The leaves of formosa lily are lance-shaped, reaching up to 8 inches (20 cm) in length. They are a vibrant green color, which contrasts with the tall, slender stems. The leaves are smooth to the touch with a pointed tip, arranged alternately along the stem. The veins are parallel, which is characteristic of monocots. Each leaf has a glossy surface, enhancing its striking appearance. These features make the leaves valuable for identification.

The flowers of formosa lily are trumpet-shaped, featuring six petals and measuring 6-10 inches (15-25 cm) in length. They are predominantly white, occasionally tinged with reddish-purple hues. These flowers often appear in clusters, either in pairs or umbrels of up to 10 blooms on a single stem, making them visually striking. The combination of their size, color, and distinctive petal arrangement makes them easily recognizable to plant enthusiasts.

The stem of formosa lily is prominently stiff and green, measuring up to 4 feet (120 cm) tall. It is cylindrical, smooth, and has a robust texture that supports the plant's height. The stem's green coloration remains vibrant throughout its growth stage, contributing to its distinctive appearance. It has a moderate thickness, approximately 0.5 inches (1.3 cm) in diameter, with minimal branching, offering a straightforward, unbranched form that aids in easy identification.

The fruit of formosa lily is typified by upperward facing seedpods, which are valued for their aesthetic contribution to gardens and dried floral arrangements. These seedpods are elongated, and as they mature, they transition from a vibrant green to a brown coloration, offering a striking visual display. The texture, while initially smooth, becomes more papery and brittle as the pods age and dry out. Upon reaching maturity, each pod splits open to reveal numerous flat, winged seeds that are dispersed by the wind. The seedpods measure approximately 3 to 6 inches (7.5 to 15 cm) in length, making them a notable component of the plant's reproductive system.