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Pittosporum undulatum

Evergreen shrub or tree, with dark green leaves, white flowers and orange fruits.

Scientific name: Pittosporum undulatum Vent.

Common names: pittosporum, sweet pittosporum, Australian boxwood, cheesewood

Family: Pittosporaceae

Status in Portugal: invasive species (listed in Decreto-Lei nº 92/2019, 10 julho)

Risk Assessment score:  25 | Value obtained according to a protocol adapted from the Australian Weed Risk Assessment (Pheloung et al. 1999), by Morais et al. (2017), according to which values above 13 mean that the species has risk of having invasive behavior in the Portuguese territory | Updated on 30/09/2017.

Last update: 01/07/2021

Family: 
Pittosporaceae
Appearence: 
Trees and shrubs

How to recognise it

Shrub or small tree up to 15 m, with a grey rhytidome.

Leaves: evergreen, petiolate, ovate–lanceolate, acute, of 5-15 x 1,5-4 cm, glabrous, with an undulated margin, alternate or grouped in the branches’ termination.

Flowers: white, aromatic, arranged in cymes that look like umbels.

Fruits: obovate to sub-globular capsules, glabrous, with 2 valves, orange when ripe. Orange seeds wrapped by mucilage.

Flowering: March to June.

 

Similar species

It may be confused with bay laurel (Laurus nobilis L.), but this tree has a strong aroma, black berries, the leaves have a shorter petiole and the margins aren’t undulated. It can rarely be confused with the leaves of laurustinus (Viburnum tinus L.), while young, but it presents tufts of hairs on the vein axils of the lower surface.

 

 

 

 

Characteristics that aid invasion

It propagates vegetatively, forming vigorous sprouts from the stump or roots after being felled.

It also reproduces by seed, producing many seeds (up to 37500 seeds/tree), that are dispersed by animals, mainly birds.

Native distribution area

Southeast Australia.

 

Distribution in Portugal

Mainland Portugal (Beira Litoral, Baixo Alentejo, Estremadura), Azores archipelago (all islands), Madeira archipelago (Madeira island).

 

Geographic areas where there are records of Pitosporum undultum

Other places where the species is invasive

Europe (Spain), South Africa, North America (Mexico, USA), central America (Cuba), Australia, New Zealand.

 

Introduction reasons

For ornamental purposes in gardens, urban forestation and hedges.

 

Preferential invasion environments

Managed areas (e.g., Bussaco National Forest, Sintra Mountains), where it was planted as an ornamental plant, roadsides and ruderal locations.

It develops well in the shade, even though it’s a shade-intolerant species.

It does not demand generally favourable soil conditions; it thrives along coastal areas and over calcareous terrains.

Impacts on ecossystems

It forms very dense populations inhibiting the development of native vegetation.

The leaves produce toxins that may hamper the development of native vegetation.

 

Economic impacts

Expensive control methods.

 

Natura 2000 network habitats more subject to impacts

– Riparian mixed forests of Quercus robur, Ulmus minor and Fraxinus angustifolia, along the great rivers (91F0);
– Arborescent matorral with Laurus nobilis (5230);
– Quercus faginea and Quercus canariensis Iberian woods (9240).

Controlling an invasive species demands a well-planned management, which includes the determination of the invaded area, identifying the causes of invasion, assessing the impacts, defining the intervention priorities, selecting the adequate control methodologies and their application. Afterwards it is fundamental to monitor the efficiency of the methodologies and recuperation of the intervened area as to perform, whenever necessary, the follow-up control.

The control methodologies used for Pittosporum undulatum include:

 

Physical control

Hand pulling: preferential methodology for seedlings and small plants. When in more compacted substrates, hand pulling must be made during the rainy season as to facilitate the removal of the root system. It should be guaranteed that no stumps and main roots are left in the ground.

Ring-barking: preferential methodology for adult plants with a smooth, unwounded bark. Make a continuous ring incision around the trunk, at the height most comfortable for the operator, and remove all the bark and vascular cambium to ground level or, if possible, to the root. It should be applied only when the vascular cambium is active, which may vary from place to place; the best seasons for this technique coincide with warm temperatures and some humidity.

 

Physical + chemical control

Cut stump method: applied to adult plants. Cut the trunk as close to the ground as possible and immediately (in the following seconds) apply herbicide (active substance: glyphosate) to the cut stump. If shoots should latter on appear, these should be immediately eliminated through cutting, pulling or foliar application of herbicide (active substance: glyphosate); up to 25 to 50 cm high. Shoots of larger dimensions (from 2-3 cm diameter) may ring-barked off or else should be repeated the initial methodology (cut stump method).

 

Chemical control

Stem injection: applied to adult plants. Apply the herbicide directly on the vascular system by drilling holes (with a drill) 10 cm deep around the trunk and in each hole immediately inject (in the following seconds) the herbicide (1 ml) with a squirt bottle. The holes should be made at a height most comfortable to the operator, in a 45º angle (to avoid the herbicide’s runoff) and in intervals of 5-10 cm between them. The number of holes to make depends on the plant’s diameter.

 

Prescribed fire

It may be strategically used to favour germination of the seed bank, e.g., after the control of adult individuals (with the adequate management of the resulting biomass) or and the subsequent elimination of seedlings. This method provides an advantageous reduction of the seed bank, both by destroying part of the seeds or by stimulating the germination of the remainders.

 

Visit the webpage How to Control for additional and more detailed information about the correct application of these methodologies.

CABI (2012) Pittospotum undulatum. In: invasive">Invasive species">Species Compendium. CAB International, Wallingford, UK. Available: http://www.cabi.org/isc/ [Retrieved 06/11/2012].

 

 

Global invasive">Invasive species">Species Database (2005) Pittosporum undulatum. Available: http://www.issg.org/database/species/ecology.asp?si=344&fr=1&sts=&lang=EN [Retrieved 16/11/2012].

 

 

 

 

I3N Brasil (2012) Base de dados nacional de espécies exóticas invasoras. Pittosporum undulatum. Instituto Hórus de Desenvolvimento e Conservação Ambiental, Florianópolis – SC. Available: http://i3n.institutohorus.org.br [Retrieved 06/11/2012].

 

 

 

 

Marchante E, Freitas H, Marchante H (2008) Guia prático para a identificação de plantas invasoras de Portugal Continental. Imprensa da Universidade de Coimbra, Coimbra, 183pp.

 

 

 

 

Silva L, Corvelo R, Moura M, Coello RM, Carvalho JA (2008) Pittosporum undulatum Vent. Br. In: Silva L, Land EO, Luengo JLR (eds) Flora e fauna terrestre invasora na Macaronésia. Top 100 nos Açores, Madeira e Canárias. Arena, Ponta Delgada, pp. 225-228.