May23 Plants
These are a few native plants that are appropriate for rain gardens and/or plants that have special value for pollinating insects. We chose plants that are in flower or at least somewhat conspicuous on the trail right now.
Amsonia hubrictii Arkansas bluestar
This lovely plant is wildly popular and has won numerous awards. In the wild, it is found only in a few places in Arkansas, so it is native to the US but not to our area. It is fairly easy to grow, however, given full sun or part shade and well-drained soil. The flowers are an unusual pale blue but don’t last too long. It is really the foliage that makes this plant so popular. The many leaves are very thin, almost needle-like, bright green throughout the summer. But in the fall, they turn a gorgeous golden color that is probably the most attractive feature of the plant.
The flowers are said to be attractive to pollinators but consistent information is difficult to find—this plant has not been widely known for very long. One of the more widely-distributed members of the genus, A. tabernaemontana, shows up on some lists of pollinator plants.
This plant appears on some rain garden lists but would probably be best in the dryer part of the rain garden because it does not like to stay constantly wet.
http://www.rickdarke.com/Amsonia.pdf
picuous on the trail right now. Here we show it with a great companion, golden alexanders, which are a great nectar source for many bees and a host for a number of caterpillars.
Apocynum cannabinum, common dogbane
People often confuse this plant with milkweeds. It does indeed have the characteristic milky juice and it is related to milkweed. It also contains toxins like milkweed does. Dogbane is an extremely vigorous spreader and colonizes disturbed ground very quickly. It is generally not suitable for a garden setting. In the wild, however, or in a naturalized rain garden, it may be appropriate. It easily adapts to the alternate wet and dry conditions of a rain garden--maybe too easily, depending on what kinds of plants it has as neighbors.
Dogbane flowers are visited by many types of wasps and bees--it’s quite a valuable pollinator plant. It is also the source of food for larvae of the dogbane tiger moth. This very interesting white moth would normally be eaten readily by bats. However, it seems to have some elaborate defenses. Like monarch butterflies, these moths keep in their bodies some of the toxins from the dogbane plants they ate as larvae, so they taste bad and make the bats sick. But the dogbane tiger moth doesn’t have bright coloration to warn predators like monarchs do--this would be wasted on bats with their poor eyesight. Instead, the moth makes a clicking sound that apparently serves to let the bats know that this is a mouthful to avoid. A very cool example of coevolution.
https://www.illinoiswildflowers.info/prairie/plantx/dogbanex.htm
Baptisia australis, blue false indigo
This plant with its blue pea-like flowers is beautiful in the garden all year. It’s a large (3-4ft) perennial that dies back to the ground in winter but is almost shrub-like during the summer and fall. The leaves are a light bluish-green and they generally are unbothered by any pests. In the past the leaves were the main food source for the Wild Indigo Duskywing butterfly. However, this butterfly has learned to use a non-native plant, crown vetch, as a food source as well. So, non-native plants aren’t always a disaster for pollinators.
False indigo flowers are generally pollinated only by large insects like bumble bees, which are strong enough to open the large flowers. Baptisia australis var minor is native to more southern areas but is often sold in our area too. It tends to be shorter.
This plant wouldn’t be suitable in a rain garden without good drainage, but in the upper part of the depression or a shallow rain garden, it can be outstanding. The plant gets fairly tall and flops over a bit when the seed pods are mature, so it’s best for a large area. The seed pods are a striking blue-black color and they make a rattling sound when mature. This plant will seed itself around if it is happy.
https://www.butterfliesofmassachusetts.net/wild-indigo-dskywng.htm
Carex appalachica Appalachian sedge
Many sedges have become available to gardeners in recent years. There is tremendous variety in forms and in conditions preferred by the various sedges. Appalachian sedge is one of the most popular of the small clump-forming sedges. It has been used as a lawn substitute as well as a finely-textured ground cover under other plants. Its thin flowing leaves move together in the wind when the plant is massed, reminiscent of flowing water. However, the plant is quite drought tolerant. It will spread by seed and clumps will slowly enlarge, but it does not send out rhizomes.
Like their grass relatives, sedges are wind-pollinated and thus do not produce nectar to attract insects. However, they make copious amounts of pollen which may be gathered by various insects—this phenomenon has not been studied well. Larvae of butterflies such as the Appalachian Brown feed on sedges, probably on a wide number of different species. The seeds are nutritious and eaten by small animals and birds. Appalachian sedge isn’t a favorite of deer and like most grasses and sedges, it can tolerate a bit of browsing.
This plant will grow quite well under some rain garden conditions but its small stature (12”) may mean that it is best used as a ground cover under other plants. It would also probably not be suitable for the bottom of a rain garden that stays wet for a long time because it likes good drainage.
Eutrochium fistulosum (?) Gateway, Joe-Pye weed
We hesitate to include this right now, but it’s an example of the challenges we sometimes face when working with native plants and their cultivars. First, the common name Joe-Pye weed is used for many different species and even genera of plants. Secondly, various cultivars and hybrids are in commerce and all this has led to considerable confusion. This one shows up on our planting list as indicated here. However, most likely this is a cultivar of E. maculatum. We need to check!
If you are interested in figuring out the Joe-Pye weeds, this article is a good start.
Magnolia virginiana Sweetbay magnolia
Trees and shrubs are the best plants for holding on to stormwater because of the greater surface area, so it’s nice when they are also good pollinator plants. And sweetbay also appears on the list of shrubs or small trees that are appropriate for rain gardens, so this one ticks all the boxes. This magnolia has bright green deciduous leaves and it blooms in summer. It can grow as a large multi-stemmed shrub or small tree. It’s adaptable as to soil type and can even tolerate heavy wet soils, unlike most magnolias.
Most magnolias are pollinated mainly by beetles and do not provide nectar, but this one is an exception. It has a wonderful scent when in flower and is visited by many different kinds of pollinators. It is important for the larval stage of the tiger swallowtail butterfly.
As in many flowering plants, the interaction between the plant and its pollinators is more complex than first meets the eye. If you are interested, there is a great article about it.
Monarda fistulosa, wild bergamot
Bee balm (Monarda didyma) has been a favorite of gardeners for many years and there are numerous hybrids and selections available. Wild bergamot has pinkish flowers and doesn’t have the vivid color selections of bee balm, but it has the advantage of being less susceptible to mildew and other disease problems. It’s easy to grow from seed and established plants will self-seed. The flowers are attractive to all kinds of bees, butterflies, moths and even the ruby-throated hummingbird. Flowers produce nectar from early in the morning until dark, making them an especially reliable food source for many insects. The foliage is used by a number of moth caterpillars, including the small moth Coniophora monardella, which specializes on this plant.
Wild bergamot is included in lists of rain garden plants. Even though it is more resistant to powdery mildew than other selections, the leaves may still become affected. This usually doesn’t damage the plants too much, but makes them a bit unsightly so placement can be important.
Thanks to G. Manos for the great photo.
Milkweeds
We have several milkweed species on the trail. You can see three of them near Barmouth. All milkweeds have similar flowers and fruits. Most of them have flowers that are highly visited by pollinators. Here is a brief comparison of the three you can see here.
Asclepias incarnata, swamp milkweed
As the common name indicates, in the wild this species is found in wet areas. However it does quite well in average soils. Flowers are pink and fragrant. The flowers are highly attractive to a wide range of pollinators. Monarch butterflies will lay eggs on it but it is used much less frequently than common milkweed.
Asclepias tuberosa, butterflyweed
Popular milkweed with orange flowers, not at all aggressive in gardens. Despite the common name, of the three species described here this one is the least valuable for monarch caterpillars, according to the study referenced below.
Asclepias syrica, common milkweed
This is the species much preferred by Monarchs for laying their eggs. This species is considerably less desirable as a garden plant because it is quite spready. If you take a look near the gate to the cemetery, you can see that it has even spread into the lawn and survives mowing.
Read more about its use for monarch caterpillars and an experiment to make it even more useful.
https://www.frontiersin.org/articles/10.3389/fevo.2018.00169/full
Pycnanthemum muticum, short-toothed mountain mint
Like other mints, this species is vigorous and spreads by underground runners, but many gardeners appreciate the spreading quality and use this plant as a tall ground-cover or filler plant in informal plantings. Like other mints, unwanted plants pull easily and the wonderful minty smell makes it a pleasant chore. The leaves are a soft bluish-green and the flowering tips have a frosted appearance. Individual flowers are small but there are many so they make a show. In our creek-side planting mountain mint was planted amongst the turfgrass that was there and it is mixing in nicely (photo at left)..
Bee-keepers have known for a long time that this plant is a valuable source of nectar, and the 2013 Penn State Extension Pollinator trials confirmed this. Mountain mint was the #1 plant in pollinator visits, with 78 insects visiting a plant in two minutes. Many different species of bees, wasps and moths seek the nectar. The plant is also of high value because it blooms for a long period.
This plant does best in full sun or part shade. It likes good drainage but isn’t too fussy about soil and can tolerate the alternating wet and dry conditions found in rain gardens. Like other mints, mountain mint tends to not be attractive to deer, rabbits and other grazers.
