In the Garden
Ralph Purkhiser, Purdue University Master Gardener
What are those yellow, daisy-shaped flowers growing along the roads? This question has been posed to me many times, and there are many answers. There are actually several different genera, each with multiple species that may have daisy-like yellow flowers. Some are natives, and others were introduced and have naturalized. The question of native or introduced sometimes gets pretty muddied. Many native flowers were collected by early explorers and taken to Europe. Some were bred to form new cultivars, which eventually made their way back to Indiana, where they escaped from cultivation. These Nativars (cultivars of native plants) sometimes tend to out-compete the original species. Sometimes the native plants cross with the introduce plants, producing hybrids. Even the experts argue if these plants are considered native or invasive.
The easy answer to the question above would be to call all of them black-eyed Susans. Indeed, that common name is often applied to such flowers, but is usually reserved for plants in the genus Rudbeckia, and most often to the particular species Rudbeckia hirta. This common plant is a good example of a plant that has been the focus of breeding efforts, with several cultivars now existing. It becomes difficult to determine the exact cultivar existing in a wild setting. Rudbeckia fulgida is also native, but is rare in Indiana, and some varieties are considered endangered.
The genus Helianthus is also common along Hoosier roadways. There are many species, and this genus has long been the subject of breeding efforts to produce the sunflowers that provide food, oil and other products, and also to provide the many garden sunflowers popular as annual plants in flower beds. We often see bees and other pollinators visiting plants of this genus, and their efforts result in many crosses. The seeds drop or are carried by animals, resulting in many stands of sunflowers. One particular native species that is presently in bloom is Helianthus tuberosa—the Jerusalem artichoke. They have been called the intersection of flowers, food and foraging. That common name is a big misnomer. The species has nothing to do with Jerusalem and they are only very distantly related to the artichoke. However, the tubers have been cultivated as a food crop for centuries by native peoples. They were one of the earliest plants taken by explorers back to Europe, where they became popular for food and livestock feed. In fact, the tuber was dubbed the greatest soup vegetable at a French food festival. The tubers fell out of favor as a vegetable for many years, but have been making somewhat of a comeback. They may be eaten cooked, raw or pickled, and are often touted as a low-carb alternative to potatoes. They will propagate from seed or will re-grow from pieces of the tubers, so they often form dense colonies that are aggressive and will choke out competition.
While there are numerous species of sunflowers, some of the similar-looking flowers belong to the genus Heliopsis. This genus is commonly known as false sunflower.
The genus Silphium includes several species. Prairie dock, cup plant, compass plant and various rosinweeds are included in this genus. Most of them are tall plants with the flowers towering above some of the plant world’s most interesting foliage. Many of the species are more common in marsh areas of northern Indiana, but the cup plant is common here in the south. The leaves actually form cups along the stem, where rain may be caught and will persist for some time. This plant is one that seems to attract the attention of visitors to my meadow.
Other genera producing yellow daisies include Coreopsis, Helenium, Verbesina and Ratiba. Many of these also exist in the meadow at Sandhill Gardens. Come to the garden open house on September 28 to have a look at some of these plants.