Butterfly invasion

In the Garden

Ralph Purkhiser, Purdue University Master Gardener

     Just as the buzz of cicadas has ceased, another invasion seems to be in effect at Sandhill Gardens.  This one is actually very enjoyable.  When walking through the gardens, I am surrounded by butterflies!  This is no accident.  I love these flying flowers and have included many butterfly-friendly plants in my garden beds, with the aim of attracting and sustaining butterfly populations.

     When it comes to butterflies, there are two distinct types of plants.  Most butterflies have a specific host plant on which they lay their eggs.  The host plant is the food for the larvae, who begin to eat as soon as the eggs hatch.  Growing host plants takes a tough gardener.  You have to be willing to look at plants on which the leaves have been skeletonized.  I personally smile when I see the lacy-looking leaves on certain plants, because I know they have fulfilled their purpose.

     Nectar for the adult butterflies is the other plant need.  Nectar comes from flowers, and butterflies are especially fond of flowers that grow in clusters, allowing them to eat from several blooms without having to move for a while. 

     Some plants can perform both functions.  Perhaps the most famous dual-purpose butterfly plant is milkweed.  It is well-known as the host plant for monarch butterflies and the blooms are nectar-rich and provide food for monarchs and many other butterfly species.  Considered a weed by many, in recent years, gardeners and conservationists have mounted a campaign to increase milkweed cultivation.  The Latin name for milkweed is Asclepias, named for the Greek god of healing.  Indeed, various milkweeds have been used medicinally for centuries.  Some have even been used for food, but all have at least some degree of toxicity.  This toxicity is important for the monarchs.  The toxic substances stay in the butterfly’s body and keep it safe from preditors.

     Worldwide, there are more than 200 individual species in the genus Asclepias, occurring mostly in North and South America and Africa.  In Indiana, at least 15 species occur perennially and one may grow other tropical species as annuals.

     At Sandhill Gardens, three species of Asclepias are found growing in the meadow and other wild areas.  The most common is simply known as common milkweed or Asclepias syriaca.  These plants may top five feet tall and the flowers grow in ball-like clusters.  The flowers are a dark mauve color and are almost always covered with many different types of butterflies.  One of the showiest milkweeds is Asclepias tuberosa or butterfly weed.  The bright orange and yellow flowers occur in flat umbrels on plants that rarely top two feet tall.  Swamp milkweed (Asclepias incarnata) grows in areas with moist soil.  It has thick, white running roots that allow the plant to form colonies and survive in heavy clay soils.  The flowers are in clusters about two inches across and are white to light pink and are sometimes mistaken for Queen Ann’s lace or poison hemlock.

     The other milkweed species found in Indiana have specific cultivation needs and many are found in only limited places.  Aquatic milkweed (Asclepias perennis), as one might expect, requires consistently wet soil.  It will have white ball-shaped bloom clusters.  Clasping milkweed (Asclepias amplexicaulis), also known as sand milkweed and curly milkweed, grows only in dry, sandy soil and its pink flowers grow in loose umbrels, resembling pom-poms.  Mead’s milkweed (A. meadii) is a rare milkweed, found in only 6 midwestern states.  In fact, it once was extinct in Indiana, but has been re-established from plants found in Illinois.

     Other Hoosier milkweeds include fourleaf milkweed (A. quadrifolia), green antelope horn (A. viridis), green comet (A. viridiflora), poke milkweed (A. exalta), prairie milkweed (A. sullivantii), purple milkweed (A. purpurascens), redring milkweed (A. variegata), tall green milkweed (A. hirtella), and whorled milkweed (A. verticillata).  Some are quite rare and are considered threatened due to habitat loss.  The milkweeds really are not a weed at all, but essential plants to the cycle of life for monarchs and other butterflies.