Biology:Pisonia umbellifera

Short description: Species of tree

Pisonia umbellifera
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Order:	Caryophyllales
Family:	Nyctaginaceae
Genus:	Pisonia
Species:	P. umbellifera
Binomial name
Pisonia umbellifera (J. R. Forster & G. Forster) Seemann

Pisonia umbellifera, commonly known as the birdlime tree or bird catcher tree, is a species of plant in the Nyctaginaceae family. It grows throughout the tropical Indo-Pacific. It is native to the Andaman Islands, Indonesia, Malaysia, the Philippines , Thailand, Vietnam, China , Taiwan, Hawaii, Africa and Madagascar and the states of New South Wales and Queensland in Australia . A variegated form is widely cultivated in frost-free climates.

P. umbellifera 'Variegata'

It's genus is named after a Dutch scientist, Willem Piso, and 'umbellifera' is derived from Latin umbelliferum, denoting the species' big, 'shade-carrying' foliage.

Description

The ‘pisonia umbellifera' is a shrub with large, medium green leaves. Other variegated varieties exist (pisonia umbellifera variegata) with marbling of white, light and dark green on the shrub’s leaves. The tree’s elliptic leaves may be between 6 to 20cm long, and 4 to 10cm wide.

There are discrepancies between sources regarding the height of the shrub. Most state that pisonia umbellifera will grow to between 4 and 12 metres. Some sources suggest the tallest known specimen is 20 metres tall, whilst another reports a height of 28 metres. Once mature, the tree has a spreading, rounded crown5 which may cover over 20 feet.

In summer, the tree will start to bud and produce flowers. Before blooming, the buds of the flower stem from a complex inflorescence. Buds are around 6cm in height, and have a pale brown, chickpea-like appearance. The flowers consist of small pink or yellow petals in a rounded funnel formation, with short white stems protruding from the centre. The flowers are very fragrant.

After flowering, the shrub produces small fruit. These are the colloquial namesake of the tree, which is also known as ‘birdlime’; due to the fruit’s secretion of a sticky substance, small birds may often become ensnared in this substance and are unable to fly away. The viscid fruit are dark brown and purple, cylindrical in shape and about 2-4 cm long. They are vertically ribbed. Both the leaves and fruit are hairless.

Distribution and Habitat

Distribution

Pisonia umbellifera may be found in a diverse range of climates worldwide. The plant is native to Australia, Southern China, Thailand, Vietnam, Taiwan, Malaysia, Philippines, Indonesia, Hawaii and many Polynesian islands. It is also naturally occurring in some parts of Africa and Madagascar.

In Australia, the species is found along the east coast in the states of New South Wales and Queensland, where it is ‘widespread, but not common’. In NSW, it is found along the North Coast and Central Coast regions. It mostly grows in rainforests north of the Shoalhaven region.

In Hawaii, pisonia umbellifera is known as ‘pāpala’ or ‘pāpala kēpau’. It is particularly endemic in the areas of Kauaʻi, Oʻahu, Lānaʻi and Maui, but has also be found on mainland Hawaii and Molokaʻi. In Hawaii, the species will be found in areas receiving “50-100 inches” of rainfall annually and in regions between “150-1999” feet above sea level.

Habitat

Generally, its ideal growing conditions are between about 16 and 20 degrees Celsius. It may only be grown in frost-free environments and gardens, and similarly will not tolerate sustained heat. However, some rare accounts describe the tree surviving to as cold as 26 degrees Fahrenheit.

The plant requires high humidity and moderate moisture, although "established plants are drought tolerant”. Most often, reliably moist soil with high potassium is needed, but the species will survive dry soil with occasional watering.

Moderate amounts of sunlight are needed, with most growing instructions designating part shade or full sun. When grown as an indoor plant, gardeners suggest “four hours of direct sunlight ... bright light the rest of the time”.

In the wild, pisonia umbellifera is often found in rainforests, on islands and along coastlines and in shady, moist gullies. Therefore, it is largely found in countries with tropical regions.

Ecology

The fruit of pisonia umbellifera exude a sticky sap, which often sticks to wildlife passing by the tree. Small animals, such as birds, reptiles and insects are often trapped in the substance and starve to death.

Largely it is seabirds, dwelling on off-shore islands, that die in the fruits of the shrub. However, there are some accounts of mainland birds becoming stuck. Scientists in the Goldsborough Valley, south of Cairns in Queensland, Australia, discovered a female Buff-breasted Paradise Kingfisher who was “completely immobilised, unable even to flap her wings”.

It is generally agreed that the tree’s birdlime is an adaptation, enabling the tree to pollinate; pollen will adhere to a bird, and be deposited somewhere else, where a new plant may grow. However, some botanists suggest that the extreme stickiness may have evolutionary advantages outside of pollination.. Since pisonia umbellifera is widespread on tropical island rainforests, it is plausible that when the plant “traps and kills animals” it is "creating pockets of nutrients in the immediate soil environment for seedlings”. This is especially important on islands because often their soil is not as fertile and nutrient rich.

Gould's Petrels

The tree presents a threat to the Gould’s Petrel population on Cabbage Tree Island, since the birds are classified as a threatened species. Petrels’ entanglement in the viscous fruit sap has been identified as a major cause of mortality by Australian ornithologists. In some cases, a single fruit was enough to trap a bird and cause its death. During 1992 and 1993, some of the pisonia umbellifera plants on Cabbage Tree Island were subject to herbicide poisoning, in an attempt to reduce the threat to Gould’s Petrels and improve their endangerment status. This was largely successful, although other natural threats to the petrel remain.

Uses 

Traditional Medicine

In Hawaii, the tree was used for a variety of purposes by early indigenous people. Leaves of pisonia umbellifera is used as a general purpose medicine for digestive issues and childhood disease.

In their paper on saponins found in the shrub’s leaves, Lavaud and Beauvir state that “In Vanuatu, the leaves of P. umbellifera are also used as a treatment for ciguatera poisoning and as a 'green manure'.

Research and Technology

Potential medicinal properties of pisonia umbellifera have been the subject of scientific investigation. One study found that compounds extracted from the leaves of pisonia umbellifera could have ‘antitubercular activity’ under certain circumstances.

Culture

In Hawaii, the tree’s leaves and bark are also used as a stable source of food for pigs.

The adhesive sap from the fruit is also commonly used by indigenous Hawaiians. The sap may be made into a paste with okra and used to mend broken bowls. Additionally, it is used by indigenous men to catch birds, from which the feathers are plucked and used for traditional garments.

See also

• Birdlime

References

Wikidata ☰ Q3725162 entry