Silphium integrifolium–the name doesn’t seem to do the flower justice. Silphium is a standout plant for many reasons. It blooms in sun and shade. There are many flowers on each plant. It’s one of the few plants that blooms all summer and into fall. As a bonus, the large sunflower-like flowers attract butterflies, hummingbirds, yellow finches, bees and all kinds of interesting insects. If that is not enough, it is drought tolerant. She managed to open at least some of her flowers in the heat and drought of summer 2012. For all of these reasons, she is in my top 10 wildflower list.
Latin Name/Common Name- The genus name, Silphium, has a Greek origin and refers to the resinous juice that can be seen when the stem of a Silphium plant is injured or broken. The species name, integrifolium, refers to the “entire or uncut leaves”. The common name, Rosinweed comes from the resin produced during blooming. This was used similar to chewing gum by some Native Americans. I haven’t tried it–maybe next year.
Description- With a height of 3-5 feet, Silphium integrifolium is the shortest of the towering Silphium family. She has a stout central stem that has a fuzzy appearance due to being covered with stiff hairs. The stem color varies depending on sunlight. Plants growing in shade have green stems. Plants growing in a sunny meadow often have pretty reddish stems that contrast beautifully with the large green leaves. The plant grows from a single stem that branches near the top to support numerous flower heads.
Green stem in shade and Red stem in sun
Each set of leaves is rotated in direction 90 degrees as they ascend the stem. You can appreciate this in the picture above.
The leaves are opposite and sessile (lack petioles). The shape is lanceolate or ovate. Leaf margins vary from smooth to lightly toothed.
Leaves may have smooth (left) or toothed (right) margins
The leaves are covered top and bottom with stiff hairs. This gives them a sandpapery, rough texture and they cannot be rubbed.
Flowers appear at the top of the plant. Each flower is about 2 -3 inches across. I’ve noticed the flowers are smaller in years of drought. The flower is composite, meaning it has both ray florets and disk florets. Typically, the ray florets number about 12-25. Each has a single notch at the tip.
Note the tiny notch at the tip of each ray flower
Bloom Time- The long bloom time is just one of the wonderful attributes of this lovely plant. On Ozarkedge, I’ve seen it in bloom from early July through mid October.
Early flower bud, slightly open bud and spent blossom
Habitat- Growing well in both full sun and shade,Silphium integrifolium is not a picky plant. It is seen in prairies, limestone glades and at the edges of rocky forests. It is one of our most drought tolerant plants. I’ve noticed in extreme drought, some buds will turn black and drop in order to preserve others for blooming.
Woodland and prairie habitat
Buds often turn black and drop in severe drought
What’s Growing Nearby?There are many plants growing nearby depending on the habitat. In the woodland habitat, I find Silphium integrifolium close to Coreopsis tripteris, Coreopsis grandiflora, Rudbeckia submentosa and Cirsium altissimum. In the sunny habitat, I often see Euphorbia corrolata, Strophostyles umbellata, Rudbeckia hirta and Pycnanthemum tenufolium.
Coreopsis tripteris Coreopsis grandiflora Rudbeckia submentosa
Euphorbia corollata Strophostyles umbellata Pycnanthemum tenufolium
Endangered List- Silphium integrifolium is listed on the USDA Plants Database as Threatened in Michigan- http://plants.usda.gov/java/profile?symbol=SIIN2. This picture shows the distribution in Arkansas based on the USDA website. I suspect the distribution may be greater than shown in northeast Arkansas.
Interesting Tidbits- Many insects, bees, butterflies and birds are attracted to the lovely flowers and seeds of Silphium integrifolium. Take a look at a few below.
Praying mantis and grasshopper