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Flowers of Brush Holly

Juvenile foliage with thorns

Xylosma – Shiny oval leaves

Large tree in flower

Young Flower buds emerging

Large tree with thorns

Grove of large Xylosma Brush Holly

Xylosma conjestum  (Salicaceae)  the Shiny Xylomsa, Brush Holly

On December 16, 2016, while exploring one of the last unexplored areas of Jungle Gardens with Dylan Derouen, where predominately cultivated Camellias and Azaleas abound, we discovered yet another unknown tree.  The first specimen we encountered was juvenile and possessed the most attractive small, ovoid, shiny leaves.  It was heavily armed with long thorns.  Quickly, we found additional young plants and, ultimately in the same area, a large tree.

Later that morning not far from the location of the first plants, we discovered a grove of 12 trees, 10 of which are very large. These trees had considerably larger leaves than the juvenile plants. They also possessed numerous thorns on their new growth and retained very large, branched thorns on the main trunk of the tree.   These large thorns are essentially identical to thorns found on the native Honey Locust tree.  Such large, branched thorns do not occur commonly on large trees, and, therefore, were of great value in the identification of this new discovery.   Using online resources, I was able to determine that the trees were likely either Flacourtia or Xylosma.

These two genera are very closely related.  Both were previously placed in the now defunct family Flacourtiaceae,.  Now they are considered members of the Willow family, Salicaceae.

The larger mature trees did possess a few small, dried-up inflorescences.  They were of no help in the identification process, but at least we knew the trees had previously flowered.

While the type foliage found on these trees suggested they might be deciduous, they are essentially evergreen.  During two successive winter seasons, one of them a harsh winter, the trees never dropped their foliage, despite the literature stating that in freezing weather they may defoliate.

I carefully inspected the grove of trees throughout the following year, hoping to observe them flowering.  All spring I visited the grove and no flowers were ever found; again throughout the summer, no flowers.   In the fall, however, during the last weeks of September I noticed numerous small flower buds appearing along the stems in the leaf axils of every tree.  During the first week of October, 2017, when I visited the grove, every tree had thousands upon thousands of short stalks covered in tiny yellowish green flowers.   The area was filled with the sound of bees.  I would say that every bee on Avery Island was at this grove on the day I first visited.  I collected ample material and returned to Archives to press several specimens and try to finally identify the tree.

As I studied the small flowers using a dissecting scope, I quickly realized that all were staminate (male; pollen producing); none were female.   I returned to the grove the following day and examined the flowers on every tree.  The entire grove had only male flowers.  I went to the first trees we had found, located a short distance from the grove, and those, too, had only male flowers.

With flowering material in hand, I began trying to identity the trees using the online key to the Flora of China.  Much to my dismay, the final couplet in the key does not distinguish between the two genera without the presence of female flowers, of which I had none.

In frustration, I contacted David Bouffard of Harvard University, whose specialty is Flora of China.  I explained my plight, to which he chucked and said, “Just send me a specimen–I will identify it.”

I sent him pressed specimens, and he confirmed the trees as Xylosma conjestum, a Brush Holly.

I continued to observe the grove of Brush Hollies daily.  They were in flower for about seven continuous days, and by the following week no flowers remained on any tree.

Brush Hollies are generally grown and shaped as hedges, not trees.  Adam Black of Peckerwood Gardens in TX, visited Jungle gardens and commented that these were the largest specimens he had ever seen. The largest tree in the grove is 17 inches in diameter all others have a diameter between 11 and 12 inches.  He felt they could be the largest examples of Xylosma congestum in the United States.

History:  This genus contains about one hundred species of evergreen trees and shrubs, found everywhere in the tropics and subtropics except Africa.  When in bloom, Xylosmas attract bees in droves which makes this plant valuable in all types of gardens.

Sagaretia with ripen fruits

Sageretia flowers

Sageretia leaves and flowers.

Bonsai Sageretia

Sageretia thea   Paupers Tea – Chinese Sweet Plum   (Rhamnaceae)

On Oct. 17, 2016, I first saw this peculiar small shrub at the edge of a forested area on Avery Island.  From a short distance I thought it was Privet, Ligustrum sinense, which is widely naturalized throughout all of Louisiana but not common in Jungle Gardens.  This new shrub appeared to have the typical small, opposite leaves that characterize Privet, but upon closer inspection I realized that it was something completely different.  The leaves were more oval, and sub-opposite instead of opposite.  Furthermore, leaf size varied considerably, from very small to somewhat large.  Privet leaves are consistently small.  Despite it being October, I was able to find a few stems with unique small flowers that confirmed this shrub was a species I had never encountered before. 

After collecting fresh material, I returned to the ARCHIVES.  Examining the few flowers I had found, I was able to confirm the family as Rhamnaceae, the Buckthorn Family.  However, it was clearly a member that had never been reported for Louisiana.  I sent photos and, subsequently, specimens to Anthony Reznicek at Ann Arbor, Michigan.  Anthony is the leading authority of the family in the United States.  He identified the plant as Sageretia thea, Paupers Tea, a native of China.  I checked the USDA data base and found that there was only a single previous record of this species for the United States, a collection made in 1989 in Brazoria County TX.  The species was reported as naturalized after cultivation, having spread from where it was planted by the Texas Highway Department. 

In the weeks and months that followed, I found Sageretia growing extensively throughout the forested areas of Avery Island.  In March of the following year, it was observed in flower and fruit in great abundance everywhere on the island.  The small blue-black berries are numerous and have a relatively sweet flavor, like that of a blueberry. There are three large seeds in each tiny fruit.

Sageretia thea has a most peculiar growth habit. This somewhat spiny, evergreen shrub climbs into adjacent trees.  It may reach heights of 30 feet into their canopies, forming a large “bushy” shrub.  I have observed migrating birds feeding extensively on Sageretia berries high up in the canopy of other trees. 

Interestingly, its extensive spread across Avery Island has occurred all within the last 50 years.  The 1966 publication, “A Botanical Study of the Five Islands of Louisiana” by William Reese and John Thieret, failed to record its presence.  There is a reasonable expectation that Jungle Gardens, because of its horticultural nature, was excluded from the field work done by Reese and Thieret.   It is also logical to assume that Sageretia, being of Asian origin, was already growing in Jungle Gardens at that time, but that its colonization of the forest outside the gardens on Avery Island occurred later.

Literature indicates that, in China, Sageretia leaves are gathered from the wild for local use as a tea.  The leaves have also have been shown to have antioxidant activity and contain various medicinally active compounds that are of potential use in the treatment of certain cancers.  

Despite its ungainly appearance, this species appears to be used extensively as a bonsai subject.  Photos of very old bonsaied Sageretia specimens are incredibly beautiful.

Kadsura japonica  (Schisandraceae) 

On September 30, 2016, I noticed a vine growing along the roadside near the end of Holly Hedge Road.  The vine was most notable for its large, dark green leaves and its clambering nature. It sprawled along the ground and climbed and twined on nearby woody plants. While there are many native vines in our area, this one did not match any of the common vines I was familiar with.  I collected a small vegetative sample and returned to the Archives.  I proceeded attempting to identify it using the Woody Plants of Acadiana Flora.  The vine only matched Schisandra glabra, the Bay-Star Vine.

Schisandra is an extremely rare vine found in the eastern United States. Once considered a member of the Magnolia family, it is now classified in its own family, the Schisandraceae. I emailed photos to Charles Allen, who is very familiar with Schisandra.  He agreed the vine resembled Schisandra glabra.

As I continued to explore this area I found more of the vine growing in great abundance, climbing a dead tree in full sun. This habitat is most atypical for our native Schisandra, which never seems to occur in great abundance and normally prefers a dense forest canopy. In the absence of flowers and fruits it was impossible for me to proceed any further with the identification.  However, I remained suspicious of this vine’s true identity.

In early March 2017 Richard Olsen, director of the National Arboretum in Washington, D.C., visited Avery Island.  We spent the day together in Jungle Gardens.  I showed him all of the odd plants I had discovered. When I brought him to the “Schisandra” vine and asked his opinion, he immediately recognized it and said, “That’s Kadsura japonica.”

Kadsura, a native of Japan, is very closely related to Schisandra and is the only other genus in the family Schisandraceae. The discovery that this vine was not Schisandra, but in the same family, was more exciting to me than if it had been our native Bay-Star Vine.  It meant that E. A. McIlhenny had planted this vine in Jungle Gardens no less than 70 years earlier, and it has survived and thrived all on its own with no human attention.

The Kadsura vines are scattered primarily along the south side at the end of Holly Hedge Road.  There is one large mass of vines growing in full sun and numerous small separate plants growing nearby in dense shade on both sides of the road, some distance apart. The presence of these individual plants in the immediate vicinity of the massive Kadsura growth suggests its spread could be the result of seed dispersal.  Alternatively, given the length of time the population of Kadsura has been at this location, its spread could also be the result of long-term vegetative growth.

On August 8, 2017, while exploring the location with Herbert Levitt, he discovered a vine with flowers. A small pendant vine on a holly tree had numerous small, yellow, axillary flowers. We searched for and found several additional vines in the immediate vicinity with flowers.  All flowers observed were identical.

Kadsura plants are always unisexual, producing either male or female flowers but never both on the same vine.  I feared that the entire population might all be descended from a single introduced plant and thus be unable to produce fruits and seeds.

At that time I thought the flowers we found were staminate, essentially “male,” but now, one year later, I realize they were all pistillate “female” flowers.  None were staminate.

On June 19, 2018, I was again visiting the Kadsura locality with Shane Bernard and found several different vines with flowers. These flowers were noticeably unlike those we had found the previous year.  This time I could tell these were staminate flowers.  Now I knew both sexes were present in the population.

Therefore, there is hope that both male and female plants could be found growing in close proximity, increasing the chances that fruit and seeds could be produced.

The very next day, June 20, 2018, Leigh Simmons and I returned to photograph the flowers. We ventured across the road where I had previously found a small group of vines growing.  Much to our delight we observed many flowers at this location, and it was immediately noticeable that the flowers were of two types.  We collected several and brought them back to ARCHIVES for closer examination.  Using a microscope, I was able to determine that we had found both male and female flowers at this one location.

I revisited the Kadsura location during the second week of July 2018 and found an abundance of mature flowers on many vines on both sides of the roadway. This time I could clearly see flowers of both sexes, present in areas where I had previously only observed a single sex.

Now we patiently wait to see if any fruits with seeds will be produced.

Rhamnus utilis, (Rhamnaceae)

On September 30th 2016, while exploring Jungle Gardens, I found two unusual small trees growing along the edge of the forest on the hill above Buddha. The leaf shape, venation and bright green color caught my attention from some distance away. Initially I thought it could be one of several native Louisiana trees. I made a small collection of the foliage and tried to match it to similar specimens at the UL Herbarium. It did not match any of the native plants I thought it could have been. This was a tree I had never encountered before.

The next day I returned and photographed living material and sent the photos to Eugene Woffard at the Univ. of TN Knoxville. He thought it could be a species of introduced buckthorn, Rhamnus and suggested I contact Anthony Reznicek.  “Tony” from the Univ. of Michigan, Ann Arbor is regarded as US expert on the Rhamnaceae. I emailed photos to him and he agreed it looked as though it could be one of several introduced Buckthorn species.  He would need reproductive material to make a final determination.  The following spring on March 29th 2017 one of the two trees was in flower.  All along the young branches in leaf axils were dense clusters of small yellow-green flowers. I took photographs and made several herbarium specimens.  A specimen was sent Reznicek in Ann Arbor. Upon receipt he confirmed that the mystery plant was the Chinese Buckthorn, Rhamnus utilis.

Chinese buckthorn is a spiny shrub or small tree, typically growing to 4 m (12 feet) tall. It is native to China, Japan, and Korea. It has been introduced to the US and its known distribution includes, IA, IL, IN, MI and CT.   It is not known to occur in any state south of that group of central states.  Its presence in Louisiana represents a significant disjunct  distribution for the species.

It seems unlikely that the Jungle Gardens, Avery Island location for Rhamnus utilis is due to long distance dispersal, considering the absence of the tree in all other states between Iowa and Louisiana.  Due to the extensive introduction of Asiatic species in Jungle Gardens, I am inclined to believe that these two trees represent plants persisting or spreading after cultivation from introductions planted long ago.   I have carefully monitored both trees during two flowering seasons, spring 2017 and 2018.  The trees produce flowers in great abundance but all have failed to yield even a single fruit.   The complete absence of fruits with seeds would certainly account for the rarity of this species in Jungle Gardens.   It is said to be an “insidious species” where it has become established in other regions of the US so its inability to reproduced well in south Louisiana may be a blessing.

Continue reading “Chinese Buckthorn – Rhamnus utilis”