A singular North American genus remarkable for the ternary arrangement of the organs, all the species having the net-veined leaves in verticils of threes, the perianth in two distinct series, the outer sepaloid and persistent and the inner petaloid and fugacious, 3 or 6 stamens and 3 stigmas and a 3-celled fruit. This genus and its allies are referred by some writers to Smila-clnew, whilst others regard them as a tribe of the Liliacew. The name is from the Latin trilix, triple. Two or three tuberous-rooted species are in cultivation, but they are seldom seen.

1. T. grandiflorum. - A very beautiful plant about a foot high with ovate strongly-nerved leaves and solitary terminal pedunculate flowers. Outer segments of the perianth green, and the inner ones white.

2. T. pendulum, syn. T. erectum. Birthroot.- This differs mainly from the last in the rounded base of the leaves, which are abruptly acute. The flowers are violet in the type, but there is a white-flowered variety.