Pacific Island Ecosystems at Risk (PIER)


Ilex cassine


RISK ASSESSMENT RESULTS: Evaluate further, score: 3


Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i.
Information on Risk Assessments
Original risk assessment
  Ilex cassine  (Common Names: Dahoon holly) Family: Aquifoliaceae Answer Score
1.01 Is the species highly domesticated? (If answer is 'no' then go to question 2.01) n 0
1.02 Has the species become naturalized where grown?    
1.03 Does the species have weedy races?    
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” 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
2.04 Native or naturalized in regions with tropical or subtropical climates y 1
2.05 Does the species have a history of repeated introductions outside its natural range?  y=-2 n  
3.01 Naturalized beyond native range         y = 1*multiplier (see Append 2), n= question 2.05 n 0
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
3.04 Environmental weed                                                     y = 2*multiplier (see Append 2) n 0
3.05 Congeneric weed                                                          y = 1*multiplier (see Append 2) y 1
4.01 Produces spines, thorns or burrs n 0
4.02 Allelopathic n 0
4.03 Parasitic n 0
4.04 Unpalatable to grazing animals n -1
4.05 Toxic to animals n 0
4.06 Host for recognized pests and pathogens n 0
4.07 Causes allergies or is otherwise toxic to humans    
4.08 Creates a fire hazard in natural ecosystems n 0
4.09 Is a shade tolerant plant at some stage of its life cycle y 1
4.1 Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island) y 1
4.11 Climbing or smothering growth habit n 0
4.12 Forms dense thickets n 0
5.01 Aquatic n 0
5.02 Grass n 0
5.03 Nitrogen fixing woody plant n 0
5.04 Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers) n 0
6.01 Evidence of substantial reproductive failure in native habitat n 0
6.02 Produces viable seed. y 1
6.03 Hybridizes naturally    
6.04 Self-compatible or apomictic n -1
6.05 Requires specialist pollinators n 0
6.06 Reproduction by vegetative fragmentation n -1
6.07 Minimum generative time (years)                 1 year = 1, 2 or 3 years = 0, 4+ years = -1 4 -1
7.01 Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas) y 1
7.02 Propagules dispersed intentionally by people y 1
7.03 Propagules likely to disperse as a produce contaminant n -1
7.04 Propagules adapted to wind dispersal n -1
7.05 Propagules water dispersed    
7.06 Propagules bird dispersed y 1
7.07 Propagules dispersed by other animals (externally) n -1
7.08 Propagules survive passage through the gut y 1
8.01 Prolific seed production (>1000/m2) n -1
8.02 Evidence that a persistent propagule bank is formed (>1 yr)    
8.03 Well controlled by herbicides    
8.04 Tolerates, or benefits from, mutilation, cultivation, or fire y 1
8.05 Effective natural enemies present locally (e.g. introduced biocontrol agents)    
  Total score:   3
  Second screening   Evauate further

Supporting data:

  Notes Reference
1.01 No evidence  
1.02    
1.03    
2.01 (1)"Ilex cassine is native to the eastern United States from Virginia to Florida to Louisiana. "  (2)"South-eastern N. America - Virginia to Florida, west to Texas."  (3)"Native to the Atlantic coastal plain of the southeastern and eastern U.S. and reported from Cuba and teh Bahama Islands, dahoon typically grows in low swamy ground ... " (1)http://www.floridata.com/ref/I/ilx_cas.cfm  (2)http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine   (3)Staples, W George and Derral H Herbst. 2005. A Tropical Garden Flora. Bishop Museum Press. Honolulu. Hawaii. Page 130.
2.02    
2.03 (1)"Hardiness: USDA Zones 5-10."  (2)"USDA hardiness zones: 7 through 11" (1)http://www.floridata.com/ref/I/ilx_cas.cfm  (2)http://72.14.253.104/search?q=cache:j-eZ52MPHwgJ:hort.ufl.edu/trees/ILECASA.pdf+%22Ilex+cassine%22&hl=en&gl=us&ct=clnk&cd=2
2.04 (1)"Ilex cassine is native to the eastern United States from Virginia to Florida to Louisiana. "  (2)"South-eastern N. America - Virginia to Florida, west to Texas." (1)http://www.floridata.com/ref/I/ilx_cas.cfm  (2)http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine
2.05 (1)Introduced to Puerto Rico.  (2)Introduced to Hawaii   [Other than Hawaii no evidence of further introductions - Puerto Rico is included as part of its natural range by some authors e.g. in Little, E. L. and Wadsworth, F. H. Common Trees of Puerto Rico and the Virgin Island. Volumes  2. U.S. Department of Agriculture. U.S.Governmet Printing Office. Washington D.C. Page 442]. (1)http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=ILCA  (2)http://ravenel.si.edu/botany/pacificislandbiodiversity
hawaiianflora/result.cfm?genus=Ilex&species=cassine&rank1=&epithet1=  
3.01 According to ref(1) - Ilex cassine is naturalized in Hawaii but according to (2)"Ilex cassine L. has been planted along the highway from Hilo to Volcano on Hawaii and in Honolulu, Oahu, but it does not appear to have become naturalized." [Ref (1) is more recent information compared to (2)]. (1)http://ravenel.si.edu/botany/pacificislandbiodiversity/
hawaiianflora/result.cfm?genus=Ilex&species=cassine&rank1=&epithet1=  (2)Wagner, W. L. Herbst, D. L. and Sohmer, S. H. 1999. Manual of Flowering Plants of Hawaii. University of Hawaii Press. Honolulu. Page 222.
3.02 No evidence  
3.03 No evidence  
3.04 No evidence  
3.05 Ilex aquifolium is reported to be invasive by the California Pest Plant council. http://plants.usda.gov/java/profile?symbol=ILAQ80
4.01 No thorns http://72.14.253.104/search?q=cache:j-eZ52MPHwgJ:hort.ufl.edu/trees/ILECASA.pdf+%22Ilex+cassine%22&hl=en&gl=us&ct=clnk&cd=2
4.02 Not allelopathic http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=ILCA
4.03 No evidence  
4.04 Low palatability to grazing and browsing animals. http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=ILCA
4.05 No evidence  
4.06 Probably not - "No pests or diseases are of major concern. A twiggall sometimes forms in response to a fungusinfection. Mites can infest foliage on trees planted ondry sites." "Pest resistance: long-term health usually notaffected by pests." http://72.14.253.104/search?q=cache:j-eZ52MPHwgJ:hort.ufl.edu/trees/ILECASA.pdf+%22Ilex+cassine%22&hl=en&gl=us&ct=clnk&cd=2  (2)
4.07 (1)"Although no reports of toxicity have been seen for this species, at least some members of this genus are slightly toxic so some caution is advised." "The leaves are hypnotic and laxative. A strong decoction of the plant was used by some native North American Indian tribes to induce vomiting. This was seen partly as a physical and partly a spiritual cleansing.  (2)"Although no specific reports of toxicity have been seen for this species, the fruits of at least some members of this genus contain saponins and are slightly toxic. They can cause vomiting, diarrhoea and stupor if eaten in quantity."   (3)Slight toxicity. [Dont know - no evidence of any case of poisoning with Ilex cassine]. (1)http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine  (2)http://www.pfaf.org/database/plants.php?Ilex+cassine  (3)http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=ILCA
4.08 Probably not - An evergreen tree with thick leaves  - (1)"It is often found in swamps and other wet locations where it achieves its greatest size. In warm winter areas the dahoon is evergreen but tends to shed its foliage in colder climates."  (2)"Habitat- Cold swamps and on their borders in rich moist soils. Occasionally also found on high sandy banks of pine barren streams." (1)http://www.floridata.com/ref/I/ilx_cas.cfm  (2)http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine
4.09 (1)"Light: Dahoon is adaptable to most conditions from full sun to deep shade."  (2)"Growing well in full sun to partial shade" (3)Site Requirements: Sun to partial shade  (4)" It can grow in semi-shade (light woodland) or no shade."  (5)Shade tolerant. (1)http://www.floridata.com/ref/I/ilx_cas.cfm  (2)http://72.14.253.104/search?q=cache:j-eZ52MPHwgJ:hort.ufl.edu/trees/ILECASA.pdf+%22Ilex+cassine%22&hl=en&gl=us&ct=clnk&cd=2   (3)http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/trees-new/ilex_cassine.html                (4)http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine   (5)http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=ILCA
4.1 (1)"Likes light sandy soil; native of swamps and boggy areas…"  (2)"Soil tolerances: clay; loam; sand; slightly alkaline;acidic; extended flooding; well-drained"  (3)"range of soil types"range of soil types    (4)"The plant prefers light (sandy), medium (loamy) and heavy (clay) soils. The plant prefers acid, neutral and basic (alkaline) soils."  (5)"Tolerates most soils that are not water-logged"  (6)pH range 3.5 to 6.5 (1)http://www.floridata.com/ref/I/ilx_cas.cfm                                                                                                        (2)http://72.14.253.104/search?q=cache:j-eZ52MPHwgJ:hort.ufl.edu/trees/ILECASA.pdf+%22Ilex+cassine%22&hl=en&gl=us&ct=clnk&cd=2 (3)http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/trees-new/ilex_cassine.html      (4)http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine   (5)http://www.pfaf.org/database/plants.php?Ilex+cassine  (6)http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=ILCA
4.11 No evidence  
4.12 No evidence  
5.01 "Dahoon holly is a small tree that has a narrow growth habit of upward pointing branches that grows to a height of up to 30 ft (9.1 m)." http://www.floridata.com/ref/I/ilx_cas.cfm
5.02    
5.03 No evidence http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=ILCA
5.04    
6.01 Reported to be flowering and fruiting in Florida. http://www.floridata.com/ref/I/ilx_cas.cfm
6.02  (1)"Propagate by seeds and cuttings."  (2)"Propagation is by seeds, which germinate in oneyear, or by cuttings."  (3)"It can take 18 months to germinate. Stored seed generally requires two winters and a summer before it will germinate and should be sown as soon as possible in a cold frame. Scarification, followed by a warm stratification and then a cold stratification may speed up the germination time." (1)http://www.floridata.com/ref/I/ilx_cas.cfm  (2)http://72.14.253.104/search?q=cache:j-eZ52MPHwgJ:hort.ufl.edu/trees/ILECASA.pdf+%22Ilex+cassine%22&hl=en&gl=us&ct=clnk&cd=2    (3)http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine
6.03 (1)"Abstract: Megastigmus floridanus Milliron was discovered to be phytophagous in seeds of Ilex opaca and one of its hybrids with Ilex cassine. This is the first report of a Megastigmus associated with Aquifoliaceae. …"  (2)"Abstract: The diverse relationships of the main differential leaf and nodal anatomical characters of a number of artificial Ilex hybrids [I. aguifolium .times. cornuta, I. aguifolium .times. decidua, I. aguifolium .times. attenuata, I. aguifolium .times. opaca, I. opaca .times. decidua, I. opaca .times. cassine, I. opaca .times. attenuata and I. cassine .times. altaclarensis] and their parents are compared. The marginal sclerenchyma strands character is not transferred to hybrids when differential. The lignification of the unspecialized abaxial epidermal cells is dominantly inherited, except in 1 hybrid. The development of a distinctive adaxial hypodermis is usually suppressed in hybrids when one of its parents is lacking in this character. New characters are reported for hybrids of I. aquifolium .times. opaca, where the vasculation of petiole and midrib and the presence of periclinal subdivisions in the adaxial epidermis constitute features not known from either parent species. The possible significance of the 4 different ways of expression of parental characters in the hybrid offspring is discussed with reference to: genetic control of anatomical characters; the identification of hybrid material; the evolution of leaf anatomical diversity in Ilex, and the systematic value of leaf anatomical characters."  [Dont know if it forms hybrids under natural conditions]. (1)GRISSELL E E MEGASTIGMUS-FLORIDANUS HYMENOPTERA TORYMIDAE NEWLY DISCOVERED IN ILEX SEED AQUIFOLIACEAE
Proceedings of the Entomological Society of Washington 91 (4) : 604-610 1989    (2)BAAS P INHERITANCE OF FOLIAR AND NODAL ANATOMICAL CHARACTERS IN SOME ILEX HYBRIDS Botanical Journal of the Linnean Society 77 (1) : 41-52 1978
 
6.04 (1)"Possessing male and femaleflowers on separate plants, at least two Dahoon Hollies(male and female) must be planted in the landscape toensure production of the brilliant red berries in fall andwinter."   (2)"The flowers are dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown if seed is required) and are pollinated by Bees. The plant not is self-fertile." (1)http://72.14.253.104/search?q=cache:j-eZ52MPHwgJ:hort.ufl.edu/trees/ILECASA.pdf+%22Ilex+cassine%22&hl=en&gl=us&ct=clnk&cd=2  (2)http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine
6.05 "The flowers are dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown if seed is required) and are pollinated by Bees. The plant not is self-fertile." http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine
6.06 No evidence of spread by vegetative means. xxxx
6.07 (1)"An evergreen tree growing to 10m at a slow rate. "  (2)"The seedlings are rather slow-growing."  (3)"rather slow growth. [A slow growing shrub/small tree, probably takes 4 years or more to reach flowering. (1)http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine  (2)"http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine   (3)http://plantanswers.tamu.edu/publications/beaumont/smtrees.html
7.01 Probably yes -  "The dahoon's bright red berries attract hungry birds and other wildlife throughout the winter. They appear in fall just in time to play starring roles in Christmas wreaths and holiday arrangements." [The seeds could be dispersed unintentionally via dried fruits on the wreaths]. http://www.floridata.com/ref/I/ilx_cas.cfm
7.02 Probably yes - the species has ornamental value. "Within its growing range, the dahoon is becoming increasingly available as more nurseries respond to the ever increasing interest in gardening with native species. " http://www.floridata.com/ref/I/ilx_cas.cfm
7.03 Probably not - no evidence of the species being grown in or around seed crops. Also relatively large seeds.  
7.04 No evidence  
7.05 The species inhabits swamps and wet areas seems likely to disperse via water but example to dispersal by such means.  
7.06 (1)"In the winter, female trees are covered with bright red or yellow berries. "   (2)"birds love to eat the berries and use the trees for nest sites" (1)http://www.floridata.com/ref/I/ilx_cas.cfm  (2)http://www.floridagardener.com/FLNatives/Icassine.htm
7.07 No evidence that the species has any means of attachment.  
7.08 "The red fruit is attractive to birds which eat it and disperse the seeds." Staples, W George and Derral H Herbst. 2005. A Tropical Garden Flora. Bishop Museum Press. Honolulu. Hawaii. Page 130.
8.01 Probably not - relatively large seeds -"fruit in stalked clusters, globose, 0.25-0.3" in diameter, red (or yellow), stones 1-4 ribbed.  
8.02 "It can take 18 months to germinate. Stored seed generally requires two winters and a summer before it will germinate and should be sown as soon as possible in a cold frame. Scarification, followed by a warm stratification and then a cold stratification may speed up the germination time." [No evidence regarding seed longevity under natural conditions]. http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine
8.03 No evidence that the species is being controlled for.  
8.04 (1)"tree wants to grow withseveral trunks but can be trained to grow with a singletrunk"  (2)"Plants are very tolerant of pruning and can be cut right back into old wood if required."  (3)"Coppice potential - yes, Resprout ability - yes" (1)http://72.14.253.104/search?q=cache:j-eZ52MPHwgJ:hort.ufl.edu/trees/ILECASA.pdf+%22Ilex+cassine%22&hl=en&gl=us&ct=clnk&cd=2  (2)http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Ilex+cassine   (3)http://plants.nrcs.usda.gov/cgi_bin/topics.cgi?earl=plant_attribute.cgi&symbol=ILCA
8.05 Don’t know.  

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This page created 27 December 2006