commonly known as the Puerto Rican Hat Palm, is a species of fan palm that is endemic to Puerto Rico and the Dominican Republic. The common name derives from its traditional use in making hats.

This palm tree can grow quite tall, reaching heights of up to 50 feet (15 meters) with a wide canopy. Its leaves are fan-shaped, large, and deeply divided. The leaf stems are long and robust, ending in a sharp point. The leaf bases create a cross-hatched pattern on the trunk when they fall off.

Sabal causiarum produces small white flowers on inflorescences that extend beyond the leaves. The fruits are small, round, and black when ripe. They are a food source for wildlife and can also be used to propagate the palm.

Like many other types of palms, the Puerto Rican Hat Palm prefers a sunny location and well-drained soil. It's quite hardy and resistant to cold, drought, and salt, making it a good choice for coastal landscapes. It can also tolerate a range of soil conditions, including alkaline soils.

This palm is not just ornamental but also has several uses. Besides hat-making, the leaves can be used for thatching and the hard wood of the trunk for construction. The edible fruits can be used to make jelly or fermented into wine. It's worth noting that over-harvesting for these uses can put pressure on natural populations, so sustainable practices are important.