Balloonvine (Cardiospermum halicacabum)

Whenever your arboretum curator is on a nature walk, she is always on the lookout for uncommon native species and unknown plants. Recently such a case occurred when we spotted a cluster of small, brown papery husks in some damp undergrowth. Upon inspection these were the fruit of a ground-trailing vine with parsley-like leaves. 

 

These seed pods draw the eye, as they look quite strange and unnatural.

 

 

The leaves are distinctly parsley-like or cilantro-like.

Each fruit was a capsule made up of three separately inflated lobes, each of which contained a single seed. The seeds are spherical and mostly black with a single a round, cordate, or fabiform white marking. Immature fruit were papery but green instead of brown, with green seeds instead of black & white. Upon consultation of the literature, we first believed this to be Cardiospermum halicacabum, the Balloonvine or Heart-seed. The first name explains itself, while the second refers to how the white spot can resemble a heart. This curious plant is a member of the Soapberry family (Sapindaceae). It likes wet areas and is able to colonize disturbed and marginal environments.

The proper domain of this species is a bit confused. Found across the subtropical and tropical regions of the globe, this plant is native to Mexico, the Caribbean, northern South America, sub-Saharan Africa, and subtropical Asia from India to Melanesia.

 

Current distribution of Balloonvine in the Southeast, according to the USDA-NRCS

 

Guy L. Nesom, in his 2009 article Assessment of invasiveness and ecological impact in non-native plants of Texas categorized this species as "F2:Abundant in number and widespread, commonly invasive in disturbed habitats, much less commonly in natural habitats; subdivided into woody, herbaceous, and aquatic species."

Nor is it much appreciated where it appears. Consider the US state of Georgia, in which "It is unlawful to sell, offer for sale, or expose for sale any agricultural or vegetable seed" contaminated with forty named species. Thirty are restricted, allowing only a certain number of those species seeds per pound of agricultural seed. The same is true in the state of Louisiana: Balloonvine is entirely prohibited. Even a single seed cannot be mixed in with agricultural seed without incurring a violation. This is particularly a problem with soybeans because the seeds of Balloonvine can closely resemble a soybean, although the average Cardiospermum halicacabum seed is only as large as the smallest soybean.

Is it all bad? No. The European Agency for the Evaluation of Medicinal Products has written that extracts of Cardiospermum halicacabum have legitimate veterinary and hygienic uses, given that it contains anti-inflammatory properties and is insecticidal and anti-bacterial. 

Cardiospermum is taxonomic Latin for "heart-seed," but something is funny here. I'm not seeing any hearts. These are Lunaspermum or Demispermum at best. Is there some significance to the lack of hearts? Is this normal variation within the species or should we be uncertain about the identification?

Compare with this image, courtesy of fairdinkumseeds.com. There's quite a difference; these seeds have a distinctive heart-shaped white spot.

Back to ours. The left-most seed has been sliced in half, revealing that an opaque milky-white endosperm layer rests within the black-and-white seed coat.

 Upon further reflection, we are not sure what we've got on our hands. These seeds lack the distinctive heart-shaped white marking. It very well could be another member of the genus Cardiospermum, and even be a species native to the Southern US, if not our local area. But how can we tell? Consider this opinion from the North American Butterfly Association's page on Cardiospermum corindum: "Confusingly, all five of the vines are often referred to as ‘balloon vine’ or ‘heartseed’. Frustratingly, there seems to be mixed opinions as to the native status of the various balloon vines." You can say that again.

Twice above we've mentioned that this plant has parsley-like leaves. Cardiospermum corindum, the likliest candidate for this specimen after Cardiospermum halicacabum, has the common name of Faux persil. Persil is the French name for the culinary herb parsley, which ultimately derives from the ancient Greek "petros" meaning stone and "selinon" meaning celery.

Unfortunately photos of this genus online are in a very disordered state. It's just not possible to decide on what we're looking at. Due to the ambiguous nature of this plant, we won't transfer it to the arboretum. But if we find some growing there, we won't pull it up, either. It's not much of a leap from Mexico or the Caribbean to Caddo parish, and if this species finds a home here, that's fine with us.

Invasive Plant Atlas page on Balloonvine

Dr. Robyn Burnham's page on Balloonvine 

Tree Removal: Pawpaw, Sweetgum, Mulberry

Today we continued normal cleanup operations in the Arboretum. This customarily involves cleaning up the paths, picking up fallen limbs, moving gravel around, and today a special task: cutting down some trees and removing stumps.

First, a water leak in the arboretum, down the slope from Mickle Hall, required a lot of dirt work. This area is in shambles, but there is really no alternative. Our native clay can be quite an adversary. Don't try to walk through this area; just go around.

Onto the main tasks.... Here is a sweetgum (Liquidambar styraciflua) stump, which you can see on an earlier blogpost here. In that post we said "Now all that remains is a two-foot stump which will be removed at a later date." That day has arrived.

Resprouting, this tree is still alive. This photo was taken after all of the new growth was trimmed.

Afterwards, we have a more-or-less flat area that will not be a tripping hazard. The roots were not removed, which means that we have not yet seen the end of sweetgum shoots.

Next we have a highly suspect pawpaw (Asimina triloba), which you can read more about on an earlier blog post, here. This tree has had a broken crown for nearly a decade, which may have led to some health problems. Recently it has taken a turn for the worst, so now we must make an assessment. Before we cut the tree down, let's inspect the specimen to determine its condition.

 

The bare pawpaw trunk is pictured center. Louisiana palmettos and titi shrubs are in the background.

This image becomes more unsettling the longer you look at it. Here you can see fungal pink slime oozing from the bark and forming bubbles. What on earth is this?

This rotten branch nub was characteristic of the whole tree.

Scoring thin bark will often reveal healthy green cambium underneath. Scoring this pawpaw revealed dead tissue and only excited the ants and other bugs crawling across it. Snapping a few twigs, which should have been green and springy, verified that this tree is completely dead. Cutting it down released a horrendous mushroom-like smell.

All gone, and only a few blog posts to tell the tale.

This cross section reveals a rotten tree. It may not be immediately obvious from this photo, but the inner rings of the tree were sickly green and oozed.

The lower feet of the trunk served as a nursery for untold billions of fungal spores and the entire surface of the bark had turned green. The white specks were tubular filaments rising off the surface of the bark and ending in a nodule.

Finally, this undesirable specimen is a hybrid of Morus rubra, the red mulberry, and an Asian species. Since we want to preserve native species, we will remove this one as we have removed other white-berried and black-berried mulberries in the arboretum.

We see leaves of the characteristically variable Morus genus.

Our mulberry hybrid was dissassembled.

This area is already a major tripping hazard due to holes and uneven ground, so we've sawed the stump down as low as possible. Cutting around soil will quickly dull your chainsaw blade, but there's no helping it.

Autumn is a great time of the year for these kinds of clean-up operations. Look around and you'll find plenty of work to do!

Education & Outreach

An academic arboretum has two purposes. In its fundamental and most basic role, such an institution serves as a repository for living specimens and the germplasm of plant species. If this goal has been accomplished, a secondary role can be achieved: showcasing these specimens to students and the public, with the intention of increasing knowledge about those trees, shrubs, and herbs. Because they exist in physical space and not as a description in a book or on a computer, the arboretum's cataloged specimens can be seen year-round and from 360 degrees. You can "zoom in" and look as close as you want. Can't find just the right photo of a tree? Go snap one yourself at the arboretum. If you like the organism enough, you may be able to collect some seed and start your own. Short of cutting the specimen down or doing permanent damage, every plant in the arboretum is part of an interactive experience; no screens involved.

In support of this ideal, today we'll show some photos of a recent arboretum tour that Centenary College's Visual Identity and Publications Manager Sherry Heflin was kind enough to photograph. Normally, photos of tours given at the arboretum are not available, since the curator cannot photograph herself while thinking, walking, and speaking. Perhaps the arboretum needs a very expensive autonomous drone with a nice lens for such occasions. Then again, Skynet drones might disrupt the ambience for a group that is supposed to be experiencing nature. 

 All photos below were taken by Sherry Heflin, on October 21, 2024.

The tour began in the oldest part of the arboretum, between Hamilton Hall and the Student Union Building. One of the four black metal arboretum signs marks the northern edge of the arboretum.

For a tour during the fall, fruits are a great topic. The arboretum has many different species of oaks growing in a small area, so it's easy to find acorns and compare them. These small acorns were collected under a water oak (Quercus nigra).

This big acorn was snipped from a Burr oak (Quercus macrocarpa).

Persimmons are ripe this time of year! Here, the arboretum curator holds an example of a perfectly ripe persimmon (Diospyros virginiana).

French mulberry fruits are also edible, but not recommended. These pretty purple fruits weren't as numerous in late October.

The arboretum curator displays the very small seeds of the redbud (Cercis canadensis).

In the arboretum, there are plenty of opportunities to play the game: 'Where's the tree? Where's the vine?'. Here, the arboretum curator points out bright red fruits hanging from a black cherry (Prunus serotina). The bright red fruits actually belong to a vine, Carolina moonseed (Cocculus carolinus).

Ouch! These spiny fruits were produced by the American chestnut hybrid, Dunstan (Castanea dentata).

The arboretum has numerous red buckeyes trees (Aesculus pavia). Here, a Centenary students opens a buckeye fruit, looking for the large seeds.

Buckeye seeds are shiny and look oily. What do you think they smell like?

Competition over resources wasn't the focus of this tour, but a few examples were pointed out. Here we have an interesting example. Two trees are shown here. Their trunks have grown together. The slender trunk, leaning toward the left, belongs to a black oak (Quercus velutina). It was intentionally planted. The big trunk, growing straight up, belongs to a southern red oak (Quercus falcata). The red oak volunteered a few years after the black oak was planted, and the red oak has out-competed the black oak for sunshine, water and nutrients.

Even what looks like a bare stick is worth talking about. At the beginning of the tour, the arboretum curator explains that these is the arboretum's original patch of Hercules-club (Aralia spinosa), planted in the old part of the arboretum, circa 1990. Only three spindly plants remain.

Later in the tour, the arboretum curator points out a thriving grouping of Hercules-club. Here, the curator stands among the Hercules-clubs, holding two trunks. These plants are younger, and yet they are significantly larger. Viewing these plants in person and walking through the landscape, we can easily start to formulate hypotheses.

There is always something to talk about in the arboretum. The landscape is always changing!

Chinese Tallow Tree (Triadica sebifera)

In this post we'll discuss the Chinese tallow tree (Triadica sebifera), a "spurge" in the family Euphorbiaceae. Spurge is a funny-sounding word, but is merely an archaic English word related to "purge" or "expurgate," referring to the latex that many spurges, including the Rubber tree (Hevea brasiliensis), contain. Do not mistake the Chinese tallow tree for the Chinaberry tree (Melia azedarach), a member of the mahogany/neem family. If you did so, you would easily be forgiven since they have many similar characteristics:

• Both trees are native to East Asia, although the Chinaberry tree has a much wider distribution from India to China to the Indonesian archipelago.
• Both trees were brought to the American Southeast around two hundred years ago, where they quickly went feral.
• Both trees have some ornamental applications and some productive uses, but these positives are outweighed by the toxicity and sheer weediness of the plants.

The arboretum does not contain Chinaberry trees, as far as we know. We do have volunteer Chinese tallow saplings. They germinated in one of our wild areas and had the opportunity to grow unhindered for more than two years. This past week, the tallest and most conspicuous individuals were removed.

There is a small, overgrown area of the arboretum at the southwest corner of Mickle Hall. It was mowed only once within the past three years.

This area slopes down toward the arboretum drainage channel. The groundcover was badly damaged and the topsoil was washed away during the Mickle Hall rennovations that occured in 2011. The groundcover never recovered and consequently the area was progressively eroded, so we decided to stop cutting this area in the hopes that something would take root and keep the soil in place.

Chinese tallow tree (Triadica sebifera) was one of many voluteers that unexpectedly took root in this difficult space. In this photo, the Chinese tallow tree has grown up above the surrounding grasses and is leaning toward the sidewalk, stretching for more sunlight.

Chinese tallow tree has a very distinctive leaf shape. It looks like a Christmas decoration!

The tip of the leaf comes to a point.

This is a small bundle of young Chinese tallow trees. They were all removed from the same area. Since there aren't any mature Chinese tallow trees in the arboretum, it would be interesting to know where the nearest mature specimen is located.

This is the slender trunk of one sapling. The leaf petioles alternate up the trunk.

Chinese tallow leaves are very pretty. A fly photobombed the picture, giving us a great size-comparison photo.

External links:

USDA page on Chinese Tallow Tree

LSU AG Center page on Chinese Tallow Tree 

LSU AG Center page on Chinaberry Tree

N.C. Cooperative Extension page on Chinese Tallow Tree

Poison Ivy (Toxicodendron radicans)

Poison ivy (Toxicodendron radicans) is robust, shade-tolerant, and manifests in multiple distinct growth-patterns. It's found almost everywhere in the Eastern woodlands and offers food for birds with its berries, although it can also spread asexually. These traits make it an important and resilient plant species, adding to its reputation as a fearsome nuisance.

The most salient aspect of poison ivy is the resin found in its leaves: urushiol. This term derives from the Japanese name for a related species, Toxicodendron vernicifluum, the Chinese lacquer tree. Not confined to poison ivy, urushiol resin can be found in many members of the family Anacardiaceae, which also contains the sumacs (genus Rhus) and the cashews (genus Anacardium). Despite its traditional use in East Asian arts and crafts as the primary ingredient for lacquerware decoration in woodworking, urushiol is a potentially dangerous poison. Contact with the resin leads to an immune-response whereby the skin is attacked by the afflicted's own T-cells. Rash, blisters, scarring, and even necrosis in severe cases results, and a prolonged healing period is generally required before the affected skin returns to normal.

Thankfully, not everyone experiences an allergic reaction after exposure. Even within nuclear families, one member will be allergic and another may be immune or only slightly allergic. For those who do "take poison ivy rash," knowing how to identify this plant is extremely important if you like to be outside. This plant isn't just found in the woods; it grows readily in town, and it frequently germinates in the arboretum as a volunteer; thanks, birds. Although it isn't welcome in the landscape, we never get rid of all of it.

 

This is one of the arboretum's less-cultivated areas. It's a small wedge-shaped zone located near the southwest corner of Mickle Hall. Due to a serious problem of erosion in this section, we have allowed some extra undergrowth to accumulate that would not be tolerated elsewhere. Over the last approximately three years it has only been mowed once.

A couple of poison ivy plants were spotted this week. Two vines were growing straight up, and they had grown taller than the surrounding plants, making themselves conspicuous. The Japanese proverb Derukui Wautareru (The nail that stands up gets hammered down) is appropriate here, given the urushiol. Let the rest of the arboretum's denizens be thus warned.

This is the tallest vine that was snipped. Several additional pieces were carefully cut, photographed and then discarded.

 

This is a detail image of the vine. Here we see light green leaf stems alternating along a light-brown vine.

 

Poison ivy has compound leaves. In this photo, we see one leaf. Each leaf has three leaflets. Some people find the saying "Leaves of three, let it be" helpful; other people find such expressions confusing.

 

This is another leaf. There are three leaflets, and one leaflet shows signs of predation. Who out there is bold enough to chow down on poison ivy?

 

USDA page on Poison Ivy

LSUAgCenter page on Poison Ivy ID 

Urushiol and lacquerware 

Toad's World

What secrets do these sprinkler boxes hold?

Amphibians! To the novice, these may appear to be "frogs" or even "toad-frogs." In fact, they are true toads of the family Bufonidae. This is either eastern toad (Anaxyrus americanus), southern toad (Anaxyrus terrestris), or Fowler's toad (Anaxyrus fowleri), three closely related species occuring in our region. We'll call this a medium-sized specimen.

Now for the itty bitty, insy winsy variety: this little fellow looks like he was born yesterday. But give him some credit; he is probably the sole survivor of a clutch of thousands of eggs. Given these odds, we should award these little fellers some credit. Like the medium-sized specimen above, we can't tell if this is an American, Southern, or Fowler's toad.

Seen in profile, this small toad has good posture.

A comparison is a nice way to round out this post. Clearly we have enough bugs and creepy crawlies to go around.

These toads come in red, black, brown, tan, "Mossy Oak," and all the shades in-between. Examination of the links below has led us to believe that this is a Fowler's toad (Anaxyrus fowleri). Identification mostly depends on the presence and form of ridges between the eye socket and neck glands, as well as the relative size of leg warts. In this case, the specimen lacks a prominent post-orbital ridge and has more-or-less uniformly sized warts. Let's also take a moment to mention that toads are not only gorgeous creatures, they are seasonally appropriate.

Do you remember the line "Double, double toil and trouble; Fire burn, and cauldron bubble" from Macbeth? You may have forgotten that in the long list of ingredients, TOADS were the first reagent to be added:

Round about the cauldron go;

In the poisoned entrails throw.

Toad, that under cold stone 

Days and nights has thirty-one 

Sweltered venom sleeping got, 

Boil thou first i’ th’ charmèd pot.

Fillet of a fenny snake

In the cauldron boil and bake.

Eye of newt and toe of frog,

Wool of bat and tongue of dog,

Adder’s fork and blindworm’s sting,

Lizard’s leg and howlet’s wing,

For a charm of powerful trouble,

Like a hell-broth boil and bubble.

Scale of dragon, tooth of wolf,

Witch’s mummy, maw and gulf

Of the ravined salt-sea shark,

Root of hemlock digged i’ th’ dark,

Liver of blaspheming Jew,

Gall of goat and slips of yew

Slivered in the moon’s eclipse,

Nose of Turk and Tartar’s lips, 

Finger of birth-strangled babe

Ditch-delivered by a drab,

Make the gruel thick and slab.

Add thereto a tiger’s chaudron

For th’ ingredience of our cauldron.

External links from Gonefroggin':
Fowler's Toad
Southern Toad

Photos of Fowler's toad from UC Berkley

Photos of Southern toad from UC Berkley

A helpful youtube video on toad identification