Mustard White | The Natural Web

There is a time during early spring when woodland understory plants carpet the forest floor. These plants emerge from the ground through a covering of fallen leaves, and before the tree canopy above them finishes leafing out, they bloom, develop fruit, disperse their seeds, and their visible parts die back. They spend the rest of the year storing energy in their underground root systems, waiting for their window for photosynthesis the following spring. These plants are the spring ephemerals, a term that reflects the brevity of their appearance above ground.

Trout Lily (Erythronium americanum), Virginia Bluebells (Mertensia virginiana), and Mayapple (Podophyllum peltatum)

Spring ephemerals support an entire ecosystem of animals that depend on them for their continued existence. Some of those animals are also ephemeral in nature, active and visible to us humans for the same time period during which the plants on which they depend are active.

Spring Beauty (Claytonia virginica), Trout Lily or Dogtooth Violet (Erythronium americanum), and Dutchman’s Breeches (Dicentra cucullaria) are just a few of the spring ephemerals. They all provide food for a variety of pollinators, primarily native bees and flies who are active during the brief time these flowers are blooming. Bees and flies visit flowers for both nectar and pollen, essential food for themselves, and in the case of bees, also for their larvae.

Spring Beauty (Claytonia virginica)

Trout Lily or Dogtooth Violet (Erythronium americanum)

Spring Beauty and Trout Lily host mining bee species that specialize on their pollen. Just as Monarch butterfly caterpillars can only eat the leaves of Milkweeds (Asclepias species) to survive, these bees can’t digest the pollen of any other plants. Without these plants, we wouldn’t have the bees. In turn the bees are very efficient pollinators for the plant species on which they specialize. About twenty-five percent of our native bees are specialists on a small group of related plants.

Spring Beauty (Claytonia virginica) with mining bee

Trout Lily or Dogtooth Violet (Erythronium americanum) with mining bee, probably the specialist Andrena erythronii

In addition to bees and flies, Spring Beauty’s shallow bowl-like flower shape also accommodates dining for spring flying butterflies.

Juvenal’s Duskywing drinking nectar from Spring Beauty (Claytonia virginica)

Dutchman’s Breeches’ primary pollinators are queen Bumble Bees, newly emerged from their winter shelters.

Queen Bumble Bee pollinating Dutchman’s Breeches (Dicentra cucullaria)

Some native Mustard (Brassicaceae) family members are spring ephemerals, including Cut-leaved Toothwort (Cardamine concatenata), Toothwort or Crinkleroot (Cardamine diphylla), and Smooth Rockcress (Arabis laevigata). The flowers of Mustard family members have four petals arranged in a cross shape, often forming a tube at the base of the flower.

Cut-leaved Toothwort (Cardamine concatenata)

Toothwort or Crinkleroot (Cardamine diphylla)

Smooth Rockcress (Arabis laevigata)

Not only do these plants provide nectar and pollen for early flying bees and flies,

Cut-leaved Toothwort (Cardamine concatenata) with bee

but they are also food plants for the caterpillars of some butterflies in a group called the Whites. Where I live in New Jersey, Cut-leaved Toothwort and Smooth Rockcress host a member of this group called the Falcate Orangetip. At rest they are unmistakable, with a gray and white marbled pattern on their ventral (under) side, the males with the distinctive orange wing tips above. They are very flitty, though, so it’s hard to get a good look, or a photo!

Falcate Orangetip drinking nectar from Spring Beauty (Claytonia virginica)

It was only a year ago that I first spotted this butterfly, on a woodland trail where Cut-leaved Toothwort and Smooth Rockcress are both present.

In the northern tier of the eastern United States and in parts of Canada, the Mustard White butterfly uses some of these same Mustard family members as its required caterpillar food. The West Virginia White, a fairly uncommon butterfly’, uses both Toothwort species.

Mustard White drinking nectar from Bluets (Houstonia caerulea)

In flight both the Falcate Orangetip and Mustard White can easily be mistaken for the very common, non-native Cabbage White, so in spring it’s worth taking a careful look at any small white butterfly you see in a woodland area where these native mustard family members are present. The butterflies’ active period mirrors that of their caterpillar food plants, so you can only see them for about 4-6 weeks during the spring.

Cabbage White

Without our native Mustard family members, the Falcate Orangetip and Mustard White and West Virginia White butterflies would cease to exist.

There is a whole ecosystem of species interdependent with native spring ephemerals that can only be observed during the fleeting weeks of early spring. This is just a tiny window into that world. For more on the spring ephemeral ecosystem, see the posts listed below. Even better, go outside and experience it for yourself!