Mangroves @ Osprey House

Mangrove is a generic name for shrubs and trees that grow in the intertidal zones of tidal estuaries. Worldwide, there are about 65 species of mangroves (belonging to 20 families). Eight species are found in Moreton Bay Marine Park, and three of these occur in the Osprey House environs. These are: the Grey Mangrove, the River Mangrove, and the Red Mangrove.

Grey Mangrove (Avicennia marina)

Grey MangroveThe Grey Mangrove can grow to 15 metres high and is the most common species growing here. It has grey/white bark & opposite leaves. A distinctive feature is their pneumatophores - aerial roots (peg roots) which grow vertically from the surrounding mud. These roots contain spongy tissue which enables them to exchange gases with the air through lentice - thus allowing them to ‘breathe’ at low tide. Grey Mangrove Leaves
Grey Mangrove PneumataphoresGrey Mangroves can tolerate more saline conditions than most other mangroves – in fact their sap may be up to one tenth as salty as sea water. They are light green on the underside and sometimes appear "grey" when compared to the bright green on their upper surfaces. They produce small, fragrant orange/yellow flowers that give rise to an almond shaped / sized fruit encased in a velvety skin. The seeds germinate while attached to the tree (a process called vivipary), which allows for quick establishment once the seed disperses. Grey Mangrove Fruit

River Mangrove (Aegiciceras corniculatum)

River Mangrove HabitatThe River Mangrove is a small multi stemmed shrub that grows to 4 metres high and occurs on the higher end of the intertidal zone. It will tolerate occasional submersion in salt or fresh water as their root system is similar to any other dry land tree. The leaves have a rounded shape and grow alternately on the stem. The leaves have glands that secrete salt from their upper surfaces.River Mangrove Leaves
River Mangroves FlowersThe River Mangrove has small white flowers that grow in clusters and release a perfume not unlike ripe bananas. The single seeded fruit is horn like in shape and it is from this that the secondary scientific name is derived. Cornicula is Latin meaning ‘hornlike’.River Mangrove Fruit



Red Mangrove (Rhizophora stylosa)

Small Stilted Mangrove

The fruit of the Red Mangrove is long and has a "bean-like" shape. When ripe these propagules will drop into the water and float (sometimes for up to a 1 year) in anticipation of spearing into mud to stake claim on an area.

 

The Red (Stilted or Spotted) Mangrove is a small tree that grows to six metres high with distinctive arching roots, sometimes called stilts or prop roots. It has large dark green leaves with numerous small brown spots on the underside that grow in clusters on the end of each branch. The name Red Mangrove (which has become the accepted common name for this species in Australia), may refer to the slightly reddish hue of its trunk.

 

Stilted Mangrove Fruit