Cup Plant

Silphium perfoliatum

Description & Overview

Attractive to us and attractive to wildlife; Cup Plant fosters a habitat with a native ecosystem and works in conjunction with the environment to create a full perennial hedge. The beautiful, large-yellow flowers look similar to a Sunflower or a large, yellow Aster, and bloom in the hottest months of the summer (July-September). At the peak of the season, this native Wisconsin flower can create privacy with its large size, which is uncommon for perennials. This maintenance-free plant will also make the perfect addition to a rain garden!

Core Characteristics

Suggested Uses:

Cup Plant is a wonderful addition to any prairie, woods, bank, or butterfly garden. Reaching upwards of 8′ tall, it is a dominant vertical accent to any area. The blooms will open in July and persist into September when the colder nights encourage the plant to seed. Cup Plant needs full sun and is easily propagated by seed collected in late September and October. Tolerant of wet conditions, it’s a perfect match for a rain garden or wet site. Growing tall, Cup Plant can over-crowd a smaller perennial garden. A central taproot will hold the large stalk steady while it spreads by shallow rhizomes to reproduce vegetatively.

The name “cup plant” comes from the physical characteristic the plant has with its’ middle leaves. If you look closely, you’ll see that there are no petioles and that the opposite leaves are attached to form a cup. This cup catches rainwater and is used by insects and birds for water and nesting.

Wildlife Value:

Cup Plant flowers provide a wonderful feast for native bees and provides a balanced structure and materials for bees to nest. Water caught in the cup-like leaves acts like a birdbath while the large seed heads provide food to birds.

Cup Plant attracts hummingbirds, monarchs, skippers, moths, and a diversity of bees, wasps, and bee flies. It is the host plant for the Silphium moth (Tabenna silphiella) and Giant Eucosma moth (Eucosma giganteana). Variegated Fritillary (Euptoieta claudia), Fiery Skipper (Hylephila phyleus), and Eastern Tiger Swallowtail butterflies (Papilio glaucus) visit seeking nectar. Cuckoo bees (Triepeolus spp.), Green Sweat bees (Agapostemon spp.), Long-horned bees (Melissodes spp.), Bumblebees (Bombus spp.), Leafcutter bees (Megachile spp.), and Mining bees (Andrena spp.) will stay busy drinking nectar from the flowers.

Katydids feed on the leaves and large populations of aphids may reside on the underside of leaves. This is great news for Ladybug larvae and Brown Lacewing larvae as they are both predators of aphids.

Gold Finches are known to drink water from the cups and take shelter in the dense stems.

Maintenance Tips:

Cup Plant is a maintenance-free, easy grower. You’ll know your cup plant has been successfully established in your landscape once it begins to produce seed. This may take a year or two; however, it will flourish after it’s established. Stems can be cut back to the ground if the plant is encroaching other areas. Be sure to only prune a couple of stalks in a growing season because creating a wound can leave any plant vulnerable to infection. If in a drought, it may drop lower leaves until vigor can be returned to the upper leaves and flowers. Brown buds or leaves, stunted growth, and aborted blossoms are indications of stress. Again, it’s a maintenance-free plant, so first consider whether or not external factors (light, water, soil, etc.) are meeting this plant’s needs.

Pests/Problems:

Cup Plant doesn’t have any major pests or diseases. Native wildlife, such as the Gall Wasp will feed within the stems of the leaves. This can attract a parasitic wasp; however, this process will not affect the health of the plant.

Since it’s a tall, leggy plant, strong winds may cause it to fall over, this can also occur from the weight of the blooms. This is a normal characteristic of the plant and can either be left alone, or you can stake the plant.

Leaf Lore:

The genus name Silphium comes from the Greek word for ‘Silphion’ a plant also known as ‘laserwort’ or ‘laser.’ The resin exuded from the stems of this genus was once made into chewing gum to prevent nausea and vomiting. The specific epithet perfoliatum is said to be translated to “leaf surrounding or embracing the stem.” This family of plants was found by Carl Linnaeus, an 18th century Swedish Botanist and the developer of the binomial nomenclature of modern taxonomy.

Companion Plants:

Cup Plant is a great plant for a large, wetland garden, and can be paired with other tall natives, like Ironweed, Spotted Joe-Pye Weed, Meadow Rue, Spiderwort, Wild Quinine. Combine with shrubs like Gray Dogwood or trees like Black Cherry to really befriend all the birds. Some smaller perennials that would look great in front of the Cup Plant include Wild Bergamot, Wild Geranium, Prairie Smoke, Anise-Hyssop, and many more. Cup Plant makes a great backdrop for a perennial garden or an integral piece of a wetland hedge.

CUP PLANT BENCHCARD