In today’s THE FEATURED PLANT section we will talk about Pittosporum tobira (P. tobira), a highly branched shrub or tree, up to 6 m high, with evergreen, leathery, often spatulate leaves, shiny dark green on the underside. Its flowers are pentamerous, white or yellowish, and the fruits are rounded, woody, which open in three valves, exposing reddish seeds that are very attractive to birds. P. tobira is native to East Asia, in southeast Korea, southern Japan, Taiwan and eastern China. You can read its file here.
It is grown as a shrub or ornamental tree in urban or private gardens or to make living fences and road medians as it is very hardy, low maintenance and always with dense green foliage. It was introduced in Europe in 1804 in the gardens of London and has been in the Iberian Peninsula since the end of the 19th century. Its long coexistence with man, of more than two centuries, makes it surprising to many that this plant is an introduced species.
It grows in various types of environments, from rather shady and humid areas to others with high sun exposure and low water availability. Its tolerance to a certain degree of salinity makes it widely distributed in coastal areas, often in places of anthropogenic influence. It can be found in disturbed pine forests or near inhabited or human-influenced areas – isolated or widely scattered individuals – naturalised or with invasive behaviour.
This species is not included in the Spanish Catalogue of Invasive Species at the peninsular level (it is only considered as such in the Balearic Islands). Despite this, it is clearly invasive, especially in the coastal area of Catalonia. In fact, on the Costa Brava it is one of the five most observed species by the LIFE medCLIFFS Observers Network (417 observations).
It has a great capacity for growth and propagation, in this case especially due to the fruit-eating birds that consume the seeds and disperse them over a certain distance. This explains why it is found very frequently both on coastal cliffs and in areas of scrubland or nearby pine forests where it can form an important part of the undergrowth or even part of the woodland areas.
From the observations during the preparatory phase of the LIFE medCLIFFS project and those of the volunteers, we have already seen that it is a frequent species along many stretches of the coastal path. In fact, there are some known citizen participation actions of P. tobira removal in Catalonia, including the Costa Brava. An article was also published two years ago explaining the monitoring of the P. tobira in the Llobregat Delta, concluding that it is a highly invasive species that causes serious damage to the native flora and to natural and semi-natural habitats (Açaí et al., 2022). This species is also naturalised in the same Mediterranean cliff habitat further south in Catalonia.
In short, we must consider the P. tobira as an invasive species which, although it was introduced into our environment a long time ago, is still expanding. This consideration does not exempt it from being a very attractive shrub/tree due to its foliage and shade, but we must be alert to the fact that it continues to increase its area of distribution, especially in natural areas.
Text: Carlos Gómez-Bellver.