Trillium

Take a walk in any woodland at this time of year and there is a multitude of wildflowers growing on the forest floor.  The genus trillium, in the lily family, includes forty-three species worldwide and thirty-eight that can be found in North America, most east of the Mississippi River.

Trillium flowers come in a variety of colors including white, yellow, pink, red, purple, and striped.  When mature, all parts of the plant are in multiples of three including bracts, sepals, petals, anthers and ovules.  All species are herbs that grow from seed or by sending out roots to start new plants.  In biological terms, there are no true leaves nor stalks.  Only the flower and bracts, usually identified as leaves, are visible aboveground, existing as extensions of the root.  The bracts do function like leaves including photosynthesizing food for the plant.

Prairie trillium, Trillium recurvatum, likes wet or dry woodlands and savannas.   Flowers are at the ends of 6″-15″ tall stems surrounded by three green bracts.  The flower has three triangular, dark maroon sepals containing six stamens with black anthers.  A single fruit develops with several small, dark brown seeds.  Variations of this plant have been found with yellow petals and purple anthers.

Toad trillium, Trillium sessile, is found in the southern portion of DuPage County and further south in Illinois.  Growing on bluffs and banks of streams and rivers, it is uncommon in dry woodlands.  Sessile flowers, a term referring to a flower developing directly on top of the bracts, are dark maroon containing six maroon and yellow-striped anthers.  Ovules develop into a three-celled white to purplish-green fruit with several seeds in each cell.

Large-flowered trillium, Trillium grandiflorum, has become less common over the last few decades.  It is found in wet or dry woodlands and savannas.  8″-18″ tall, it produces a single flower 2″-4″ across composed of three white petals set against three green sepals.  The flowers slowly turn pink as they age.  Possibly due to the more showy appearance, this plant is readily browsed by deer.  When found in colonies, the large leaves can form shelter for small mammals such as field mice and shrews.

Declined Trillium, Trillium flexipes, is found in wet or dry woodlands, particularly in oak dominated areas.  Growing up to 2′ tall, a single white flower is produced on a nodding peduncle of a mature plant.  About 2″ across, the flower is three white petals and three green sepals surrounding six light yellow anthers.  The flower hangs downward a little above or below the bracts.  A six-angled seed capsule replaces the flower in late summer.

Trilliums develop very slowly, often taking several years to develop into a mature plant able to produce flowers and seeds.  During summer heat and drought, plants may go dormant, retreating back into the thick root.  Because of this slow growth rate, trilliums are not often found in nursery sales.  Each year as a new shoot is sent up from the root, a ridge forms where the new bud grows.  Counting the ridges on a root can give a good indication of the age of the plant.  Many plants have been found that are several decades old.

Trilliums spread by seeds that contain an elaiosome, a white, fleshy container of nutrients attached to each seed.  Favored by ants and wasps, this nutritional package is taken to feed their young while the seed is ignored.  Ants nesting in soil mounds or decomposing wood and yellow-jacket wasps nesting underground all help to move seeds around.

Spring is lasting a little longer this year with the cooler temperatures we have been experiencing.  I hope you get out for a woodland walk to see the many wildflowers in bloom.