Native to southeastern Australia, P. undulatum was widely introduced in the late 1800s as an ornamental tree, and it has now proven invasive in tropical, sub-tropical and warm temperate areas, especially on i...
Native to southeastern Australia, P. undulatum was widely introduced in the late 1800s as an ornamental tree, and it has now proven invasive in tropical, sub-tropical and warm temperate areas, especially on islands. It produces large numbers of fruits and its seeds are eaten by a wide range of frugivorous birds. It is a great colonizer of open, disturbed habitats, as well as being very shade tolerant. It is very competitive, shading out other vegetation, first invading relatively open forest and forming a dense understorey. It is especially threatening in sensitive island montane forests such as those found in the Azores, but also the Pacific islands, the South African fynbos, and even eucalyptus forests in Australia where it is considered a threat to the survival of native forests. It supports a dense soil seed bank and dense seedling recruitment and it also has a good capacity to resprout after cutting.
Pittosporum undulatum is a well-defined species in the family Pittosporaceae; sub-family Pittosporeae, series Bivalvae, and is probably the most widely cultivated Pittosporum species (Cooper, 1956). There are 150-200 species of Pittosporum native to a broad area from the Canary Islands to Pacific islands via tropical Africa and the Himalayas to Japan, though most are native to Australasia where there are thought to be about 50 species (Goodland and Healey, 1996). P. undulatum hybridises naturally in its Australian native range, occasionally with Pittosporum bicolor in Victoria, and possibly also with Pittosporum revolutum further north (Cooper, 1956). There are other species within the genus that are noted as naturalizing or invasive, or potentially so, including Pittosporum pentandrum and Pittosporum viridiflorum in the Pacific (PIER, 2008), and Pittosporum tobira and Pittosporum tenuifolium in the Caribbean (Kairo et al., 2003). These species may also be possibly invasive elsewhere.
Pittosporum, from Greek, means "pitch-seed", referring to the resinous coating on the seeds. The species name undulatum is derived from the Latin unda, a wave or surge, referring to the characteristic wavy edges of the leaves.
P. undulatum can reach 30 m high, though often to 12 m and with a straight trunk and regular branch arrangement in favourable situations, but in dry exposed locations it is a shrub up to 2-3 m. Large trees may have a broad canopy up to 7 m across. Bark is coarse and grey.
The leaves are about 75 mm long with toothed margins. Small, white, fragrant flowers occur in terminal clusters in spring and early summer and are followed by orange-tan berries 1 cm in diameter in autumn, which persist for several months
Leaves alternate, elliptic-oblong to oblanceolate, acuminate at apex, attenuate at base, entire, 6-16 cm long, glossy green above, paler beneath, membranous, margins undulate or flat, sometimes recurved; main vein sunken or raised adaxially, raised abaxially, secondary nerves about 12 per side, distinct; petioles 7-26 mm long, 1-2 mm wide. Inflorescences terminal, 4-15 flowered, subumbelliform; peduncles and pedicels 1.9-3.1 cm long, accresecent in fruit, tomentose; peduncles subtended by a whorl of leaves and numerous caducous, brown-tomentose, ciliolate bud scales 1 - 2 mm long; sepals frequently connate in a tube which splits into 2 parts, one 1 - 2-lobed, the other 3- to 4- lobed, lanceolate, acuminate 6.5-10.5 mm long 1.2-2.5 mm broad, tomentoluse, falling before the petals; petals, linear-lanceolate, to linear-oblong, obtuse, 11-17 mm long, 3-4 mm broad, coherent at the base, spreading to recurved above, creamy-white; stamens 5-11 mm long, sometimes reduced to sterile rudiments 0.5-1.0 mm long; anthers lanceolate-oblong to sagittiform, 2.5-5.0 mm long, 1.0-1.5 mm broad. Pistils at anthesis slightly shorter or longer than the stamens; ovary 4-6 mm long, 1.8-4.0 mm broad, tomentulose; style 2.0-4.5 mm long; stigma capitate and obscurely 2- to 4-lobed or almost truncate. Capsules sub-globose, 2-valved, 10-14 mm in diameter, yellow to brown, smooth to slightly rugose, glabrous; valves convex in transverse section, less than 1 mm thick, coriaceous, with placenta thickened at the base and bearing 2-3 rows of short stout peg-like funicles from the base to just above the middle; seeds 12-22 (-35), about 3 mm long, orangy red to dark red to black, irregular (from Cooper (1956) in Goodland and Healey, 1996).
Plant Type
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Broadleaved Perennial Seed propagated Tree Woody
P. undulatum is native to the coastal belt and mountains of south-eastern Australia, from south-east Queensland in the north, to the south and east of Victoria, in sub-humid forests seawards of the Great Dividing Range, from the Macpherson Range (24°S) to the southern coast (39°S) extending inland up to 280 km (Cooper, 1956). In other parts of Australia it is introduced and naturalised, such as in Tasmania and South Australia. It has been widely introduced to other parts of the world and is likely to be even more widespread than indicated in the Distribution Table.
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
P. undulatum was noted as a cultivated species by Cooper (1956) in Europe, Asia and South America, and it had already been widely introduced in the late 1800s. Goodland and Healey (1996) include reports of P. undulatum from several countries where it was spreading through forest and scrub in montane areas of the tropics, sub-tropics and warm temperate areas, including Australia, New Zealand, South Africa, Pacific, Indian and Atlantic Ocean islands, as well as Jamaica where the study was concentrated. It was introduced to Hawaii by 1875, and Jamaica in 1883 from seeds from Tamil Nadu, India and St Helena in the Atlantic Ocean, as well as directly from its native Australia (Goodland and Healey, 1996), so it must have already been introduced to India and other countries and islands many years earlier. It had also been introduced to South Africa and some other Pacific islands at least by 1901 (Goodland and Healey, 1996).
More so than most ‘alien’ invasive species, however, P. undulatum is also regarded as an important invasive species in its native Australia. It is regarded as invasive in different habitats within its native range, and also where it has been introduced into neighbouring areas, such as elsewhere in Victoria where it is expanding its range, in Western Australia and Tasmania, also King Island in Bass Strait. The species has been the subject of a control programme in Dandenong Ranges National Park, Victoria (Gillespie, 1991). Natural fires limit the range of P. undulatum, and as the frequency of fires decreased during the 1900s as a result of human interventions, it has been able to spread to areas where previously it would have been killed. It is also spreading outside its pre-European range as a result of widespread planting in gardens in addition to the fire suppression policies in areas close to habitations, and the introduction of the European blackbird, Turdus merula. Around Sydney, New South Wales, for example, the natural habitat has been mostly cleared, but increased moisture and soil nutrients running off from urbanised areas into adjacent bushland makes the edges of this infertile habitat suitable, and it is noted as being invasive in such modified habitats.
Following its initial introduction to the Cinchona Botanic Gardens in the Blue Mountains of Jamaica, it first flowered four years later, though there was no mention of P. undulatum in the area 30 years after introduction. However, another 30-35 years later in the 1940s, there were a number of accounts of its escape and spread in the area around the botanic gardens, “regenerating profusely and dominating the woodland understorey”, “had spread immensely”, and had become “perhaps the commonest tree” in neighbouring secondary forest (Goodland and Healey, 1996). Binggeli and Goodland (1997) observed that there is no evidence for any appreciable time lag in invasion in Jamaica, though the rate of spread accelerated since Hurricane Gilbert in 1988, and more invasion of these forests by P. undulatum seems inevitable since such significant disturbance that aids establishment of P. undulatum is relatively common.
It is recorded from many Atlantic islands, on the Azores, Canaries, Bermuda, St Helena and Tristan da Cunha (Goodland and Healey, 1996). It is widespread on St Helena where it has negative impacts on native vegetation, but also has considerable value as a fodder. P. undulatum was introduced to the Azores in the early 1800s to provide wind breaks for orange groves against Atlantic gales because of the density of its canopy; it is particularly invasive here and is now dominant in the once widespread native Myrica faya forest on Pico island. Plantations were established on other islands, but native trees are not found under P. undulatum or under another plantation tree Cryptomeria japonica, although they are found under Eucalyptus and Acacia.
In the Pacific, P. undulatum was introduced to Lord Howe Island in 1898 as a windbreak tree and has spread slowly into undisturbed forest; to the Norfolk Islands before 1903, where it has naturalised; and to Hawaii before 1875. It is now naturalised on Maui and Kaho’olawe islands and noted as one of the worst 40 invasive weeds in the Hawaii Volcanoes National Park. P. undulatum is also naturalised in New Zealand (Gleadow and Ashton, 1981) but is not mentioned as an environmental weed by Owen (1996). Noting the locations of some populations, some consider that it may have even been introduced accidentally by birds, either from Norfolk Island where it was introduced, or directly from its native Australia.
P. undulatum was widely planted in gardens around Cape Town, South Africa, and was seen spreading into tall scrub and riparian forest in Cape Province, though it was only considered a minor weed and had not yet invaded indigenous forests (Richardson and Brin, 1985). Small individuals were observed in the Cape Fynbos community some years later (Manders and Richardson, 1992) and it could clearly become very invasive there.
P. undulatum is also invading montane evergreen forest in Mauritius.
The species is also abundant in hill forest areas in mainland Portugal and is the most frequent species in wet hill forest near Lisbon.
P. undulatum is on the French Polynesia exclusion list (PIER, 2008) and Australian weed lists, but it is surprising that it does not appear on more such lists considering its invasive nature. However, P. undulatum and many other Pittosporum species are still available and planted as valued ornamental species and further introduction is likely.
P. undulatum is native to warm temperate rainforests, becoming prominent in edaphically drier sites, though within burned rainforest P. undulatum will be eliminated. In the drier parts of the range, however, it may be restricted to moister sites, and it may also be a pioneer species around rainforest patches (Barrett and Ash, 1992). Generally, P. undulatum may be found in a variety of habitats, such as rainforest, scrub/shrublands, watercourses, disturbed areas, and grassland if fire is suppressed, being characteristic in forest margins, open forest and scrub but less common in forest understorey (Goodland and Healey, 1996).
More specifically, P. undulatum in New South Wales occurs sporadically in notophyll vine forests, but is more common on their margins in tall open wet sclerophyll forests (Gleadow and Ashton, 1981). It is found in deep sandstone gullies on the fringes of temperate rainforests in New South Wales, in moist locations higher up the gully sides and on the ridgetops only if there is a low fire frequency, but it may grow large on gully floors as even severe fires usually jump these areas. Previously it was only occasional in open, grassy, tall forests but is now common, shading out almost everything underneath, and is now the most abundant of several rainforest species invading bushland on shales and sandstones, with P. undulatum considered to be seriously out of balance in its natural habitat, requiring control. In Victoria, P. undulatum occurs in microphyll vine forests especially in drier gullies as well as in wet and dry sclerophyll forests (Gleadow and Ashton, 1981). It is largely confined to drier, higher light environments, being the commonest tree seedling in gaps and one of the two principal colonising tree species of open slopes and landslide-disturbed areas, becoming dominant in forest below the slopes but less common in valley bottom forest.
In Jamaica, P. undulatum becomes dominant in secondary forests and natural forest subjected to hurricane damage. It is a common sub-canopy tree and shrub in several forest types and is also widespread in more open habitats (Binggeli and Goodland, 1997).
In the Azores, P. undulatum becomes increasingly dominant from 100 m altitude up to 1000 m, with a gradual transition from open Pinus pinaster dominated woodland to dense P. undulatum forest, making up about half of all trees present at 200-300 m, and being only occasional over 1000 m where frosts occurred.
In South Africa, P. undulatum is invading tall scrub dominated by Olea europaea, Kiggelaria africana, Rhus angustifolia and Maytenus oleoides in Jonkershoek State Forest, and also indigenous riparian forest patches in mountain ravines, with P. undulatum typically clumped around the butts of native trees that bear fruit attractive to birds.
P. undulatum can hybridise with other species in the genus, and has been observed doing this naturally though occasionally in its native range with P. bicolor and possibly P. revolutum (Cooper, 1956). A cultivar has been selected for its growth habit, foliage cover and leaf shape from a P. undulatum x P. bicolor cross, called ‘Cut Above’ (Jackson, 2000). Information on chromosome numbers has not been located.
Reproductive Biology
Sex expression of flowers is somewhat variable but flowers are usually unisexual, with inflorescences containing 1-4 insect-pollinated flowers, powerfully scented at night. Flowering starts at around 5 years of age, enhanced by higher light levels, and fruits take about 6 months to mature. In Jamaica, bees are important pollinators and fruiting is highly synchronised (Goodland and Healey, 1996; Binggeli and Goodland, 1997).
Physiology and Phenology
Blown-down trees sprout vigorously along the trunk, seedlings coppice if the leader is removed, and cut stems will re-sprout if replanted. Seedling recruitment happens mostly after periods of wet weather, and will occur below the forest canopy but increases in higher light intensities such as canopy gaps and forest edges, with seedling densities up to 5000 m-2, though few seeds germinate under P. undulatum canopies. Seed germination is optimal at 18 and 21°C and dropped off steeply at higher temperatures, declining to zero at 30°C. In Jamaica, P. undulatum differs from native species in response to hurricanes by suffering lower mortality, less crown damage and a higher number of fallen trees which readily resprout. The extensive superficial rooting system of P. undulatum is not observed in native species (Binggeli and Goodland, 1997).
Inflorescences develop in terminal positions on leading shoots from December to February, and buds appear in the axils of leaves beneath the inflorescences a few weeks later, some developing rapidly and assuming a leading position, while others develop more slowly and form whorls of lateral branches. Aborted flowers are forced to one side and shed as an axillary shoot takes over a leading position, but with fertilised flowers the vegetative buds remain dormant in the axils of the subtending leaves and the cluster of capsules persists as a terminal structure for as long as 1-3 years (Cooper, 1956; Goodland and Healey, 1996). It can be propagated vegetatively by stem cuttings, and such clonal reproduction is employed when multiplying selected cultivars for ornamental use.
Associations
In its native range, P. undulatum is commonly associated with various Eucalyptus species in a number of specific alliances and sub-alliances, being the second most abundant understorey species in Eucalyptus pilularis forest and common in Eucalyptus botryoides forest as part of the Eucalyptus saligna Alliance. It is the most abundant understorey species in moister areas of the E. pilularis-E. saligna- Eucalyptus paniculata Suballiance, and is also found in the Eucalyptus maculata Alliance and E. pilularis-E. piperita Suballiance. P. undulatum also occurs in Ceratophyllum-Diploglottis forest, Ceratophyllum-Schizomeria forest, Argyrodendron forest and Drypetes forest (Goodland and Healey, 1996). Vesiscular-arbuscular mycorrhizae have been observed on P. undulatum where invasive in Jamaica (Binggeli and Goodland, 1997).
An interesting observation is a possible association with Hedychium gardneranum, another invasive plant, native to the Himalayas, but found growing under the canopy of invasive stands of P. undulatum in the Azores and Jamaica. In Jamaica, Polygonum chinense is also found growing under the canopy (Goodland and Healey, 1996).
Environmental Requirements
The climatic conditions of its native range include a wide range of climates from moist sub-tropical to dry temperate, the latter without a pronounced dry season. At the northern, warmest extreme of its range in southern Queensland (24°S), the mean temperature of the warmest month, January, is approximately 26°C, whereas at the southernmost extreme, the mean temperature of the coldest month, July, is approximately 8°C, with occasional frosts. Mean annual rainfall in its native range is 800-1500 mm, well distributed throughout the year, though it is drought tolerant in parts of its range but also able to withstand seasonal waterlogging (Goodland and Healey, 1996). The range in climates between its invaded and native ranges is considerable, however, and for example, where invasive in the Blue Mountains of Jamaica, mean annual rainfall is 2700 mm or more with a bimodal distribution, and mean monthly maximum temperatures range from 18.5 to 20.5°C, with night-time winter temperature only down to 10°C. It can tolerate an absolute minimum temperature of -5°C for very short periods.
P. undulatum is found on a range of soil types, including alluvial soils, krasnozems, red or yellow podzolic soils, skeletal soils (Gleadow and Ashton, 1981) and also old sand dunes sometimes enduring severe salt spray (Cooper, 1956). It will grow in most well-drained soils of reasonably good quality, however, preferring acidic soils and extra moisture, yet can also withstand extended dry periods once established.
In Australia, approximately ten insects are recorded as feeding on P. undulatum and other Pittosporum spp., listed below, though none are believed to cause serious damage or death or significantly reduce population levels and it is not thought they hold much promise as biological control agents (Binggeli and Goodland, 1997). Pittosporum longicorn larvae (Strongylurus thoracicus) bore round tunnels in the sapwood just below the bark mostly on small to medium-sized branches which may be killed. Pittosporum leafminer (Phytobia pittosporphylli, family Agromyzidae) larvae may become so prevalent in parts that all leaves may be affected, causing discoloured sunken blotches about 1-3 mm across around the midrib, and Phytobia pittospocaulis sp. nov. lives in twig galls. Scale insects can be common, including the native cottony cushion scale (Icerya purchasi) and the exotic pink wax scale (Ceroplastes rubens) and Chinese wax scale (Ceroplastes sinensis). Gall thrips (Teuchothrips pittosporiicola and other Teuchothrips spp.) commonly infest leaves, also several sap suckers including the Pittosporum bug (Pseudapines geminata). The Pittosporum chermid or psyllid (Trioza vitreoradiata) causes small lumps on the leaves, and the Pittosporum beetle (Lamprolina aeneipennis) can cause serious damage to leaves.
Since about 1980, a disease has severely attacked P. undulatum around Cape Town and Stellenbosch in South Africa. A series of personal communications cited in Goodland and Healey (1996) states that the ‘blight’ had been devastating in gardens especially affecting hedge plant. The disease has been welcomed by conservationists in South Africa, and although generally referred to as a viral disease it may be caused by a mycoplasm, and it may have originated on the native P. viridiflorum.
Insects and spider mites on P. undulatum in Colombia and their potential pest herbivorous species as well as their natural enemies are recorded by Lee et al. (2000). P. undulatum suffers some herbivory in Jamaica, and seven different patterns of damage are suspected to be caused by distinct agents (Goodland and Healey, 1996). Pittosporum spp. are notably resistant to honey fungus (Armillaria spp.).
The capsules or seeds are likely to be dispersed down watercourses, and capsules may roll down slopes, though this is likely to be much less important than dispersal by animal vectors.
Vector Transmission (Biotic)
The capsules usually contain 20-40 sticky orange seeds, which are dispersed mostly by ants and birds in its native range. It is thought to be largely bird-dispersed where introduced, such as in Jamaica, where many native birds were observed eating the fruit, and pigs were only rare visitors thus considered less important (Goodland and Healey, 1996; Binggeli and Goodland, 1997). There is also an association with another introduced species in its native range, as in Victoria, Australia: the exotic European blackbird (Turdus merula) is noted as a more effective seed disperser of P. undulatum than any of the native bird species (Gleadow and Ashton, 1981).
Accidental Introduction
P. undulatum is possibly spread via garden waste (Tee et al., 1999), or as a garden escape. The sticky seeds can also adhere to people, and thus may be spread along paths and/or hiking trials during time of capsule dehiscence.
Intentional Introduction
International, long-distance dispersal of P. undulatum has been entirely intentional, being introduced around the world mostly as an ornamental species from the 1800s, but also as a suitable hedge and/or windbreak, such as in the Azores. Its spread outside of its native range in Australia has also been due to its widespread planting in gardens (Gleadow and Ashton, 1981).
Control costs of P. undulatum where it is an environmental weed have not been specifically quantified. There are also effects on water yield and sediment load (Goodland and Healey, 1996) that may have additional economic effects. Positive impacts are possible, as have been noted where invasive in Jamaica, as its greater productivity should have benefits, particularly to local people through the production of fuelwood and timber (Goodland and Healey, 1996). It has also been observed as a possible host plant for citrus aphid, though this has not been confirmed.
In wet sclerophyll forest in early stages of invasion in Victoria, Australia, only one native plant species was found beneath dense clumps of P. undulatum, and in other areas it has been described as very dominant and considered the most serious threat to native forests (Gleadow and Ashton, 1981). The depressive effect on native vegetation and the significant impacts to forest structure has led to P. undulatum being controlled in many nature reserves and parks in Australia. In southern Australia, P. undulatum has established in new areas and causes a serious reduction in floristic and structural diversity (Gleadow and Narayan, 2007). Also in Victoria, Mullett and Simmons (1995) observed a reduction in the cover and abundance of indigenous species with increasing cover and abundance of P. undulatum concluding that shade is likely to be the primary factor, and along with secondary impacts, indicating that P. undulatum poses a very serious threat to the ecological sustainability and integrity of remnant vegetation complexes in Victoria as the species continues to increase both its range and local densities. Vigorous growth of the naturally occurring P. undulatum x P. bicolor hybrid in Victoria, Australia is also resulting in serious ‘swamping’ of P. bicolor via hybridisation (Goodland and Healey, 1996).
Around Sydney, New South Wales, P. undulatum and other invasive exotic plants caused substantial decreases in native species richness to the point of elimination in older suburbs, including one vulnerable taxon (Tetratheca glandulosa) (Rose and Fairweather, 1997). Rose (1997) observed that suburban edges exert a major influence on invasion of the native P. undulatum in dry sclerophyll bushland in the same area, which had seen significant increases of P. undulatum over 90 years, and floristic and structural simplification appear to be the principal impacts exerted on the vegetation composition at invaded sites. There is also an observed additional environmental side-effect, however, that by publicly calling P. undulatum a weed in its native range, this puts at risk scarce remnants of indigenous vegetation, as people may cut the tree in areas where it is truly indigenous thus causing a reduction in local biodiversity (Howell, 2000).
Where introduced and invasive in Jamaica, P. undulatum is able to grow at higher densities than any native species and, combined with its dense crown, achieves dominance and appears to reduce the survival and growth of even shade-tolerant native species (Goodland and Healey, 1996). It has a serious impact on all native vegetation types, though it invades them at different rates, and in areas invaded by P. undulatum a sharp decrease in native species richness has been recorded probably caused by the dense shade it casts (Binggeli and Goodland, 1997). P. undulatum impacts on native vegetation via shading, below ground competition, nutrient cycling, allelopathy, and indirect effects, and although the impacts on animals and ecosystem processes are likely to be negative they are almost completely unresearched (Goodland and Healey, 1996). It can also affect water available in South Africa (Smith, 1990). Also, in the Azores, Portugal, the Azores bullfinch (Pyrrhula pyrrhula murina) is known to exist only in the east of São Miguel island where it is largely confined to native laurel (Laurus azorica) forest, but its population and distribution has been impacted on by large-scale invasion by exotic flora, mainly P. undulatum, Hedychium gardnerianum and Clethra arborea, which followed clearing the forest for pasture and afforestation by P. undulatum and another exotic, Cryptomeria japonica (Ramos, 1996).
In the suburbs of Sydney and Melbourne, P. undulatum continues to spread as a weed, and may impact on local aesthetics and even land values, though no data are available. In the Blue Mountains of Jamaica in August-December, the orange capsules can be so abundant on P. undulatum trees that they can be seen from over two kilometres away, colouring whole hillsides, so that the characteristic colours and textures of the natural forest are lost, especially to most hikers who are probably attracted as much by the prospect of long-distance views as by the appearance of trail side forest (Goodland and Healey, 1996).
P. undulatum makes very good firewood, produces excellent charcoal and is a useful all purpose timber. One of its popular names in Australia is ‘engravers wood’ and it was the preferred wood for golf clubs in Australia in the early 1900s, and was used as a source of carving wood in Jamaica, as well as fuel and construction poles. Goodland and Healy (1996) estimated its value as US $27/m3 as fuel wood, US $40/m3 for charcoal, and US $410/m3 as sawn timber. It also has potential as a source of essential oils in Brazil (Ferreira et al., 2007), and was also considered for this use in Australia and California though no further information is available. The fruit of P. undulatum was once of particular interest as a source of terpenes for use as a fuel oil. In St Helena, P. undulatum is pollarded and fed to stalled goats and cattle. Abundant nectar production also makes it good for honey bees.
Due to its fragrant and attractive flowers it is a respected ornamental plant in its native Australia and also where introduced, such as in Italy (Cacciola and Polizzi, 1996) and elsewhere, being once described as one of the handsomest flowering trees of Australia, and because the rich perfume of its white blossoms extends over a considerable area.
It is also a hedging plant and is used as a windbreak, and as a living fence in Colombia (Lee et al., 2000).
Two other Pittosporum species, P. tobira and P. viridiflorum are regarded as potentially to moderately invasive in the Pacific (PIER, 2008). P. undulatum hybridizes with Pittosporum bicolor and this hybrid is intermediate between the two species.
P. undulatum can be confused with other Australian native species such as Auranticarpa rhombifolia and Rapanaea howittiana. These species can be separated by the following differences (Weeds of Australia, 2015):
Pittosporum undulatum has leaves with entire margins and relatively large creamy white flowers (1-2 cm long). Its fruit are relatively large orange capsules (10-15 mm across) that split open when mature.
Auranticarpa rhombifolia has leaves with toothed (i.e., serrate) margins (rarely entire) and relatively small white flowers (6-8 mm long). Its fruit are relatively small orange capsules (4-6 mm across) that split open when mature.
Rapanea howittiana has leaves with entire margins and tiny creamy white flowers. Its fruit are relatively small blue or purplish 'berries' (5-7 mm across) that do not split open when mature.
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
Control
Cultural control and sanitary measures
P. undulatum is known to be excluded by fire, and thus controlled burning is a potential means of control. Gleadow and Narayan (2007) found that temperatures of 90-120°C would cause seed mortality and that most seed stored in the canopy would be killed by controlled burning, and in addition, 90% of seedlings around 0.4 m tall were killed when heated to 180°C for 5-10 min. However, 20% of the mature trees re-sprouted within 6 months of the fire, though the temperatures associated with fires are sufficient to act as a circuit breaker on the invasion cycle allowing other control measures to be employed to greater effect (Gleadow and Narayan, 2007). Fire was also considered in Jamaica (Goodland and Healey, 1996).
Hutton (2001) proposes a novel means for control of P. undulatum, on Lord Howe Island off the coast of Queensland, Australia, as a part of eco-tourism development, where visitors came to learn about local ecology while also weeding trees and assisting in physical control.
In the Azores, sheep grazing was noted as reducing the rate of invasion of P. undulatum into Myrica faya-Persea azorica woodland.
Physical/mechanical control
Hand pulling of seedlings is effective, and when attempted in Jamaica, even though about 60% of the roots of uprooted seedlings snapped, none of these detached roots re-sprouted, however, about half of the uprooted seedlings left on the soil surface survived so they would need to be collected.
Biological control
Biological control has not been attempted.
Control by utilization
P. undulatum is a valuable tree in some areas as a source of wood products, and several authors have noted the potential as control by utilization, notably in the Azores and Jamaica. Branches and stems have been processed into wood chips which have been composted in the Azores (Batista et al., 2000), but if composting plant parts, adequate turning is required to ensure that all parts are exposed to temperatures in excess of 55°C for 3 days (Tee et al., 1999). Also, use of chopped branches was found as the best soil amendment for pineapple production in Azores, but sawdust was also beneficial (Tavares, 1997).
Managers in the Blue Mountains National Park, Jamaica, have expressed their strong desire to discover ways of managing the P. undulatum invasion to protect the park’s diversity whilst simultaneously benefiting the people who live in the surrounding area as there will almost certainly be an increasing shortage of fuel and building materials in the future (Goodland and Healey, 1996). There is a great need to develop new sources of these essential goods and P. undulatum certainly has potential, particularly as a timber tree and source of charcoal. There is already a substantial volume of P. undulatum wood and this volume is increasing rapidly and the much higher value of sawn timber over firewood or charcoal means that any trees large enough (>20 cm diameter) and of satisfactory form should be used for that purpose (Goodland and Healey, 1996). In their comprehensive and detailed report, Goodland and Healey (1996) concluded that allowing small-scale harvesting in heavily infested stands and developing markets for P. undulatum timber were two of the seven methods for best managing this invasion.
Monitoring and Surveillance
In Jamaica, park managers need more detailed information on the location of isolated P. undulatum trees and populations than exists at present. Observation of hillsides being invaded by P. undulatum suggests that it would often be difficult to detect P. undulatum trees before they reach the canopy, by which time they may have already started producing seeds (Goodland and Healey, 1996).
Ecosystem Restoration
The very high recruitment of P. undulatum and the generally low recruitment of other species following the removal of P. undulatum trees has been noted in Jamaica (Goodland and Healey, 1996), which are likely to be major problems with re-vegetation and restoration efforts following control efforts. Furthermore, gap formation following cutting promotes the regeneration of P. undulatum and other alien weeds, notably Polygonum chinense and Hedychium gardnerianum (Binggeli and Goodland, 1997).
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