Invasive plants


It’s the very beginning of June in Connecticut.  Since mid May or so, gorgeous patches of pink, purple and white ‘wildflowers’ have appeared along roadsides.  A few years ago, my mom was visiting from Michigan around this time for a graduation.  She has been an avid gardener for many years and when she saw these flowers, she exclaimed, “oh, those wild phlox are just beautiful!”   So even a seasoned gardener can mistake this invasive plant, Dame’s rocket (Hesperis matronalis) for wild or garden phlox.

DamesRocket.GarlicMustardJAllen  J. Allen photo

Relatively speaking, Dame’s rocket (other common names include dame’s violet and mother-of-the-evening) is a newcomer to the status of invasive plant so its impacts on native species are not well studied.  It is known that it effectively forms monocultures where it has escaped from cultivation, is a prolific seed producer, and is not kept in check by pests or diseases in North America.  It is still readily available as seed commercially but is banned as an invasive in some states including Connecticut and Massachusetts. This means it cannot be bought, sold, cultivated or moved within these areas.   Unfortunately, it is still commonly included in ‘wildflower’ seed mixes for gardens in other parts of the United States.  According to a USDA distribution map, it is found throughout the continental U.S. except for the most southern parts and much of Canada.

Where did it come from?  It was introduced as an ornamental from Eurasia in the early 1600s so it’s had plenty of time to become established.  Dame’s rocket is in the plant family Brassicaceae so is related to the mustards, cabbage, broccoli, kale, etc.  The leaves, oil and seeds are edible and the plant is cultivated for its oil which is used in perfumes. Young leaves are a good source of vitamin C and they can be used in salads.  Speaking of perfume, it’s reported that the flowers of this plant produce a stronger scent in the evening.

DamesRocketLeavesJAllenDamesRocketFlowersJAllen J. Allen photos

Characteristics that can help identify Dame’s rocket include branched clusters of white, pink, and purple flowers that are about 3/4-1″ across and have four petals.  True phlox flowers have five petals. In addition, true phlox (wild) flower later in the season.  The leaves of Dame’s rocket are alternate, lance shaped and have serrated or toothed edges as shown above. In addition, leaves (except for the lowest on the stem) are directly attached to the stem and have no petioles. In contrast, true phlox have opposite leaves.  I’ll pop in a photo of true phlox below so you can see the leaves and flowers together.

 Wild blue or woodland phlox (Phlox divaricatahttps://en.wikipedia.org photo. This species is native to eastern North America.

Another distinctive feature of Dame’s rocket is the long, spindly seed pod (silique).  These form from the bottom of the flower cluster upward, so the youngest flowers (formed over a 4-6 week period) are at the tops and produce seed pods last.  Seeds and pods mature over the summer and when dry they split open releasing seeds into the soil.  Some are eaten by birds allowing for longer distance dispersal.  Each plant can produce hundreds of seeds which can remain viable in the soil for many years.

Dame’s rocket seed pods (siliques) on the left (Mark Frey, The Presidio Trust , Bugwood.org.  First year rosette on the right (Leslie J. Mehrhoff, University of Connecticut, Bugwood.org).

This plant is considered a biennial or short term perennial.  The first season of growth from seed produces a low-growing rosette of leaves which survive and remain green through the first winter.  The next season a 2-4′ flower stalk is produced as shown above.  This will dieback in the fall and some plants will produce new flower stalks in the third year.   The plant appears perennial where established in part due to the large seed supply that is produced annually.

It’s hard to want to destroy such a beautiful plant but if removal is required the methods include mechanical (pulling), burning, or herbicide applications (useful for large populations).  The best time to pull plants is in spring before seed pods mature.  Seeds can still ripen on plants pulled at this time using nutrients from the stems and leaves so for effective eradication, bag or burn the plants and remove them.  If not feasible, pile the plants in the center of the area where there is likely to be a lot of seed in the soil already.  The pile can be covered with black plastic to heat the pile and kill some of the plants.  A good approach for herbicide use is to apply to rosettes in early spring or fall to avoid injuring desirable plants nearby.  In early spring they will not have germinated yet.  Temperatures should be at or above 50 degrees Fahrenheit.

J. Allen

 

 

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Some red maples still had leaves late in the fall in 2016

 

“ November comes
And November goes,
With the last red berries
And the first white snows.”

– Clyde Watson

This fall was spectacular in its color displays both in the leaves and in the skies.And we are not done yet. A relatively indifferent  landscape can turn charming or spectacular when autumn colors abound as they have this year. Since a pictures is said  to be worth a thousand words, I will save you much reading…

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Canada geese on a pond splashed with early morning fall colors Pamm Cooper photo

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American Lady butterflies migrate south for the winter, along with sulphurs, monarchs, cabbage whites and red admirals

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Delicata squash- one of the smaller winter squash varieties

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Old house in the background with Oriental bittersweet on the left and an old Japanese maple on the right . Location is heading south from the Goodspeed Opera House on Rte 154

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Mushrooms on a dying sweet birch in early November 2016.

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Mourning Cloaks overwinter as butterflies and may be seen flying about near or in the woods on warm winter days

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It is obvious where the barberry is in these woods. Photo taken near the Gillette Castle State Park

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Honey bees are visiting mums and witch hazel this week, as well as any Montauk daisies that are still blooming

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November 6 2016 dawn over Glastonbury, Ct.

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Here is a good example of thinking ahead when planting. A sugar maple on the left and a Japanese maple on the right were probably planted over 30 years ago and are the perfect companions for great autumn color.

Take some little trips this season in our little state. There is still some good color out there, but it may not last much longer. And you may not have to go very far to get some great visual  compositions. Perhaps just as far as your own back yard.

Pamm Cooper                                          All photos by Pamm Cooper

 

 

I have a fondness for teasel (Dipsacus species) because it was common in the area where I grew up in southwestern Michigan.  Of course, I didn’t know then that it was invasive, or even what an invasive species was.  Now, on road trips between Connecticut and Michigan, I watch for the distinctive flower heads as we drive along.  I’ve never spotted teasel in Connecticut (or elsewhere in the northeast) but according to references I’ve checked, it does occur throughout the area.  There are two species that occur in the United States, D. fullonum (common teasel) and D. laciniatus (cut-leaved teasel).  Common teasel is, not surprisingly, the most common but cut-leaved teasel is described as more aggressive in its establishment and spread where it occurs. teasel-jallen J. Allen photo

If you’re not familiar with teasel, it is distinctive due to its coarsely spined flower heads, pictured above. The plants are herbaceous biennials.  During the first year of growth, a leaf rosette is formed.  In the second year, a tall (3-8 feet), prickly stem forms.  It branches at the top and forms egg-shaped flower heads.  Tiny flowers emerge first in a band around the center of the flower head and develop both up and down from there.  The prickly dried flower heads can be used as a comb and were widely used in the plants native range for combing, cleaning and raising the nap of fabrics, especially woolens (sample device pictured below from the Trowbridge Museum website). teasel-handfabricnap-trowbridge-museumThe root system has a substantial yellow tap root with fibrous secondary roots.  Seeds are attractive to birds and wildlife.  Where teasel is native (Europe, Eurasia and northern Africa), it is recommended for gardens both as an ornamental and as an attractant for birds (ie the European goldfinch) and wildlife.  The dried flower heads are sometimes used in the floriculture trade.

A fascinating attribute of teasel is that the plants are considered partially carnivorous. Carnivorous plants are those that are able to trap insects or other tiny animals and digest them or extract nutrients from them to use as a source of sustenance.  In the case of teasel, the leaves on the stem formed in the second season are fused where two opposite leaves meet on the stem. This forms a small ‘cup’ where rain water collects and tiny insects are caught there.  In a study done in the UK by Peter Shaw and Kyle Shackleton and published in 2011, it was shown that common teasel plants with dead fly larvae placed in the water in the ‘cup’ had a 30% greater seed set and seed biomass than plants with no larvae.  While the larvae did improve seed production, they did not see an increase in overall plant growth/biomass.

To distinguish between common and cut-leaved teasel, both the leaves and flower heads can be used. See the images below for comparison.

teasel-common-leaves-bugwoodteasel-common-flower-bugwood Common teasel leaves and flower heads.

teasel-cutleaved-bugwoodteasel-cutleaved-flower-bugwood Cut-leaved teasel leaves and flower heads.

All above photos from: ©Richard Old, XID Services Inc., Bugwood.org

The first report of common teasel in the U.S. was dates back to the 1700s but no additional reports are known until the 1800s when it was described in Oregon, Michigan, New York and Niagara Falls, Ontario. Since that time, it has spread and been confirmed throughout the contiguous states except in the northern great plains and the southeast.  Cut-leaved teasel was reported from Michigan and New York prior to 1900.  Both species are considered invasive in the U.S. but without a legal status.  While described as being ‘invasive’, states don’t necessarily have a legal status limiting the distribution of these plants. Connecticut does not.

Besides using the dried flower heads, root extract has historically been used to treat a variety of ailments including stomach upset, pain, inflammation, nervous system maladies, and most notably, and more recently, in the treatment of Lyme disease. It is reputed to draw the bacterial pathogen causing Lyme disease out of tissues where it is protected from antibiotics into the blood stream where it is susceptible to them and to the body’s immune system. This is NOT a recommendation to use teasel in the treatment of Lyme disease in the absence of treatment by a medical professional.

J. Allen

 

Masses of white flowers are a common and beautiful sight along Connecticut’s roadways and in fields this time of year (late May through June). While there are (of course) many shrubs and trees bearing white flowers, one of the most predominant is multiflora rose (Rosa multiflora).   This rose is native to Japan, Korea and parts of China and has become invasive throughout eastern North America.  While it is invasive and is a real problem, we’re sort of stuck with it overall so go ahead and enjoy the gorgeous blooms.MultifloraRoseBush.JAllen  Photo: J. Allen, UConn

Multiflora rose was first introduced into the U.S. as early as 1866 for use as a rootstock for ornamental roses. In the 1930s, the U.S. Soil Conservation Service began to recommend it for erosion control and as a ‘living fence’ for livestock.  In the 1960s plants were even distributed to landowners for free to encourage planting as cover for wildlife including birds and rabbits and as a food source for songbirds.  Thanks to the songbirds, many seeds have been distributed to new sites because they do like to eat the nutritious rose hips (fruit).   The plant is now considered a noxious or invasive weed in many states including in Connecticut “…prohibited from importation, movement, sale, purchase, transplanting, cultivation and distribution under CT General Statutes §22a-381d”.

MultifloraRoseflowers.J Photo: J. Allen, UConn

It’s pretty easy to recognize multiflora rose when it’s in flower but also once the bloom period is over. Flowers are borne in clusters of mostly white but sometimes slightly pink flowers that are ½ to 1” across and have five petals.  Leaves, too, are distinctive.   They are alternate and compound, having 5-11 oval leaflets with toothed margins.  The base or petiole of the leaf is fringed.  Even the thorns are unique to this species.  They are large, curved backwards and have an oval base.  If a thorn is removed, it will leave a visible oval scar on the stem.  They’re pretty serious thorns and are reported to be capable of puncturing tires and leaving a painful gash in skin.  Overall, this plant can reach a height of about 15’ with long, arching stems.  It can also be a climber and at times you will see it spreading up against other vegetation or structures.  For some great info and photos of the thorns, fringed petals (stipules), and more check out this web page: http://na.fs.fed.us/spfo/invasiveplants/factsheets/pdf/multiflora-rose.pdf

MultifloraRosespreading.J.AllenMultiflora rose spreading through a natural area and up another tree in the background. Photo: J. Allen, UConn.

Reproduction is by seeds (prolific at 500,000 to a million seeds per large bush per year), suckers and by rooting at the end of stems that arch over and touch the ground. Widespread dispersal is via birds that eat the fruit and expel the seeds.  It’s reported that seeds which have passed through a bird’s digestive system germinate more readily.  Invasiveness is enhanced by not only the huge potential for seed production but also by the fact that the seeds can remain viable in the soil for up to 20 years.

Like other roses, the hips and other plant parts (leaves and flowers) are edible. The hips are high in Vitamin C, carotene and essential fatty acids.  It’s recommended to harvest after the first frost when berries are softened and sweet.  They can be eaten raw but do contain some hairs between the flesh and the seed that can cause irritation.   Leaves, flowers and hips can be used to make tea.  To make rose hip tea, mash the fruits and steep in hot water.  Leaves are best when young as the hairs on the undersides can become stiffer and less palatable later in the season.

Some of the broader impacts of this plant, like other invasives, include displacement/replacement of native plants and the resulting impacts on habitat and food supply for native wildlife. Pasture lands are adversely affected when these thorny plants encroach and reduce forage area for livestock.  Even forestry operations are affected because of the impenetrable, thorny thickets that form, reducing access and making work difficult.  Multiflora rose can thrive in a wide range of habitats from open sunny sites to woodland edges.  It can survive on a range of soil types but is not found in extremely dry or wet sites.

Control methods used include physical or manual removal including mowing, digging, and prescribed fire. Chemical herbicides can be used as either a cut stem (fall) or foliar application.  Biological controls are not yet available.  A virus that causes rose rosette disease limits growth in some areas but that also affects ornamental roses.  An insect, the European rose chalcid, is being studied for potential use.

By J. Allen

 

Comfrey flower, photo by C. Quish

Comfrey flower, photo by C. Quish

Not all pretty flowering plants in small, four-inch pots siting on the nursery bench are as innocent as they appear. Beware the sneaky aggressor! About five years ago the delicate and rare clear blue color of the comfrey blossom, shyly wooed me into taking it home. What could one more plant hurt in the side garden abutting the wild side of the neighbor’s yard hurt? Well, it hurt plenty. I have been cursing the day I planted it.

Comfrey gone wild. photo by C.Quish

Comfrey gone wild. photo by C.Quish

Comfrey spreads incredibly fast. It is a hardy perennial with a deep and extensive root system. And its seed drop and are spread to create new plants elsewhere. The neighbor loves it and encourages its spread which doesn’t help my eradication efforts on my side of the property line. I suppose it makes a better fence than wood and nails, and he enjoys the view.  The bees enjoy the flowers, too. Dozens of honey bees can be found busily entering flower after flower, not caring how close I get to almost petting them.

Bee feasting inside comfrey flower. photo, C.Quish

Bee feasting inside comfrey flower. photo, C.Quish

Comfrey is botanically known as Symphytum sp. and is a member of the borage family. The Latin name means ‘grow together’.  It was first brought to America with the English as a healing herb. I contains a high level of the chemical allantoin which aids in cell formation, healing. It also is reported to contain pyrrolizidine alkaloids, known to cause liver damage when taken internally in large amounts. The leaves can be crushed or bruised to be placed on external skin areas to heal wounds and broken bones. I only use the plant as an ornamental and to spread into the neighbors neglected ‘wild’ area.

Comfrey has a tap-root, growing about 18 inches deep in the soil. It does a great job of breaking up compacted ground, accessing the minerals and nutrients out of reach of shallower plant roots. For this reason, comfrey leaves are a great addition to the compost pile, as those deep-seated nutrients of the ground are now taken up by the roots to be stored in the comfrey leaves. Once the microbes in the compost pile break down the comfrey leaves into its basic chemical elements, the nutrients are released into the compost and made available for use by other plants. Just don’t put any of those spreading roots into the compost pile. Keep any seeds out of the compost also.

So heed those enticing words on the plant labels when the just mention the words, ‘fast grower’ or ‘spreading’. Sometimes they really mean it!

-Carol Quish

 

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Queen Anne’s lace or wild carrot (Daucus carota) is native to parts of Europe and Asia and is naturalized in North America and Australia.  It is a biennial in the family Apiaceae.  Domestic carrots are cultivars bred from its subspecies D. carota ssp. sativus.   Being a biennial, it grows a leafy mound of green fern-like foliage the first season and then produces flowers the second year.  Flowers are produced from June through August. The tiny white flowers are borne in flat to slightly rounded clusters called umbels.   Before they’re fully open, the flowers may have a pink to reddish caste.  In some umbels, there is a single dark red flower in the center.  This is said to be a droplet of blood where Queen Anne pricked her finger while making the lace.  The function of the red flower is thought to be an attractant for insects.

The root of the wild carrot is edible when it is young but becomes woody and unpalatable as it matures.  As early as 2000 years ago the crushed seeds were used as a contraceptive.  Research has somewhat supported this; in studies with mice wild carrot was found to disrupt the egg implantation process.  It is not recommended here to use wild carrot for this purpose!

Wild carrot has a poisonous look-alike plant, poison or water hemlock, so it should never be consumed  unless it is absolutely certain that it has been identified correctly.   The leaves of Queen Anne’s lace can cause irritation known as phytophotodermatitis.  When the sap from the leaves gets on the skin and it is then exposed to sunlight, a rash may develop.   This plant is considered a noxious weed by the USDA because of this and because it is a pest in pastures, displacing desirable native plants.

Queen Anne’s lace is also a beneficial plant because it can help attract insect parasites and predators of pest insects to the garden.  Beneficial wasps, ant lions and green lacewings either feed on the nectar or pollen of the flowers or are attracted to aphids on the flowers.

Many animals use the wild carrot plant as a source of food or shelter.  Some that use it as a food source include the eastern black swallowtail butterfly, honeybee, green stinkbug, differential grasshopper, golden northern bumblebee and green lacewing.  Many animals use it for shelter including the eastern black swallowtail, aphids, dog ticks, Chinese mantid, American goldfinch, black and yellow argiope, eastern bluebird, green stinkbug, eastern mole, differential grasshopper, northern mockingbird, common grackle, green lacewing and chiggers.   Other plants commonly found growing with wild carrot include goldenrod, milkweed, pokeweed, smooth crabgrass, red clover, English plantain, devil’s beggar-tick, spotted Joe-pye weed, lamb’s quarters, common ragweed, jimsonweed, black-eyed Susan, Kentucky bluegrass, wild strawberry, and common mullein.

J. Allen

Nope, not Oster, Waring or Hamilton Beach, these are plants that are called into service for the purpose of unifying a planting of individual elements and to give it coherence. Homeowners and professional garden designers devote hours to planning landscapes that will be interesting and attractive throughout the growing season and beyond.  Much is attention is given to the “bones” of a garden –  plants that provide structure and give the landscape interest into the bleak mid-winter. Secondary plants contribute the seasonal interest, texture and rhythm. Then there is a third tier, those varieties that serve the valuable function of tying the whole composition together.

Poppy 'Queen Alexandra' and Cranesbill, McInnis photo

Annuals that self-sow are often the star performers in this category; they can be selectively thinned or transplanted for the desired effect.  They run the gambit from the delicate and well-behaved Nigella to downright coarse and aggressive – the purple form of Perilla, for example. Cosmos and cleome contribute cheerful interest toward the back of a border and will soften the heavy appearance of shrubs. Each plant weaves its unique character through a planting, often with a result that looks more carefully planned than it really was.

Purchased annuals can be used to achieve the same informal effect. Since contemporary gardens rarely adhere to the rigid formality of Victorian carpet bedding designs, weaving annuals through established shrubs and perennials is an attractive way to display their assets, prevent them from flopping, and create a lush display. These workhorses provide a long season of color, and when they do fade, tend to drop out of sight.

Many perennials will return in the spring with a new generation of seedlings in tow. The list is endless, but some personal favorites are: Verbena bonariensis, pops of purple bloom randomly scattered about; Bronze Fennel (Foeniculum vulgare ‘Purpureum’) with its gossamer smoke; Rose campion, (Lychnis coronaria) a vigorous biennial well-adapted to hostile sites; Johnny Jump-Ups (Viola cornuta) , always a welcome surprise in the spring; Snapdragons (Antirrhinum majus) and Columbine (Aquilegia canadensis). Remember that plants that self-sow may not always come true from seed, particularly the hybrids. But, an advantage to this is that the undesirable forms can be culled and preferred ones encouraged.

A bed unifier can double as a living groundcover, such as Speedwell (Veronica spicata) or Cranesbill (Geranium sp.) that will allow taller plants to emerge and harmonize.

Dense groundcovers, such as the sedums, Moss Phlox (Phlox subulata) and Dianthus species serve as a living mulch that discourages weeds and add interest.

Liatris emerging through sedum, McInnis photo

Then there are the happy accidents; the bird-delivered False Solomon’s Seal (Smilacina racemosa), the Lady’s Mantle (Alchemilla mollis) that arrived as a stowaway in a container-grown hydrangea, or a Joe Pye Weed (Eutrochium purpureum) whose seeds were deposited by October breezes the previous year. Consider keeping these volunteers who are already thriving in conditions they themselves have chosen.

A word of warning – some species in some locations cross the line from welcome additions to the party to obnoxious trespassers. Some consider Perilla a noxious weed, for others it’s a simple matter of pulling unwanted plants and cooking them in a Japanese-inspired stir fry. Over time, Rose campion or Bugleweed (Ajuga reptans) can consume a bed, invade a lawn, snuggle into the cracks of a sidewalk and from there scout out new locations to conquer.

Ajuga invading a lawn, McInnis photo

What about mulch? For this gardener, mulch (natural color, PLEASE – and NO cocoa mulch – it’s lethal to dogs!) is merely a temporary placeholder to discourage weeds and add organic matter to the soil while the surrounding plants are filling in.

James McInnis

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