Delissea undulata is an extremely rare species of "palmoid" or 'Corner model tree"[further explanation needed] presently confined to the Big Island of Hawai'i, mostly in botanical gardens.

It is in the subfamily Lobelioideae of the family Campanulaceae.

The tree is up to 35 ft (11 m) in height but only 2 in (51 mm) in diameter at breast height (DBH).

The terminal rosette of leaves is only 18 in (460 mm) across.

The flowers are tubular and straight.