S. cinereum is a tree that can grow up to 10 meters tall, with a twisted trunk and dark gray bark. It often grows in clumps (with several trunks) unlike Sideroxylon puberulum (red mangrove), which has only one. The young leaves are brownish, turn dark green and harden to finally turn an orange-red hue before falling. They have a densely netted venation and a noticeable midrib on the underside. The inflorescence occurs directly on the branches with tightly packed small red flowers. These hermaphroditic flowers produce spherical fruit containing an abundant white latex and a globose seed. This powerful latex helps the tree defend itself against termite attacks.
The green manglier is a pioneer and endemic plant of Mauritius. It is home to the endemic (daytime) gecko Phelsuma ornata which feeds on the nectar of its flowers and helps to pollinate them. The fruit are dispersed by birds which facilitates the dissemination and germination of seeds.
S. cinereum is commonly found in intermediate and upland forests. It is listed as ‘Vulnerable’ on the IUCN Red List of Threatened Species. Unfortunately, the size of its population is decreasing due to the invasion of exotic plants. The species is widely propagated in the nursery for ecological restoration and landscaping.
Green mangrove wood is hard, heavy and durable. It was used in construction for the manufacture of floors, poles, planks and paneling, and especially for the manufacture of boat keels.
Rachel Atkinson and Jean-Claude Sevathian, A guide to the plants in Mauritius, (Mauritius: Mauritian Wildlife Foundation, 2005), 80