Trillium luteum

Trillium luteum, also known as the yellow wood trillium, is part of a group of small wild plants native to North America, quite rare in cultivation, that undoubtedly deserve to be tried in the shaded and damp areas of our gardens. Simple and graceful, the luteum species, as its Latin name suggests, has yellow flowers. Nestled in the heart of a bouquet of grey-silver maculated leaves, a narrow and erect flower is born in spring, whose colour and fragrance pleasantly evoke those of lemon. A bit slow to establish, this trillium spreads through its rhizome, ultimately forming an unusual spring carpet in a wooded garden or a shady rockery.

Trillium luteum, long classified in the Liliaceae family, now belongs to the Melanthiaceae family. It is a distant North American relative of fragrant Solomon's Seal that populates our European woodlands. It originates from the southeastern United States (North and South Carolina, Tennessee, southern Kentucky, and northern Georgia), where it flowers in spring in the humus of deciduous woodlands but also on rocky banks, often not far from watercourses, on mainly limestone substrates.

Trilliums are very peculiar plants that do not develop true stems or true leaves. The vegetation that emerges in spring is actually just a flowering, composed of an upright petiole, an extension of the rhizome, bearing a coloured flower that surmounts bracts resembling leaves. The true leaves, tiny and scale-like, are found on the flower's petiole. 

A herbaceous and perennial plant, Trillium luteum develops in spring from a fleshy and thick underground rhizome that does not like to be disturbed. It goes dormant as soon as the soil dries out, in the course of summer, or in autumn due to the cold. The plant produces short and slender leafy stems, standing 30-40 cm (12-16in) above the ground. Thanks to its rhizomes, this Trillium will eventually slowly form small colonies occupying at least 30 cm (12in) of ground. Each stem carries 3 beautiful leaves inserted at the same level on the stem and arranged horizontally. The leaves are round to lanceolate in shape, a beautiful bright green randomly marbled with grey and silver, especially when young. They measure about 12 cm (5in) long and 10 cm (4in) wide. The flowering takes place in April-May, more or less early depending on the climate, in the centre of the trio of leaves. The flower, erect, narrow and 4-5 cm (2in) tall, is composed of 3 slightly twisted bright yellow petals surmounting 3 narrow green sepals arranged in a staggered fashion. This strongly lemon-scented flowering attracts various pollinating insects. This species is very difficult to multiply by sowing. In Trilliums, seeds are dispersed by ants. Plants from seeds may take several years before flowering. 

A bit slow to establish, this Trillium luteum is long-lived, and requires little care where it is happy. It should be planted in groups of 3 specimens in woodlands or dappled sunlight (introduce several plants in a small area), in soil rich in humus or leaf compost that remains moist for as long as possible. It pairs well with other small perennials that enjoy the same environments, such as Mertensia virginica, with its springtime blue flowers. Plant flowering plants or interesting foliage that will fill the ground in summer, while the trillium rests underground: consider Ophiopogons, Saxifraga, small ferns, Asarum, hostas, etc. It can be grown in pots, with careful watering. In the ground or in pots, it always makes a successful pairing with Begonia grandis subsp. evansiana, which takes over its flowering.

The Latin name Trillium derives from the fact that the different parts of these plants are ternary: from the unique cluster of three leaves on each stem, to the construction of the flower, composed of 3 green sepals, 3 colored petals, six stamens, and 3 fused carpels.