Editing Trillium (section)

==Identification==

A fully general [[Single-access key|dichotomous key]] requires a mature, flowering plant.<ref name="FNA 133668" />{{sfnp|Case|Case|1997|pp=71-85}}{{sfnp|Barksdale|1938|pp=278-279}}{{sfnp|Freeman|1975|pp=4-6}} The first step is to determine whether or not the flower sits on a [[Pedicel (botany)|pedicel]], which determines the subgenus. (Any mature plant may be identified to this extent, even if it is not in bloom.) Identification proceeds based on flower parts, leaves, and other characteristics. A combination of characteristics is usually required to identify the plant.

Identification of a non-flowering, non-fruiting plant with bare leaves may be difficult. Although some species of ''Trillium'' have [[Petiole (botany)|petioles]] (leaf stalks) and/or distinctive leaf shapes, these features are seldom sufficient to identify the plant down to the species level.

In eastern North America, jack-in-the-pulpit (''[[Arisaema triphyllum]]'') is often mistaken for bare-leaved ''Trillium''. Both species are about the same height with [[Glossary of leaf morphology#trifoliate|trifoliate]] leaves but the former lacks 3-way rotational symmetry and has leaf veins unlike those of ''Trillium''.