THE JAPANESE ANGELICA TREE

Japanese Angelica Tree, Aralia elata,Wissahickon Valley Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata,Wissahickon Valley Park , Philadelphia, Pennsylvania

This tree is found throughout Philadelphia, in Fairmount Park, in alleys and neighborhoods. It has a silvery thorny trunk and  produces a striking crown of white to pink flowers in August.  The most dense stands can be found in The Wissahickon Valley Park, but it is also found in abundance in West Fairmount Park, in such locations as the Horticultural Center and along Chamounix  Drive.  In Morris Park it is spreading rapidly, where multiple stands of seed producing specimens have been identified.

The Japanese Angelica Tree is an emerging invasive in the region, and where it has become established there has been a drastic change and disruption to the natural environment. This tree creates a canopy of shade so dense and a root system so interconnected that native trees, shrubs and herbaceous plants are left to die in the wake of this aggressive alien species.  With the loss of these plants, which have grown here for thousands and millions of years, is a loss of a complex web of habitat that sustains the life of the forest.  The insects whose patterns of sustenance, such as food and reproduction, are species-specifically dependent, lose their habitat and become locally extirpated with each infestation of the Japanese Angelica Tree. Birds that need insects for survival, will also be displaced as there is no food. When a species has evolved over the millions of years, it does so in a system of species and interactions, often with multiple variables.  When an introduced species comes into a system, it has the potential to radically change the variables of the system.  For example, the Japanese Angelica Tree has the ability to block sunlight, which is one variable to a natural system that has an immense effect. It is like a dark cloud that moves over a community of plants, an invading force, permanently shading the area through the entire growing season, and on top of that running a dense network of roots all through the soil that absorbs the moisture and nutrients that will no longer be available to the original community of plants. This is enough to kill off many species of plants and their species-specific insect dependents, and this amounts to localized extirpation, the elimination of a species from its host habitat.

There is nothing to stop these invasions. Acre after acre of Philadelphia’s Fairmount Park system has fallen victim to this species.

This is where our story begins.

Japanese Angelica Tree, Aralia elata, Wissahickon Valley Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata, Wissahickon Valley Park , Philadelphia, Pennsylvania

Take a walk through the Wissahickon Valley Park and the Japanese Angelica Tree is everywhere. In the late summer, the white inflorescence  crests the landscape and the spiny trunks line the trails.

Making matters more confusing is that there is a native tree that is very similar to the Japanese Angelica Tree (Aralia elata), called the Devils Walking Stick (Aralia spinosa), which does not grow in the Philadelphia region, but does grow naturally in Western Pennsylvania as well as parts of New Jersey, Delaware and much of the Eastern U.S.

The two species are related. The native one, in its natural range, is part of the natural system, while the exotic one has become a noxious pest.

For a while we thought the Japanese Angelica Tree was the native Devil’s Walking Stick. What we did not know was that even if it was the native tree, we were not in the natural range for the American Arialia spinosa. So even if it was the native Devils walking stick, it would still be out of its range in Philadelphia and therefore out of place.   We have learned that even ‘native’ plants still have this range, which varies throughout the country plant by plant, and if the plant is outside its historical, evolutionary range, than it is an alien.

We do not know what to expect from aliens. Usually it is something bad or out of the usual order. With plants, this is the case for many specimens that are introduced from other regions. They can take over and create problems. Insects such as the Japanese beetle (Popillia japonica) and now the stinkbug (Halyomorpha halys) are prime examples of alien species.

When examining native range maps of the many indigenous North American Plant species, as presented by the U.S. Geological Survey, there is to be found an intriguing world of plant species and their localized areas. The United States is divided up into a complex and entirely different world than what we generally perceive it to be; there is an astounding geographic dimension to the U.S. that  encompasses thousands of species, with real borders, completely different than those of states, counties and provinces. It is as if there are whole worlds of speciation and  delineation that we are for the most part completely unaware of!

We had no idea that in the Middle of Pennslvania there is a line where the native Devil’s Walking Stick’s range comes to a natural end.  And between this borderline and the infestations of the Devil’s Walking Stick’s genetic relative, The Japanese Angelica Tree in Morris Park is where our adventure starts out.

Japanese Angelica Tree, Aralia elata,Wissahickon Valley Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata,Wissahickon Valley Park , Philadelphia, Pennsylvania

We had always admired the binnately compound leaf of the Japanese Angelica tree, as illustrated above. What is pictured is one leaf, composed of a series of branches holding leaflets, in sets of two along each branch.

The Philadelphia Parks and Recreation Staff, technician Luke Rhodes and Land Steward Thomas Dougherty alerted us to the designation of the species, the invasive Aralia elata, the Japanese Angelica Tree. After double checking this information out, our next question was what can we do about it?  We tried to chop them down, but the extensive root systems would send up new shoots.

Tom And Luke of Fairmount Park saw that Isabelle and I were serious about trying to eradicate this invasive, and we formed a partnership, and the eradication process had begun.  The Philadelphia Parks and Recreation Staff tasked us volunteers with mapping the infestations and identifying target areas for eradication.  We chose sites that were the closest to forest areas that had the least invasives and the highest diversity of native flora.  Tom and Luke then applied the herbicide Garlon 4 ultra with a green dye ( to help identify applied specimens) in a basal bark application to the mature seed-producing specimens in a first pass attempt at eradication.

Japanese Angelica Tree, Aralia elata, Morris Park ,  Philadelphia, Pennsylvania

Japanese Angelica Tree, Aralia elata, Morris Park , Philadelphia, Pennsylvania

The process started: The mature specimens were treated with herbicide in the late winter, and they died by May or June. Above, the herbicide is applied around the bark at the base of the tree leading to the technical jargon basal bark herbicide application.

Japanese Angelica Tree, Aralia elata, Morris Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata, Morris Park , Philadelphia, Pennsylvania

Tom and Luke take a quick break. Luke is resting on a weed wrench, a tool that we volunteers were using to remove another invasive, the Burning Bush, the euonymus alatus.

Japanese Angelica Tree, Aralia elata, Morris Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata, Morris Park , Philadelphia, Pennsylvania

Isabelle cracked a good joke to get us all to smile: From left: Jason Puglionesi, Sean Solomon, Luke Rhodes, Tom Dougherty.

Japanese Angelica Tree, Aralia elata, Morris Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata, Morris Park , Philadelphia, Pennsylvania

Fast forward to late Spring 2012, and the treated specimens have leafed out, only to begin dying off soon after.

Japanese Angelica Tree, Aralia elata, Morris Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata, Morris Park , Philadelphia, Pennsylvania

By summer, the trees are completely dead.

Japanese Angelica Tree, Aralia elata, Morris Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata, Morris Park , Philadelphia, Pennsylvania

This is last year’s batch, treated in February of 2011, they are apparitions at this point, the whole stand has been crashing to the ground one by one.

Japanese Angelica Tree, Aralia elata, Wissahickon Valley  Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata, Wissahickon Valley Park , Philadelphia, Pennsylvania

Here is a closer look at the fruits of the Angelica Tree, found in early August on a dense stand in The Wissahickon, in the Creshiem Valley section. Each tree produces hundreds of seeds on display in multiple circular clusters. The ripe seeds attract birds, who end up helping the plant spread its range rapidly. The irony is that while the birds get instant gratification from the berries, their spread is actually destroying habitats of other plants the birds depend on in the long term.

Japanese Angelica Tree, Aralia elata, Wissahickon Valley  Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata, Wissahickon Valley Park , Philadelphia, Pennsylvania

Here is a seedling right next to our house, in an area where there had been no mature seed-producing specimens in the immediate vicinity. The seedlings number in the hundreds, and we have to hand pull each and every one. This seedling can grow up to three feet tall in one growing season.  In the areas where the seed-producing mature specimens have been eradicated, the now sunlit forest floor has erupted in a mass of seedlings so dense they number in the thousands. Many native plants and trees are among this startling infestation of noxious weeds, which necessitates hand pulling.

A daunting task to initiate!

 

Japanese Angelica Tree, Aralia elata, Morris  Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata, Morris Park , Philadelphia, Pennsylvania

Meet the Friends of Haverford Trails- they are a neighboring Park Friends group working on an area that is part of the Cobbs Creek watershed. They came out to visit our site in July and were glad to lend a helping hand with our Aralia elata problem.

From left after Isabelle: Barry Pinheiro, Frances Heron, Joe Walker, Jane Horwitz, Roy Sandstrom and Peter Puglionesi.

We were able to pull a whole infestation of seedlings in a half hour! We spent the rest of the time touring the site and talking about native plants and trees as well as our volunteer projects.

We use thick gloves with those spiny stems.  The pulled specimens are scattered about the site, where they will die and return to organic matter, hopefully to be used by a native plant of local provenance.

Japanese Angelica Tree, Aralia elata, Morris  Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata, Morris Park , Philadelphia, Pennsylvania

We discovered Jack-in- The Pulpit, Joe-Pye-Weed, White oak seedlings, Sassafrass and Dogwood in the area we worked on.

 

Japanese Angelica Tree, Aralia elata, Eradication initiation, Morris Park ,  Philadelphia, Pennsylvania

Mass of Seedlings.

Japanese Angelica Tree, Aralia elata, Eradication initiation, Morris Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata, Eradication initiation, Morris Park , Philadelphia, Pennsylvania

Our friend Jason whom you have met from our Garlic Mustard adventures of 2012,  and his friend Skylar came out on August 2nd to help out as well, and we pulled seedlings for a short afternoon. We also pulled the invasive Japanese Stiltgrass along the trails. Skylar is holding a red Hickory leaf. Just the slightest hint of Fall in the air, eh?

Japanese Angelica Tree, Aralia elata,Wissahickon Valley Park ,  Philadelphia, Pennsylvania
Japanese Angelica Tree, Aralia elata,Wissahickon Valley Park , Philadelphia, Pennsylvania

Last but not least, is a site of great interest in Fairmount Park, this is just a few yards north of Mom Rinker’s Rock, where the Toleration Statue is located.  Besides the lovely views and colorful history, this is a site of huge importance to us because growing there is the native shrub Hearts-A-bustin’, the Strawberry bush, the Euonymus americana, a beautiful and elegant shrub that has been passed over by the horticultural industry  in favor of the previously mentioned Burning bush, the invasive and noxious introduced but closely related shrub, Euonymus alatus, which has infested many areas of the Wissahickon as well as Morris Park. In fact the Euonymus alatus is found growing side by side with the native Euonymus americana, the Hearts-a-Bustin’.

Even more disturbing is that the Hearts-a-Bustin’ is being encroached upon by an infestation of  an aggressive  stand of the Japanese Angelica Tree!  In all of our adventures through the Fairmount Park System, we have never seen the Hearts-a-Bustin’, except at this one unusual site, and yet this special area is threatened by this same invasive as found throughout the park. A few good workdays the way we have been doing it could really help out this little place, where do we sign up?

Lessons learned: Nothing is as easy as we think it might be. Cannot underestimate a loaded seedbank.

While Humans have certainly created many conditions that are leading to environmental disfunction, habitat loss and species extirpation and extinction, there are some things we can do, and have fun doing them.

Traveling to nearby areas helps one learn more about your own area. In fact traveling and exploring is a great educational experience, and you will bring home a great perspective and knowledge.

A species outside its natural range has the potential to be a dangerous species: when considering plants it is all about the location, the provenance. A species will do everything it can to propagate, as it is programmed to do. When outside of its evolutionary system, it can become an unchecked variable, creating disorder to habitats that are not in any way evolved to absorb such a disturbance, requiring us humans to make ourselves useful and intervene.

Isabelle Dijols with a blooming Japanese Angelica Tree, Wissahickon Valley Park at Lincoln Drive, August 26th 2012
Isabelle Dijols with a blooming Japanese Angelica Tree, Wissahickon Valley Park at Lincoln Drive, August 26th 2012

THE JAPANESE ANGELICA-TREE RAPIDLY INVADES MORRIS PARK

ARALIA ELATA. THE JAPANESE ANGELICA TREE HAS EMERGED AS AN INCREASING THREAT.  NUMEROUS, RAPIDLY GROWING INFESTATIONS ARE BEING DOCUMENTED ACROSS THE PARK. MECHANICAL REMOVAL IS DIFFICULT AND PROBLEMATIC. AREAS IN IMMEDIATE NEED OF RE-FORESTATION ARE INSTEAD EXPERIENCING ECOLOGICAL DEGRADATION BECAUSE OF THIS SPECIES.

 Aralia elata, THE JAPANESE ANGELICA TREE, SPINES ON THE TRUNK
Aralia elata THE JAPANESE ANGELICA TREE, SPINES ON THE TRUNK

An Angel or the Devil?  There has been so much confusion over this species because of its resemblance to the native North American species Aralia spinosa, or the Devil’s Walking Stick also called  Hercules’ Club.  For the longest time we thought it was the native tree growing in Morris Park, and being that it does have very interesting qualities we embraced this plant.  Its beautiful bi and tri-pinnately compound leaves give a sense of refined elegance to the plant world, in that there is a degree of replication and logical order in a single leaf arrangement.  Also the flowers, which bloom in late August throughout September have a commanding presence and pleasing white and subtle pinkish color.  The dark berries it produces are quickly gathered by birds, furthering the plant’s range as the birds deposit the seeds elsewhere.

Of course we looked it up in The Vascular Flora of Pennsylvania, the Annotated Checklist and Atlas by Anne Fowler Rhoades and William McKinley Klein Jr., published 18 years ago in 1993.  What is called The ‘Devil’s Walking stick’ was listed as native and our county of Philadelphia was included in its native range. This is a clear example of how confusion quickly arises from the usage of common names which is why we use and repeat the Latin names, often to the point that the common name is secondary in our discussion.

Being satisfied with our information we did not investigate the plant further, just left it at that for the time being.  We did notice how aggressive this tree was.

The similarities to the native Hercules’ Club (Aralia spinosa) had us fooled, along with many others throughout the twentieth century. In the meantime, this species, the Aralia elata, introduced into Fairmount Park in the early Twentieth century  according to the Trees Of Pennsylvania (Rhoades and Block, 2005) was  for  this whole time invading forests, ever increasing in size and expanding its territory to outside of Philadelphia and beyond. Now Aralia elata is considered an emerging invasive by the New Jersey Invasive Species Strike Team , and was featured on their 2010 list of plants to watch. The New Jersey Invasive Species Strike Team  has a sophisticated online map of the  most problematic emerging invasive plants (see interactive map  feature).  It is disturbing to view the prevalence of  Aralia elata on this map. Populations are found throughout the state. It is also rapidly invading forested sections of Long Island in New York State.

Aralia elata, looking up at an infestation of the trees in the winter sky
Aralia elata, looking up at an infestation of the trees in the winter sky

The Staff of Fairmount Park (now Parks and Recreation) alerted us to the non-native status of this species. They had by this time already made a ‘first-pass’ effort at controlling a large and disturbing colony in Morris Park, in what is our area of scope.

The learning curve went from there. There is nothing better than being pointed in the right direction. We consulted The Plants of Pennsylvania by Rhoads and Block, the second edition, printed  4 years ago in 2007. Here this ‘Asian Native’ plant was listed as being “naturalized in disturbed woodlands” especially in the “southeast” portion of our state.  Reading The Trees of Pennsylvania, we got a more complete story. We can now distinguish between the native to Pennsylvania (but not Philadelphia County) Hercules Club, Devils Walking Stick, (Aralia spinosa) and the invasive exotic Japanese Angelica Tree, (Aralia elata).

Both plants are in the Ginseng Family, Araliaceae.  The botanical differences? First of all, we have not ever seen a native to North America but not Philadelphia Aralia spinosa, ‘Hercules Club’. Hopefully that will change, and our horizons will someday be expanded on this front. The natural range of the Aralia spinosa in Pennsylvania is further west in the state.  If one was found in Philadelphia, it would be considered introduced. Aralia spinosa lacks historical origins in Philadelphia county, and Morris Park. A native species that lacks the local provenance of an area it is introduced to, has the potential to become problematic.

The botanical differences are distinct , but to the discerning eye.  For now, two differences to start with: the flower on the native Hercules’club (Aralia spinosa) is borne on a distinct stalk, where the inflorescence radiates from a vertical spine.  The non-native Aralia elata has either an extremely short stalk or none at all. The inflorescence radiates out from one distinct bottom point.  The leaf is the next to look at:  In the native Spinosa, there is a border around the leaf, much like Arisaema triphyllum (Jack in the pulpit), whereas the non-native elata has the leaf veins extending to the very edge. (However this is not the most reliable difference in making a definitive distinction between these two closely related species)

AN INFESTATION OF JAPANESE ANGELICA TREE NEXT TO AMERICAN CHESTNUT
AN INFESTATION OF JAPANESE ANGELICA TREE NEXT TO AMERICAN CHESTNUTÂ

Having studied the published data on the Aralia, we then decided to check for ourselves the field data.  We chose multiple populations in Morris Park to examine as well as ones in The Wyndale Woods in Cobbs Creek Park, multiple populations in the Wissahickon Valley Park and West Park near Memorial Hall.  The field data examinations were performed during the blossoming of the flowers and the setting of seeds, which occurred between August and October of 2010.

Botanical Descriptions are the most valuable and appreciated in the field, where we are confronted first -hand with the plant in question. We  hang-on to every word of the description and look carefully at the plant, more than we ever have before.  Out of context a botanical description is useful only to a degree, but on site, every aspect is important in positively identifying the plant.

All of our analysis of the botanical features that differentiate Aralia elata from Aralia spinosa were found to be congruous with the conclusions of  the multiple written sources we consulted.

Aralia elata
Aralia elata

The 12 year old Fairmount Park Master Plan (Volume 2 Cobbs Creek 1999 see ‘park specific’ plans for Cobbs Creek) does not  mention the invasive Aralia elata at all. Why this is could be of two reasons:  That it had  not yet spread into Cobbs Creek and Morris Park (considered part of Cobbs Creek) or, the confusion of its non-native, invasive status was unknown at the time.  Most illustrative of this is the description of the Wyndale Ave Forest, site name ‘Wyndale High Quality Woods’ (v105).  In the description, this area, which is very close to Morris Park, reads:

“This is a high quality area which is considered to be one of the nicest stands of woods in Cobbs Creek Park. Identifying this as a high quality woods and protecting this area against invasion by exotic vegetation and human disturbance is recommended. A survey to identify rare native flora and fauna should be performed to ensure protection of this contiguous parcel of of woods, as it could serve as habitat for various species which are not found in disturbed sites. This area should be maintained by routine exotic removal on the fringes and trash removal by volunteers.”

This beautifully written, concise statement by those who were tasked to assess the whole of the Cobbs Creek/Morris park portion of Philadelphia’s Fairmount Park, has become words cast in bronze, and carved in stone for us at the Sanguine Root. What could better describe our day-to-day life in preserving Morris Park than this eloquent statement written twelve years ago?

The Fairmount Park Master plan, written in the last millenium, over 1/10th of a century ago, is still relevant, and for us, still is a goal to be achieved, especially in what it has to say about Morris Park. In the Sanguine Root Office we have a printed out copy of the pdf in a three ring binder.

However, what is not said in this soon becoming ancient but  still relevant document is the status of the Japanese Angelica Tree (Aralia elata). This species is not even mentioned in the list of Invasive species in Cobbs Creek Park. This was 12 years ago. Was the species not prevalent 12 years ago or was there still confusion about its status and it was overlooked as a problem?   These are our questions, and hopefully they will be answered in time. So, we decided to visit our neighbor, the Wyndale High Quality Woods, V105, and this is what we found: We were so happy to see such a beautiful forest! Oaks, Beeches, ferns, even in late autumn, this place was  the real Pennsylvania through and through. We found an American Chestnut, Castanea dentata. Just about one mile from Morris Park.  However, we  found a significant infestation of Aralia elata, the Japanese Angelica tree. Hundreds of specimens.  This is an alarming situation. First and Foremost, we need to alert the authorities, The Parks and Recreation department of the City Of Philadelphia.  We did this already.   While Morris Park is our Focus and area of Scope, we would be ready at almost any time to also help out with our neighbor, the  Wyndale Ave High Quality Woods, site V 105.

An Angel or the Devil.  The question pricks at our consciousness at every turn, as morality is a human concern and for good reason. However, in the plant and animal world this is irrelevant. Lucky we, that we have the luxury of making distinctions. We are a versatile species, us  Homo sapien sapiens. we can create the problem as a species and we can work to reverse the problem, and care passionately about it on top of that, for whatever that is worth in our estimation.  We, as a species brought the Japanese Angelica tree to our forests.  We thought it was pretty, or it was completely overlooked, introduced  along with some other introduced tree or flower, during the craze of the Centennial Exhibition or in the aftermath.  Regardless, we have to deal with it now.

Aralia elataThe Japanese Angelica tree,  Aralia elata crowds out native species, Morris park philadelphia
Aralia elata  The Japanese Angelica tree, Aralia elata crowds out native species, Morris Park Philadelphia

DEALING WITH ARALIA ELATA

Aralia elata, the Japanese Angelica tree, grows quickly and has a habit of growing in clumps, that increase in size exponentially . The beautiful bi- and tri-pinnately compound leaves are very large, and they shade out the sun preventing other species from growing. On the soil side of things, Aralia elata grows underground runners every which way interfering with any native species at the site.  The clump becomes a monoculture as other species decline in population and become extirpated.

Removing them by hand can be done, but only in certain situations.  If they can be gently enough teased out of the ground (to disturb the soil as little as possible) but all of the plant must be removed.  Any root fragment left behind will grow into a new tree.  As a temporary step, even just cutting the tree will at least prevent it from going to seed and will slow down its growth of runners.  If there are other young  native tree saplings nearby, hand-pulling can disturb the soil and threaten the native plants.  The runners and roots of Aralia elata often wrap around and penetrate the root systems of other plants. From a hand-control perspective, cutting it down, and then monitoring that one specimen season after season after season, along with any others could work in eradicating it.

Isabelle makes an assessment of the largest infestation  Aralia elata,  Morris Park Philadelphia
Isabelle Dijols makes an assessment of the largest infestation.  Aralia elata, Morris Park Philadelphia

Our situation in Morris Park is beyond a few specimens that we could manage by repeated cutting, even though we are on the site every day.  In one area there is an estimated 1000 specimens, ranging in trunk size from 8 inches thick, to mere whips. This is a monstrous infestation, and is a great challenge.  The Environmental Stewardship Division of Fairmount Park has, as mentioned earlier, started to address this one problematic patch.  Also growing at the site are Beech and Oak saplings that are the future of the forest, if the Aralia elata can be eliminated.

On this Friday, February 18, 2011, the staff of the Sanguine Root , in partnership with the Environment and Stewardship Division of Parks and Recreation will be taking steps to eliminate the Aralia elata at this site.  We will be getting an early start at 10 AM, so as many trees as possible can be eliminated.  Qualified Fairmount Park Restoration Field Technicians will be working with us, applying herbicide to the stumps as we cut them. We are not sure which one, but possibly triclopyr, which is recommended by the New Jersey Invasive Species Strike Team (see the Control Methods pdf).  The Sanguine Root Staff is not qualified, certified or authorized to use any herbicides. It is unfortunate we have to have them used at all, but the situation is that difficult and serious.

We are also racing the clock with this project because once the trees begin to exit dormancy they will start producing sap which flows upwards, and would push out any herbicides applied to the cut stumps. Also to be considered is the spring wildflowers such as Bloodroot (Sanguinaria canadensis) and Mayapples (Podophyllum peltatum) will be coming up on this site and we don’t want to accidentally crush them. In light of this, we have fast-tracked our planning and were able to take a day off of work to facilitate this much needed project.