Trillium ovatum

Trillium ovatum, the Pacific trillium, also known as the western wakerobin, western white trillium, or western trillium, is a species of flowering plant in the family Melanthiaceae. It is found in western North America, from southern British Columbia and the tip of southwestern Alberta to central California, east to Idaho and western Montana. There is an isolated population in northern Colorado and southern Wyoming.
"T. ovatum" is the most widespread and abundant trillium in western North America. It is the only pedicellate-flowered "Trillium" species found within its range. The type specimen for this species was gathered by Meriwether Lewis in 1806 along the Columbia River during the return trip of the Lewis and Clark Expedition.
Taxonomy.
In addition to "Trillium ovatum" , the following infraspecific taxa are accepted:
The form "T. o." f. "hibbersonii", sometimes called the dwarf trillium (not to be confused with "T. pusillum"), is a mere tall. Unlike the nominate variety "T. o." var. "ovatum", the flower petals open pink but fade to white as they age. The form "hibbersonii" is found primarily on Vancouver Island in British Columbia but occurs occasionally throughout the range of the species.
The variety "T. o." var. "oettingeri" is endemic to the Salmon Mountains of northwestern California and hence Oettinger's trillium is known as the Salmon Mountains wakerobin. Unlike the nominate variety "T. o." var. "ovatum", the variety "oettingeri" has leaves with short petioles and linear flower petals.
Numerous synonyms are in use. For instance, the synonym "Trillium ovatum" f. "maculosum" refers to a form with mottled leaves that occurs in Mendocino County, California. This is the only reported instance of mottled leaves in a pedicellate "Trillium".
Description.
The most widespread of the western North American trilliums, "Trillium ovatum" varies greatly within its range. Despite this, "T. ovatum" closely resembles the eastern "T. grandiflorum". Apart from geographic location, the two species are not easily distinguished.
"T. ovatum" is a perennial herbaceous plant that spreads by means of underground rhizomes. At maturity, each plant has one or two flowering scapes, each in length. The specific epithet ovatum means “egg-shaped,” which refers to the petals, not the leaves. The latter are generally ovate-rhombic, long by wide.
The flower sits on a pedicel in length. The sepals are long and wide, while the petals are long and wide. Typically the flower opens white and becomes pink with age, but in the Smith River Canyon area of northern California and southern Oregon, the petals become almost barn-red.
Habitat and ecology.
"Trillium ovatum" is often found growing in coniferous and mixed coniferous-deciduous forests, in and around alder thickets and shrubs. Along the California coast, it is commonly found under coast redwood and mixed evergreen forest. At Lolo Pass, Montana, it grows under spruce and Douglas fir in ravines along mountain streams.
Flowers bloom late February in the southern part of its range, and in March or April elsewhere. Citizen science observations of flowering plants of this species peak during the first week of April. For comparison, when "Trillium grandiflorum" is fully open in eastern North America, "T. ovatum" is already fading in western North America. Apparently "T. ovatum" lacks sufficient winter hardiness to flourish east of the continental divide.
The life-cycle stages of "T. ovatum" include a cotyledon stage, a one-leaf vegetative stage, a three-leaf vegetative (juvenile) stage, a three-leaf reproductive (flowering) stage, and a three-leaf nonflowering regressive stage. An example of the latter involves a transition from the three-leaf flowering stage to a three-leaf nonflowering regressive stage. Approximately one of every four reproductive plants regresses to a nonflowering state in any given year. Under the right conditions, individuals may undergo extended dormancy, that is, they may cease above-ground growth for one or more years. In western Montana, dormancy was observed in all adult stage classes, with most plants returning to above ground status in a year or two, although some plants exhibited dormancy for 3–5 years.