Solomon's Seal (Polygonatum biflorum)

The arrestingly-named Solomon's seal (Polygonatum biflorum) is a handsome herbaceous plant. Its obscure common name is well-paired with its genus name, Polygonatum (which comes from the Greek gonatos)  and means "many-kneed." Do plants have knees? What does all this mean? We won't dwell on the unanswerable. There are a few dozen species in the genus, but most find their home in East Asia, far from Caddo Parish, Louisiana. 

As far as names go, we have a problem; our current signage turns out to be inaccurate. The arboretum catalogue shows two collection dates for hairy Solomon's seal (Polygonatum pubescens), both dating from the '90s. In 1991, Professor Ed Leuck collected a few plants from within Shreveport's city limits, on Line Avenue. A healthy patch still grows under the origianl red buckeye plants. In 1996 Jack Price of Blanchard donated six pots. Those plants have thrived on the southwest side of the long wooden bridge that runs from the Student Union Building to Mickle Hall. This patch continues to grow out into the lawn. Plants were collected from the grassy area and then transplanted to other areas of the arboretum, resulting in two additional patches of Solomon's seal. So, there are four total patches of Solomon's seal, and the original two patches are marked with green signs that read 'Solomon seal (Polygonatum pubescens)'. 

This is a relatively new patch of Solomon's seal. In 2023, we relocated a couple of plants to this spot, alongside a young black cherry (Prunus serotina). The black cherry has since grown tall, shading the Solomon seal.

The fruits were noticed several weeks ago. 

Leaves alternate and have noticeable ridges or veins.

As the bell-like flowers of Solomon's seal descended daintily and prettily from the stalks, so now do the berries.

These fruits greatly resemble blueberries, although they are much more firm. Be careful! NC State Extension claims, "The berries, if eaten, are poisonous."

Dark blue round fruits measure less than ½ inch across.

 

Squeezing the large fruit opens the bright green interior, revealing numerous seeds. Seven seeds came from one fruit. Another yielded four seeds.

 

Looking at the current classification information for Polygonatum in the United States shows P. pubescens and P. biflorum are the two major species east of the Mississippi. However, a distribution map clearly shows that P. pubescens is not found in the Deep South; its homelands begin in the mountainous, cooler climates of Kentucky and Tennessee. Since the distribution map for P. biflorum makes much more sense in covering the entire eastern half of the USA, we needed to take a closer look at the plants currently growing in the arboretum.  

Descriptions for both species state the fruits are similar. Descriptions differ for flowers, leaf size and shape, and the presence of hairs. Since flowers aren't available in late summer, all four patches of Solomon's seal were studied for leaf size and shape and the presence of hairs. 

This egg-shaped leaf suggests P. biflorum.

These narrower, lanceolate-shaped leaves suggest P. pubescens. 

These leaves are from two different patches. Do we have two different species or different light-conditions? The top leaf was found in full-shade. The bottom leaf was found in partial shade.

 

 

Within the arboretum's collection, leaf size and shape suggest that we have two different species of Solomon's seal. However, the common names dwell on the presence of leaf hairs, and although the leaves varied in size and shape, no hairs were seen on any stems or leaves. All surfaces felt and looked smooth. 

This is the underside of the leaf. We see spots, but nothing fuzzy. 

The underside is smooth. Leaves and stems from all four patches were examined, and nothing resembling hairs was detected. 

Based on species distribution and the total absence of hairs, we shall change the arboretum catalogue to note that we have Polygonatum biflorum, rather than Polygonatum pubescens. And, in the spring, we must study the flowers to see if they can give us any other clue as to the correct species label.

 

 

For more information about this species, please consult the following online sources:

USDA Plant Database Info for Smooth Solomon's Seal

USDA Plant Database Info for Hairy Solomon's Seal

Flora of North America Species comparison for these two plants 

Plants of Louisiana

NC State Extension 

Spice Bush (Lindera benzoin)

Spice bush (Lindera benzoin) fruits are ripening in northwest Louisiana. The youngest spice bush in the arboretum collection has a surprising number of fruits.

 

In 2022, this spice bush volunteered among a grouping of fringe trees (Chionanthus virginicus). This photo was taken the following summer in 2023. At that time, this spice "bush" had one primary stem, suggesting that it might develop a tree habit.

 

Today, the spice bush looks decidedly more like a 'bush' than a small tree. In this photo, we see several distinct stems.

 

Our young spice bush is tagged. Not every entry in the arboretum catalogue has a sign―that would be too much clutter in the landscape. There are already two spice bush shrubs with signs in the arboretum.

 

Numerous fruits are hiding among the leaves.

Sitting *under* the shrub, it's much easier to see the fruits.

Fruits appear in clusters along the branch.

The bright red fruits are ⅜ inches long. According to North Carolina State Extension, the fruits are edible.

The large, green drooping leaves come to a point and the leaf-base is asymmetrical. Both leaf and fruit have a spicy fragrance.

Kentucky Coffee-Tree (Gymnocladus dioica)

In our contemporary situation of free and easy global trade, yearly consumption of coffee beans amounts to almost 25 billion pounds. You can get a cup almost anywhere, anytime. But since Coffea arabica can only be grown in a relatively few environments, war or trade embargoes can easily cut off coffee supplies to most places on earth. Due to this problem and the recognized benefits of the drink, coffee substitutes have often been sought and utilized. Today we'll showcase the arboretum's Kentucky coffee-tree (Gymnocladus dioica). 

 

It isn't native to Louisiana. The map below shows that the plant is really a Midwestern fellow, with its distribution dipping down into the southeast. 

This map shows the current distribution according to the USDA-NRCS. The Kentucky coffee-tree (Gymnocladus dioica) does not typically grow in Louisiana. Since it can be found in central Arkansas, this species certainly deserves representation in the Centenary arboretum.

There are two Kentucky coffee-trees growing in the arboretum. There is a big one, and right next to its trunk, there is a little one, which is clearly waiting for one of the surrounding trees to die so that it might have a chance to grow. These two trees do not have an official entry in the arboretum catalogue. They are mentioned elsewhere, in regards to other plants, but their specific planting history is missing. In an entry for spiderwort, the Kentucky coffee-tree is mentioned: "Another large clump [of spiderwort] with the seedling Gymnocladus dioica, below iris bed in west floodplain, planted 1999." A Kentucky coffee-tree seedling was growing in a pot with spiderwort, and they were planted together in the west floodplain in 1999. So, the Kentucky coffee-tree is at minimum 25 years old. According to the Iowa University Agriculture and Natural Resources Extension, the tree should be sexually mature and fruit-bearing once aged 20-30 years. Interestingly, this tree came to our attention this week because we found an unusual seed pod in the leaf litter.

This seedpod was found in the west floodplain under the Kentucky coffee-tree. Since the species is dioecious, that means our tree is female, but where is the male? How was it fertilized? The pod was cracked open and one seed was removed. It was in poor condition, so it was discarded.

Two more fruits were found. One is significantly larger.

The larger pod has one seed.

It's a large seed, mearsuing approximately one inch across.

The seed is round and dark brown.

As with the Yapuon holly (Ilex vomitoria), the Native American Indians of the Southeastern Woodlands are reputed to have consumed a tea made from the seeds of Gymnocladus dioica. The paucity of consumer goods in colonial times, being a major issues for homesteaders and travelers, there has been interest in this tree's seed since at least the late 18th century. Some people employed the Kentucky Coffee-Tree as a coffee-substitute up to and possibly during the American Civil War, when a Union blockade cut off the Confederate States of America from international trade. It was greatly inferior to the alternatives, such as chicory and scorched barley, as an uncaffeinated coffee substitute. Experiments performed by John P. Spaeth and John W. Thieret in the earlier 2000s showed that although potable, this drink was generally squalid. While true coffee addicts would consider such a product little better than a criminal act, a hot herbal beverage is better than nothing on cold days and long nights. Let's now check out the specimen itself.

The Kentucky coffee-tree is pictured center. It grows in a heavily shaded floodplain. All lower branches have been removed, so it will easily be missed as "just another tree" unless one is looking for it.

The wish-bone shape of this tree is no doubt a response to growing in heavily-shaded conditions. This tree is clearly adaptable.

It was planted near a Pinus taeda, an on-site native. From its first planting in the arboretum, the Kentucky coffee-tree has had to compete for sunlight, leaning away from the looming pine tree. Alas, it's good to have friends, even if you have to share your place in the sun. These trees have known each other for a long time.

The photos below were taken during the winter months. They allow us a less-cluttered view of the landscape.

 Clumps of spiderwort (Tradescantia ohiensis) grow at the base of the Kentucky coffee-tree trunk. Spiderwort was planted at the same time as the coffee-tree.

Kentucky coffee-tree has gorgeous papery bark.

 

The tree has an irregular growth pattern, as noted above. Hopefully this will not lead to cracking and breaking in the future.

Additional resources:

USDA Plant Profile on Kentucky Coffee-Tree

Lady Bird Johnson Wildflower Center

North Caroline Gardner Extension 

Chinese Privet (Ligustrum sinense)

Let's take a moment to reflect on plants' names. Some are very straightforward: red oak, white oak. Others, such as salt matrimony vine, are, to say the least, a bit complicated. But what, exactly, is meant by the simple name Privet? Many sources agree that the plant has an unfavorable odor. It is variously described as resembling rotting hay or having a sickly sweet smell. Does the name Privet derive from the old-fashioned word "privy," referring to an outhouse? When in doubt, consult the 1933 edition of the Oxford English Dictionary, which contains etymologies and early appearances for its entries. From William Turner's 1548 Names of Herbes: "Ligustrum is called in greek Cypros, in englishe Prim Print or Priuet [privet]." Unfortunately this citation doesn't tell us what Privet means, and the extra information only adds additional question marks. Let's move on quickly....

Privet has a lot going for it; this plant is resilient, vigorous, and fertile. To our detriment, it is not native to the southeastern United States, having originally been imported from East Asia in the mid-1850s. Privet has been taking over real estate from our native species since it went feral in the first half of the 20th century. Conservationists have been unable to roll back its rapid colonization of the backcountry. If you're the kind of driver that takes your eyes off the road then you've definitely seen large stands of this invasive species along the interstates and highways.

Privet has thrived in our volunteer recruitment zone. Because of its non-native status, it was easy making the decision to remove privet from this area.

 

This is our volunteer recruitment zone. In our last post, we discussed the removel of groundsel (Baccharis halimifolia), and this week we are cutting down all of the privet (Ligustrum sinense). From this angle, we still can't tell that much has been removed.

This is a collection of privet shrubs removed from the volunteer recruitment zone. The tallest privet measured was nine feet in length. While it may reach twenty feet or taller, most full-grown privet measure between five and fifteen feet. Ours had probably reached its limit given the available sunlight.

Leaves are opposite, oval, and a thoroughly flat green.

Our privet twig shows variation in leaf size.

We see some leaf shape variation. One of the those leaves looks almost like a circle.

So long privet shrubs! Next week, we hope to further reduce the wildness of our volunteer recruitment zone, and perhaps we will choose an individual or two to add to the permanent collection.

 

For additional information about privet, please see the following three articles from the LSU AG Center:

Chinese Privet

Dealing with Privet 

Privet, A biological invader in Louisiana's Forests 

Groundsel Shrub (Baccharis halimifolia)

Work is officially underway to reduce the wildness of the arboretum's volunteer recruitment zone. You can read about this special area on a previous blog post, found here. It can be difficult deciding which plants get to stay and which plants must go. However, given the specific site attributes, some species won't do well here in the long term. This is a shady, uphill area; not a good place to showcase wetland species. As horticulturists and gardeners eventually learn, allowing plants to grow up in a bad location may create unnecessary work down the line, as they still grow large enough to create a big mess when they eventually succumb. Therefore, it was an easy decision to begin the removal of groundsel (Baccharis halimifolia), a shrub that grows profusely along waterways.

The volunteer recruitment zone is home to groundsel, which is no surprise given its regional status as a highly successful colonizer.

Many different unrelated species of plants are called "groundsel," but that name most commonly indicates Baccharis halimifolia.  The groundsel bush is a dioecious, decidious shrub native to the Southeast, from the gulf coast to the mid-atlantic states. Tolerant of both drought & wet locations, rarely browsed by animals, groundsel can form monotonous stands that prohibit the development of other worthwhile species. It is however a major food source for bees and other flying insects during its flowering season.

Groundsel leaves alternate along the stem.

Alternating leaves

This fresh green leaf is noticeably slender and toothed.

Upper leaves are strongly oval-shaped.

Here we can see leaf shape variation.

Lower leaves are rounder, but still show the same "coarse teeth" and smooth texture of the upper leaves.

The bark is striated, with vertical bands of green, grey, and brown. This is young bark; at most, this shrub is four years old.

 

We removed all the tall groundsel shrubs from the volunteer recruitment area. The tallest shrub measured nearly 9 feet. Some of the small to medium size clumps were cut as well, simply because they were visible. This is a hefty amount of green material.

 

 

This photo was taken before the groundsel was removed.

Our mini-wilderness area is still thick with plant life; this is a photo after the groundsel was removed. Not much changed. It's difficult to tell that anything is missing.

 

 

Groundsel is notoriously resilient, so don't worry; even with this culling it'll be back soon. However, this particular location in the arboretum isn't ideal for groundsel: we want to see it in wetter locations. We might try relocating small plants to sunny areas near the drainage channels.

See our previous posts which contain photos (credit to Bonnie Bernard) of groundsel, from January 2012 and March 2012. That's a long time ago! You can also see one of our groundsels covered in this sweetgum post from 2021.

Links:

USGS Plant ID

LSU AG Center

USDA NCRS