htm

4.02

no evidence

4.03

no evidence

4.04

no evidence

4.05

no evidence

4.06

no evidence

4.07

no evidence

4.08

fire proof.

http://www.cacti.com/serragardens/html/otherstocks.html

4.09

(1)Sun Exposure: Full sun to shade (2)Full sun

(1)http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html (2)http://www.plantes-ornementales.com/english/d-longissimum.html

4.1

Soil : All , but fast-draining

http://www.plantes-ornementales.com/english/d-longissimum.html

4.11

Evergreen trunk forming shrub, slowly up to 12 feet tall (3.6 m), 8 feet in diameter (2.4 m)

http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html

4.12

Evergreen trunk forming shrub, slowly up to 12 feet tall

http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html

5.01

Watering Needs: Little water when established, needs good drainage

http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html

5.02

Evergreen trunk forming shrub, slowly up to 12 feet tall (3.6 m), 8 feet in diameter (2.4 m); Agavaceae

http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html

5.03

no evidence

5.04

Evergreen trunk forming shrub, slowly up to 12 feet tall (3.6 m), 8 feet in diameter (2.4 m); Agavaceae

http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html

6.01

no evidence

6.02

Propagation: Seeds

http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html

6.03

no evidence

6.04

no evidence

6.05

[base on floral morphology it is visited by bees and/or moths; heavy pollen presentation]

http://www.trevenacross.co.uk/~offers/images/dasylironflower.jpg

6.06

Propagation: Seeds

http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html

6.07

The plant will flower in three to five years from seed in late spring or early summer.

http://www.greenbeam.com/features/plant090699.stm

7.01

no evidence

7.02

an ornamental

http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html

7.03

no evidence

7.04

Fruits capsular, 1-locular, dry, indehiscent, 3-winged. Seed 1, golden brown, 3-angled [indehisent fruit, seed not wind-dispersed]

http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=109344

7.05

This species occurs mainly along stream beds and is less frequently found along the drier rocky hills [potentially dispersed in flash floods]

http://tucsoncactus.org/cgi-bin/db/dbman/db.cgi?db=default&uid=default&view_records=1&ID=*&nh=7

7.06

(1)Fruits capsular, 1-locular, dry, indehiscent, 3-winged. Seed 1, golden brown, 3-angled [fruit a capsule] (2)Fruit red when mature [don't know if fleshy]

(1)http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=109344 (2)http://mobot.mobot.org/cgi-bin/search_vast?ssdp=01971167

7.07

[seeds possibly cached by desert rodents]

7.08

(1)Fruits capsular, 1-locular, dry, indehiscent, 3-winged. Seed 1, golden brown, 3-angled [fruit a capsule] (2)Fruit red when mature [don't know if fleshy]

(1)http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=109344 (2)http://mobot.mobot.org/cgi-bin/search_vast?ssdp=01971167

8.01

(1)In summer, the plant generates hundreds of brownish-yellow flowers on a long spike that can reach 15 feet (4.5 m). (2) Flower spikes can reach 10-12 feet high and look like giant asparagus stalks when they are forming. Each crown blooms only once, but new crowns form continually so plants should flower every year once they mature.(3) Fruits capsular, 1-locular, dry, indehiscent, 3-winged. Seed 1, golden brown, 3-angled [only one seed per fruit]

(1) http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html (2) http://www.greenbeam.com/features/plant090699.stm (3) http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=109344

8.02

(1)Propagation: Easy from seed. Sow in a warm greenhouse and germination occurs in about two weeks. Salable 1-quart plants can be produced in one year. (2)very easy to germinate and need up to 1 month to sprout

(1)http://www.greenbeam.com/features/plant090699.stm (2)http://www.rarepalmseeds.com/pix/DasQua.shtml

8.03

no evidence

8.04

(1)Evergreen trunk forming shrub, slowly up to 12 feet tall (3.6 m), 8 feet in diameter (2.4 m) [probably not, slow growing trunck forming plant] (2)No pruning should be carried out on this shrub

(1)http://www.desert-tropicals.com/Plants/Agavaceae/Dasylirion_longissimum.html (2)http://www.practical-garden-shrubs.com/white/Dasylirion-Longissimum-White-flowers-.html

8.05

no evidence