Sabal causiarum aka Puerto Rican Hat Palm

Sabal causiarum is an evergreen tree in the palm family. Its common name is Puerto Rican hat palm. It grows wild in the Caribbean, from southern Hispaniola to the Virgin Islands. Its range includes Haiti, the Dominican Republic, and Puerto Rico. It grows in a wet tropical climate. Wild plants can form large, dense stands on sandy coastal plains. These stands occur from sea level to 984 feet [300 metres].

This palm has one thick trunk with no branches. Reported garden heights range from about 26–33 feet [8–10 metres]. Unusually tall plants can reach 52 feet [16 metres]. The trunk measures about 1.1–2.3 feet [0.35–0.7 metres] across. A crown of 20–30 leaves tops the stout stem. The blue-green leaves are costapalmate, with a rib extending into each fan. Each leaf spans about 3–6 feet [0.9–1.8 metres]. Leaf stalks can reach nearly 8 feet [2.4 metres] long. The broad fans and thick trunk define its form.

In gardens, this palm needs sun and soil that drains well. Once its roots are established, it can withstand drought. Its wet tropical origin does not mean it needs waterlogged soil. Growers plant it as an ornamental in tropical and subtropical regions. It also grows in gardens beyond its native range. Its large leaves and stout stem give it a strong shape. Seed provides a means of raising new plants.

People gather its leaves from wild plants for woven goods. They also plant it near homes to provide leaf material. Young leaves supply the straw used for Puerto Rican hats. Makers cure, bleach, and dry the leaves before using them. Leaf fibres also go into baskets, mats, and hammocks. Older leaves provide material for thatched roofs. Useful Tropical Plants lists no known food or medicinal uses. It also reports no known hazards, rather than confirmed safety.

Wild populations face pressure despite the palm's use in gardens. Building and other development reduce the land where it grows. Illegal collection of plants and seeds adds to these threats. Useful Tropical Plants reports a Vulnerable IUCN listing from 2018. It states that each known wild subpopulation has at most 1,000 mature plants. The full effect of wild harvest still needs study.