Know Your Native Wildflowers: Trillium


Think about numbers in nature for a second.  Most animals have two ears, four legs. A dogwood blossom has four petals, while the eastern spring beauty has five petals.  The brilliant orange tiger lily has six petals, and starflowers have seven pointed white petals.

One flower that our region’s warm spring weather has caused to bloom a bit earlier than usual has three petals – and has an appropriate name to boot.


Trillium grow in abundance in Pittsburgh's parks. One of the brightest that you can see right now, Trillium grandiflorum, has three brilliant white petals that form a single flower.  This bloom rises from three large green bracts that sprout out from the thin stem.  These bracts (leaves) are photosynthetic, gathering light energy from the sun and turning it into chemical energy that allows the plant to grow.  This is a very popular plant for gardeners, however most white trillium is collected from the wild.  This has led to it being listed as threatened in New York, and endangered in Maine.  

The bright white petals and lush greenery of the trillium is one of it’s most identifiable characteristics, but it’s best to identify this flower by the number of petals, as there can be wide variances in color. While most trilliums in our region are white, with a careful eye you may spot petals that are pale green, red, purple, or yellow.  You may even spot trilliums that are a combination of these colors, such as white petals with purple or burgundy stripes, white petals with green stripes, or yellow petals with pale emerald stripes.


Another trillium commonly found in Pittsburgh's parks is the deep scarlet Trillium sessile, commonly referred to as toadshade.  This type of trillium is also has three leaves, but the leaves are very broad and have are mottled light and dark green.  Even in full bloom, the bloom looks kind of closed and smells like rotten meat.  This also attracts flies and beetles that help to pollinate the flowers. 

Most of the time trilliums spread through their rhizomes (root-like structures) underground.  This produces patches where all of the plants are nearly all genetically identical.  For seed dispersal, trilliums are myrmecochorous -- they're spread by ants!  Each seed has a little bit of fat attached to it called an elaiosome.  Ants carry the elaiosome – with the seed attached - back to their colonies, where they'rei nadvertently planted. 

Trilliums are native to the United States in all but a handful of southwestern states, and you will often see blankets of them that cover large expanses of the forest floor in Frick, Highland, Riverview, and Schenley Parks.  Trilliums love soil that is rich in organic matter and holds moisture well, so the woodland floor – with it’s decaying branches and leaves – is the perfect home. The soil composition affects the way trilliums grow and taste, which is important to the effect that one of this spring wildflower’s biggest fans may have on its chance to flourish.  Deer know that trilliums are a tender, water-intensive plant, but the degree to which they will devour them depends on their taste. That is why some areas of our parks may have lots of untouched trilliums, while others will show signs that deer have been grazing on their beautiful blooms.

- Scott Roller and Mike Cornell for the Pittsburgh Parks Conservancy