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.