Great white trillium

Appearance

"T. grandiflorum" is a perennial that grows from a short rhizome and produces a single, showy white flower atop a whorl of three leaves. These leaves are ovate in outline with pointed tips. They lack petioles and measure 12–20 cm long by 8–15 cm wide, with very prominently engraved venation.

The leaves and the stem share a dark green color and persist into autumn. Leaves and petals both have somewhat undulate margins, the leaves often much more strongly so. Individuals grow to between about 15 and 30 cm tall. A single rootstock will often form clonal colonies, which can become very large and dense.

The erect, odorless flowers are large, especially compared to other species of "Trillium", with 4 to 7 cm long petals, depending on age and vigor. The petals are shaped much like the leaves and curve outward. They have a visible venation, though this is nowhere near as marked as on the leaves.

Their overlapping bases and curve give the flower a distinctive funnel shape. Between the veined petals, three acuminate sepals are visible; they are usually a paler shade of green than the leaves, and are sometimes streaked with maroon. Flowers are perched on a pedicel raising them above the leaf whorl, and grow pinker as they age.

Flowers have six stamens in two whorls of three, which persist after fruiting. The styles are white and very short compared to the 9–27 mm anthers, which are pale yellow but becomes a brighter shade when liberating pollen due to the latter's color. The ovary is six-sided with 3 greenish-white stigmas that are at first weakly attached, but fuse higher up. The fruit is a green, mealy and moist orb, and is vaguely six-sided like the ovary.

Status

Some forms of the species have pink instead of white petals, while others with extra petals, also called "double" forms, are naturally quite common in the species, and these are especially popular with trillium gardeners.

In fact, the species is the most popular of its genus in cultivation, which has led to conservation concerns due to the majority of commercially available plants being collected from the wild. A few regional governments in Canada and the United States have declared the plant vulnerable as a result.

Habitat

"T. grandiflorum" favors well-drained, neutral to slightly acid soils, usually in second- or young-growth forests. In the Northern parts of its range it shows an affinity for maple or beech forests, but has also been known to spread into nearby open areas.

Depending on geographical factors, it flowers from late April to early June, just after "T. erectum". Like many forest perennials, "T. grandiflorum" is a slow growing plant. Its seeds require double dormancy, meaning they normally take at least two years to fully germinate. Like most species of "Trillium", flowering age is determined largely by the surface of the leaf and volume of the rhizome the plant has reached instead of age alone.

Because growth is very slow in nature, "T. grandiflorum" typically requires seven to ten years in optimal conditions to reach flowering size, which corresponds to a minimum of 36 cm2 of leaf surface area and 2.5 cm3 of rhizome volume. In cultivation, however, wide disparity of flowering ages are observed.