Summer Silphiums

When you think of dependable summer flowers, does Silphium come to mind? The bright yellow flowers of this adaptable genus should be in every Georgia garden, yet not many people know about them. Rudbeckia and Helianthus, “cousins” in the Asteraceae family, are widely cultivated for their summer blooms. In fact some people assume that any Silphium they find in the wild is a sunflower (a common name for Helianthus).  Silphium deserves more use and recognition for its own merits.

Cup plant (Silphium perfoliatum)

Rosinweed is not a name to attract your attention when looking for new choices for your landscape. It sounds both sticky and weedy. It apparently does contain a resin that was used by Native Americans but I have never encountered it with ordinary gardening practices. While rosinweed is the common name for the genus as a whole, individual species have more appealing names like cup plant (Silphium perfoliatum, S. connatum) and compass plant (S. laciniatum not native to Georgia).

Native only to North American, several of these robust plants are prairie species, adapted to tough conditions. A fair number are found in the southeastern US and 10 of the 19 species are found in Georgia. I have grown 3 of them in my garden and I highly recommend them all. I will mention that in my deer-infested area, deer do browse the young leaves (and apparently cattle will do so as well if you have any of those).

 

Starry rosinweed (Silphium asteriscus)

 

Starry rosinweed (Silphium asteriscus) was the first one I planted. I was skeptical of its coarse appearance. There is a bonus to its rough leaves – the deer bother this one the least of the three. It starts blooming in June and continues through August, just one or two at time, but always a bloom. By the time it is done, the earliest flowers have already developed mature seed and the goldfinches are after them.

My second species in the garden looks like different from the first. Thick, glossary basal leaves anchor the plant while the flower stalk shoots for the sky where it explodes into a spray of small flowers. If I could grow kidney-leaf rosinweed (Silphium compositum) only for those scalloped leaves, I would still have it. The flowers last for a few weeks and then … again with the songbirds looking for seeds.

Kidney-leaf rosinweed (Silphium compositum)

Cup plant (Silphium perfoliatum, synonym S. connatum) is the third plant that I have grown. It was given to me by my friend Mary. It struggled for a few years, plagued by roaming deer. Once I expanded my fence, it happily shot up to about 7 feet tall. It started blooming in late June and looks set to continue well into August. 

Cup plant (Silphium perfoliatum, synonym S. connatum)

The plant gets its common name from the cup that is formed where the stem pierces the leaves. Rainwater can collect in the cup, providing a reservoir for insects and small birds.

Flowers are popular with pollinators. Mine has hosted a number of different bees. Several posts at Beautiful Wildlife Garden show an array of butterflies on the authors’ cup plants. 

The taller species of Silphium have a habit of turning their flowers to follow the sun. As I mentioned, one species has the common name compass plant, but it really could apply to several. To be helpful to the insects that help you with pollination, leave the thick stems of Silphium standing to provide a winter home for those that spend the winter inside plant stems.

So keep a look out for these beauties in the future. If you find some in the wild and aren’t sure if what you found is a Silphium, just check the back of the flower and look for the 4 green bracts. My earlier post about identifying summer yellow flowers has some pictures to help you with that.

Black seeds in the seedhead waiting for a bird to come along

I hope you are now encouraged to add one of these great plants to your garden. The Georgia Native Plant Society has sufficiently enthused (about this plant) propagators such that we usually have some at our plant sales. They start very easily from seed.

 

Caterpillars Are Life

Caterpillars are not icky worms with legs that poop on your sidewalk. [Well, they do poop on your sidewalk but think of that as free fertilizer as you sweep it into the adjacent flower bed.]

American lady caterpillar on Antennaria

Caterpillars are life – life for beautiful flying creatures as their larval form ... and all that depend on them.

After a recent talk at the Cullowhee Native Plant Conference about caterpillars, I am energized and prepared to identify and appreciate more caterpillars than ever.

Background: As most of you know, caterpillars are the larval form of butterflies and moths (Lepidoptera). Local insects like Lepidoptera have evolved over time with their local ecosystem and the relationships they have with organisms like plants are both necessary and complex.

David Wagner from the University of Connecticut presented his topic “Native Plants, Caterpillars, Birds – A Story of Connected Fates” on Friday morning to the main group. David is author of “Caterpillars of Eastern North America,” now in its 8th printing since 2005.

His talk was lively and informative, a reflection of his keen interest in and knowledge of caterpillars. Some of the things I learned:

• Specialization on certain plants matters. 80% of Lepidoptera are specialists, eating just one or within a small set of host plants. Some specialize on just a part of the plant! As a result, changes in populations of a plant can affect the population of the insect as well. 
• Some don’t eat things that you’d expect: about 50 species only eat dead leaves on the ground, and some (such as the Harvester on page 92) eat aphids that live on plants. Some adults don’t have working mouth parts, they only use their adult phase to breed. 
• A lot of work goes on after dark. Some caterpillars come out at night to eat (such as the Spicebush Swallowtail) and some moths only visit flowers after dark. He showed us this video about the comet orchid that attracts a special moth with a long proboscis. It is a moth that Darwin predicted would exist and which was finally found 150 years later with an infrared camera and lot of patience. 
• There are Lepidoptera that are “diet mixers,” wandering around and eating different things even as a caterpillar. 
• Caterpillars that specialize sometimes evolve to resemble the host plant. He showed us some marvelous examples of pine/juniper specialists that indeed resemble the foliage (like pine needles – long, slender and green with thin stripes). Why does that matter? It helps them hide from predators like birds. 

Owlet caterpillars on Solidago

Tasty looper caterpillar on Lobelia

And that brings us to the third piece of the relationship (and the talk). Birds eat caterpillars and for some birds they are a significant source of food, if not as an adult then certainly as a nestling.

If you love having birds in your yard then you need to love having caterpillars. Let out a big cheer every time you find a new one!

After the talk I bought David’s book and I’ve been reading a section at a time: the slug caterpillars, the loopers, the inchworms, the brushfoots, the hawkmoths, the prominents, the tussocks … each section covers a different group.

Snowberry clearwing on Lonicera (honeysuckle) - check!

I like that each species includes a list of common foodplants. I love that there is an index by foodplant! So if you see something eating on a particular plant, you can look for it that way. Want to know what's eating your honeysuckle ... look it up.

Spicebush swallowtail on Lindera - yep!

Selected ones include a picture of the adult as an extra feature but all include at least a picture of the caterpillar.

Fall webworms

I learned that fall webworms are the ones I usually notice; eastern tent caterpillars build nests in tree crotches while webworms engulf the branch. Some caterpillars like tussock moths glide to a new place to eat on a thin strand of silk (you've seen this right?); this is called ballooning.

Anisota virginiensis - wish I'd see it alive but there are probably
plenty more up there in the oak trees.

Some of them are gorgeous! Look at this pink-striped oakworm (which was dead when I found it). Nature is amazing.

While I see a lot of caterpillar evidence in my garden (chewed leaves, frass/poop), I don’t often find the actual caterpillar.

With both wasps and birds (as well as other critters) being predatory on caterpillars, I like to think that not seeing many means the ecosystem is in pretty good balance.

So next time you see a caterpillar, don't think of it as icky or creepy ... think of it as LIFE. And don't worry about chewed leaves, they grow back just fine.


P.S. This is my 200th entry on this blog. Thanks for all your support!

 

Giant Flower, At Last

About 5 or 6 years ago I went to a GNPS workday at a restoration site and one of the leaders brought some free plants to give away. I took a tiny, 4-inch woody plant known as devil’s walkingstick (Aralia spinosa). People warned me not to take it but I knew that it would be beautiful and perfect for the tropical feel around our swimming pool.

Aralia spinosa flowers at terminal ends

It is native to my area and has a huge compound leaf. When it blooms, it creates a giant inflorescence of tiny flowers (technically not a single flower despite the name of this post) that towers over perennials and other shrubs. Pollinators love the plant and swarm the numerous flowers. 

Once pollinated, each flower turns into a small purple berry – a feast for the birds. You can see a picture of the berries here. Its bi-pinnately (twice divided) compound leaves are the largest leaves of any native continental U.S. plant - up to six feet long in ideal conditions according to Floridata.
 

Aralia spinosa - a great tropical accent plant

So why would anyone steer me away from this wonderful plant? Well, it can spread by runners. So far mine has not popped up a single clone, but I know people that have fought its march across their landscape. I suspect that once it starts to sucker then it won’t stop.

I’m sure the berries, when distributed by wildlife, create new plants. I have seen it on GNPS rescue sites, scattered here and there, and appearing to be less of a suckering situation in that case and more a case of seedlings.

The first time that I saw it bloom was on the streamside near the arena at the Cullowhee Native Plant Conference. It is appropriate then to find mine blooming for the first time during the same week thatthe conference occurs this year. As I left for the conference on Wednesday, the first flowers opened and I spied a bee circling the flower.

I returned on Saturday, eager to photograph the visiting insects. Unfortunately, a heavy downpour on Friday night caused the flower to be so heavy that the plant was bent over at the top. By Saturday afternoon the weight proved too much and the twig supporting the flower snapped.

Of course I debated continuing with this post, but I decided it is part of life in the garden. If I'm lucky, enough tissue is still connected to keep the flower alive for a little longer, supporting a few insects. It is way too tall for me to deal with in terms of pruning it off anyway.

I look forward to next year's flower show now that the plant is mature enough to flower.

Buttons, Butterflies and Bees

Summer blooming shrubs are some of my favorites because, frankly, blooms in the hot and muggy days of summer are a welcome sight. These hot days I have perennials like Rudbeckia, Silphium and mountain mint (Pycnanthemum), but a blooming shrub is extra special. Like many native plants, the blooms of buttonbush (Cephalanthus occidentalis) go beyond being a pretty flower for humans to admire.

Cephalanthus occidentalis

What good is a flower if it doesn’t attract insects? (Get back to me on that.) Insects need a constant source of nectar and pollen from spring to fall. The summer blooming plants are an important part of that food continuum for them.

I don’t have the right conditions for buttonbush in my yard. It wants some sun and will do best adjacent to a pond or a wet area. I’m running out of available sunny places and I used up all my wet spots with other things. My neighbor has a beautiful, large buttonbush right next to their pond (courtesy of the forward-thinking, nature-loving previous neighbor), so I go over there to see who visits the flowers.

Bees have been the most frequent visitors to the blooms. I never tire of watching a bumblebee dive into a big blossom – in this case a 360-degree blossom! You can see some great close up pictures here. I understand that hummingbirds are fond of it as well.

  

As I watched the bees and a lone silver-spotted skipper work the blooms, a female tiger swallowtail arrived. Her wings were torn but she was hungry. I imagine she has had a hard life and is probably near the end. After she sipped nectar from several flowers, she fluttered up into the cool, green canopy of large tuliptrees (Liriodendron tulipifera) where hopefully she will lay a few more eggs for the next generation.

Female eastern tiger swallowtail

This one is just getting started

In addition to this being a great plant for insects, the unusual flower makes it perfect as a summer focal point plant. You can opine to your visitors that perhaps early settlers used the dried seed heads as buttons, but frankly I think they shatter too easily for that to be possible. Perhaps "honeyballs" is a more apt common name.

Blooms are always a combination of old and new

There's no doubt that it's great for ponds and wet areas, a hit with pollinators and a lovely way to have flowers in the summer. Birds do eat the seeds, especially ducks, I've heard. That makes it even better. Look for one at a native plant sale soon.