Pisonia grandis is a species of flowering

Flowering plant

The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...

 tree

Tree

A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

 in the Bougainvillea

Bougainvillea

Bougainvillea is a genus of flowering plants native to South America from Brazil west to Peru and south to southern Argentina . Different authors accept between four and 18 species in the genus...

family, Nyctaginaceae

Nyctaginaceae

Nyctaginaceae, the Four O'Clock Family, is a family of around 33 genera and 290 species of flowering plants, widely distributed in tropical and subtropical regions, with a few representatives in temperate regions...

.

Description

The tree has broad, thin leaves, smooth bark and bears clusters of green sweet-smelling flower

Flower

A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

s that mature into sticky barbed seed

Seed

A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

s.

Dispersal

Seed dispersal

Seed dispersal is the movement or transport of seeds away from the parent plant. Plants have limited mobility and consequently rely upon a variety of dispersal vectors to transport their propagules, including both abiotic and biotic vectors. Seeds can be dispersed away from the parent plant...

 occurs when seeds stick to bird feathers. Vegetative reproduction

Vegetative reproduction

Vegetative reproduction is a form of asexual reproduction in plants. It is a process by which new individuals arise without production of seeds or spores...

 frequently results when fallen branches sprout or basal shoot

Basal shoot

A basal shoot, root sprout, adventitious shoot, water sprout or sucker is a shoot or cane which grows from a bud at the base of a tree or shrub or from its roots. This shoot then becomes, or takes the form of, a singular plant. A plant that produces suckers is referred to as surculose...

s develop into new trees.

Distribution

Pisonia trees are distributed throughout the coral

Coral

Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...

 cay

Cay

A cay , also spelled caye or key, is a small, low-elevation, sandy island formed on the surface of coral reefs. Cays occur in tropical environments throughout the Pacific, Atlantic and Indian Oceans , where they provide habitable and agricultural land for hundreds of thousands of people...

s of the Indian

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 and Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

s. The species often dominates mature coral cay vegetation

Vegetation

Vegetation is a general term for the plant life of a region; it refers to the ground cover provided by plants. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader...

, growing in dense, thick strands up to 20 m (65.6 ft) tall. Pisonia wood is rather weak and soft and decays rapidly when the trees fall.

Pisonia forests are a common nesting site for seabird

Seabird

Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...

s. One of the best remaining Pisonia forests can be found on Palmyra Atoll

Palmyra Atoll

Palmyra Atoll is an essentially unoccupied equatorial Northern Pacific atoll administered as an unorganized incorporated territory by the United States federal government...

.

St. Pierre Island

St. Pierre Island

St Pierre Island is a raised reef island west of Providence Atoll and part of Farquhar Group, which belongs to the Outer Islands of the Seychelles. The island is located 35 km west of Cerf Island of Providence Atoll, 704 km from Mahé and 500 km ENE of Aldabra...

, Farquhar Group

Farquhar Group

The Farquhar Group belong to the Outer Islands of the Seychelles, lying in the southwest of the island nation, more than 700 kilometres southwest the capital, Victoria, on Mahé Island. The total land area of all islands in the group is less than 11 km², but the total area of the atolls measures...

, was once covered by a Pisonia grandis forest. This forest disappeared after guano

Guano

Guano is the excrement of seabirds, cave dwelling bats, and seals. Guano manure is an effective fertilizer due to its high levels of phosphorus and nitrogen and also its lack of odor. It was an important source of nitrates for gunpowder...

mining between 1906 and 1972. The natural vegetation had to be destroyed in order to scrape the guano and the island's landscape became barren.

External links

• Nature Seychelles - Seabird deaths caused by P. grandis. Accessed 11 May 2007.