Chinese Sweet Gum – Liquidambar formosana

 

 

 

Liquidambar formosana,  Asian Sweet Gum,   Formosa Gum

Liquidambar formosana, commonly known as the Chinese sweet gum or Formosan gum, is a tree native to Eastern Asia.  There are two very large examples of this species growing side by side in Jungle Gardens.  The tree’s distinctive leaves are three-lobed, unlike the five to seven lobed leaves of the North American species, L. styraciflua.  The foliage of L. formosana turns an attractive red and yellow in autumn.  In its native Eastern Asia, the leaves are used to feed silk worms, and the wood is highly prized for making tea chests.

The individual flowers of L. formosana are monoecious (unisexual), but both male and female flowers can be found on the same plant.  Male flowers are in long, pendant catkins, whereas female flowers form dense, spherical heads, known as ‘gum balls.’  The fruits are burr-like because of the persistent female floral structures known as ‘styles.’

Although Liquidambar formosana is uncommon in cultivation,  I have seen it growing at the New York Botanical Garden and similar gardens in the Eastern United States, so it has a wide range of growing zones.

The two trees in Jungle Gardens flower every year and produce many gum balls, but I have not observed any seedlings in their vicinity.  I estimate the trees to be in excess of 80 years old, they are 24.5 and 22.5 inches in diameter.

I will never underestimate the value of exploring for trees in fall months when most are in some stage of dropping their foliage.  On December 16,  2017, while exploring a wooded ravine near the Old Nursery in Jungle Gardens with tree expert Adam Black of Peckerwood Gardens in TX, we discovered two trees that initially we identified as L. formosana.  Both trees, one in the ravine bottom, the other on the crest of the ravine, are 5.25 inches in diameter, suggesting they are the same age.  We first observed fallen leaves.  Their bright yellow color and unmistakable three-lobed leaves left little to the imagination as to their identity.   Two days later I returned to collect some of these leaves to make a voucher specimen.  Both trees had lost most of their foliage; the few leaves that remained on the trees were so high up that none were within reach.  As I collected leaves from the ground below the tree I quickly noticed the variable number of lobes.  Many leaves had the standard three lobes, but some were asymmetrical with four lobes and others had five lobes.  My collection contained an assortment of leaves from each tree that had an inconsistent number of lobes.  I immediately became suspicious that these two trees were not L. formosana but more likely hybrids with our native Sweet Gum species.

Returning to Archives with the leaves, I photographed, pressed and dried them.  A few days later I emailed the photos to Richard Olsen of the US National Arboretum.  He immediately confirmed that the trees were hybrids between the two species.  He went on to say that such hybrids have been produced only under controlled conditions and were unknown to occur in natural wild populations.

The two hybrids are a considerable distance from one of the parents, L. formosana. The other parent, L. styraciflua, is abundant at this location. Since Liquidambar species are wind pollinated (anemophilous) trees, the great distance of the hybrids from the large Formosan Gums, would support the conclusion that the male parent was L. formosana and the female parent was native L. styraciflua.  Its more feasible for pollen grains to travel long distances than it would be for fruits and seeds.

I have repeatedly visited both hybrids all spring and summer, searching for any evidence of flowers.   As neither shows any evidence of having flowered and no fruit have been found, I suspect they may be sterile.

The two hybrid trees,  discovered by chance, were only noticed because of their bright yellow, fallen leaves. Now that I know the hybrid exists on Avery Island, I will continue to look for them, and I am optimistic that more will be discovered.

 

The Avery Fern – Pteris cretica var. albolineata

 

 

Pteris cretica  (Pteridaceae)  The Cretan Brake Fern, The Avery Fern

Pteris cretica, almost pantropical in distribution, is so common in cultivation and escapes so easily in warmer regions that its true native home remains uncertain, although it is thought to have originated on the island of Crete.  Some authorities have labeled it indigenous to tropical America, including several states in the Southeastern United States.

The earliest record for Pteris cretica in Louisiana is from Avery Island on October 18, 1910, by R. S. Cocks, a botany professor at Tulane University.  He visited the island three years later, in April 1913, and made a second collection of the fern, commenting on the label “Deep ravines, very abundant.”  1913 was long before the formation of Jungle Gardens and the beginning of the exotic plant collections, indicating that the fern was not introduced to Avery Island as part of horticultural expansion. This information supports John Small’s claim that Pteris cretica could be indigenous to Avery (and other parts of Louisiana) as well as Florida.

There are two varieties of Pteris cretica that occur in the wild in Florida and Louisiana. Both have been found on Avery Island and both have been referred to as the Avery fern.  Pteris cretica var cretica is represented by herbarium specimens from collections up until the 1960s (this is the only variety collected on Weeks Island), but Pteris cretica var. albolineata is the variety now found living on Avery.   P. cretica var cretica has all green foliage, whereas albolineata has a bright white stripe down the middle of each leaflet.  Prof.  Clair Brown of LSU visited Avery Island many times and wrote about these ferns in his 1942 publication; Ferns and Fern Allies of Louisiana.   He states:  “It has been known there for a long time as the Avery Fern. . .” He also mentions the albolineata variety as being  “cultivated in large quantities in Jungle Gardens.”  It would be expected that by this time, the albolineata variety was brought into cultivation there by McIlhenny. Unless there is another discovery of variety cretica, it appears that albolineata is the only variety that currently survives on Avery.

I began exploring the salt dome islands of Weeks and Avery in 1971.  Prof. W. D. Reese of USL took me to a location on Weeks Island where Pteris cretica had previously occurred in abundance.   We found but a single specimen on a ravine wall that once had a thriving colony of hundreds of plants.  The plant was in such poor condition, with only a single badly tattered frond, that I considered it unworthy of making a collection.  Little did I know that would be the only plant I would find for the next 45 years.   We noticed that the ravine sides were covered in tall, clumping grasses, which indicated that the forest canopy had been seriously disturbed, allowing excessive sunlight to reach the ravines, potentially drying them out and making it very unsuitable for the ferns to persist, much less thrive.

From the 1970s-present, I explored the myriad forested ravines on Avery Island at every opportunity.  During that time, I also made several return trips to Weeks Island, always in search of the Pteris fern.   Unfortunately, the data from the specimens of the early 1900s did not document locations accurately enough that one could revisit them.   Reese and Thieret in their Botanical Study of the Five Islands, completed in the mid 1960s, found Pteris cretica on Weeks, but not on Avery.  It seemed like the fern might have completely vanished from Avery Island.  I always held out hope, however, that I would rediscover it in the “next” ravine I explored.

On October 17, 2016, I was guiding a group of university botany students on an afternoon tour of Jungle Gardens.   As we ventured on the trail in the Palm Garden, much to my surprise, I caught sight of two young plants of the Avery fern growing among the roots of a large tree along the path.   I said nothing, maintaining my composure, but I was elated to finally rediscover this fern growing on Avery Island after all the many years I had searched for it.  The following day I returned to the spot to observe the two plants in detail.  Both were juvenile plants, indicating a recent dispersal, no doubt from older mature plants.  Immediately, I began searching the nearby ravines and gullies near this location.   To my disappointment, I was unable to locate any additional ferns.

One month later, on December 16, while exploring near Sunken Gardens with Dylan Derouen, we found a weedy, disturbed area with an abundance of fern species.  As we made our way up the hillside, we found two more plants of Pteris cretica.  These were very large plants growing about 10-12 feet apart.  One was at the base of the hill, the other, a much larger plant, was higher up on the slope.   Both had fully mature, fertile fronds.  I showed these plants to Bernard Patout.  A few days later, not far from that site but inside Sunken Gardens, Bernard found a single juvenile Pteris fern growing among the stone work of a retaining wall and called it to my attention.

A full year later, December 17, 2017, while exploring for seedlings of the newly discovered Gingko trees near Bird City, I discovered more Pteris ferns.  Several distinct clumps of mature plants were scattered along the banks of a shady, shallow ravine that lies behind the grove of Giant Timber Bamboo not far from the Gingko trees.

After so many decades of failed searches for the Avery Fern, it has been rediscovered, thriving on the island, though in smaller numbers than decades past. I am optimistic there are more Pteris cretica populations waiting to be found on Avery Island.

 

Daphniphyllum macropodum

 

Daphniphyllum macropodum  (Daphniphyllaceae)

The identity of the evergreen trees in a grove along a small portion of Holly Hedge Road in Jungle Gardens eluded inquisitive visitors for many years.  The grove consists of perhaps a dozen trees, several of which are quite tall, although their trunks are not particularly large.  Those who saw the trees thought the stiff, leathery evergreen foliage resembled members of  the Laurel family, or perhaps the Magnolia family or maybe even some relative of Rhododendron. No one, however, knew the true identity of these trees.

Most of these trees are hidden behind large hollies and generally not visible while driving the roadway.   A couple of trees occur on the banks of both sides of the road, but finding them is not easy because of the large hollies that abound.  Additionally, two trees are some distance from the grove. One very young tree, growing in a wooded area near the entrance to Holly Hedge Road, is likely the result of recent seed dispersal.  The other, found by Mike Richard, Sr., some years ago, is a tall, mature tree, located on the summit of a forested ravine near the Old Nursery and just below the Sunken Gardens. This single large tree could be the last survivor of a possible former planting or another seed-dispersed plant from the main grove.

In late winter and early spring, the foliage produces a very attractive flush of color.  The leaves, which are arranged in a tight whorl or spiral, give the tree a very colorful appearance. The petioles (the supporting stalk of a leaf) of each leaf at the tip of a branch are bright pinkish red.  This bright petiole color lasts for several weeks, but eventually, as the leaves mature and age, it fades to green.  It appears the color of new leaves may provide the primary ornamental value of the tree.

During the spring of 2017, my first full year in Jungle Gardens, I visited these trees regularly in anticipation of finding flowers. On March 3 when I visited the grove of trees they were flowering.  The flowers were most peculiar.  Emerging from the axils of the previous year’s growth, they resembled clusters of small berries radiating out from a central axis.  The flowers had no petals or sepals, consisting solely of reproductive structures.  All those I observed were all pollen producing male flowers.  I knew, however, that at least one female tree had to exist because of the abundance of seedlings volunteering below the adult trees.

Examining the trees on July 5, 2017, using binoculars, I located a single female tree with clusters of fruit high up in the canopy.  Dylan Derouen scaled the slender tree and collected a fruiting specimen.

Because of the unique nature of the flowers, the identification of the trees as Daphniphyllum macropodum was not difficult.  Daphniphyllym is a monotypic genus in the Family Daphniphyllaceae.  There are about 10 species in the genus consisting of small shrubs and trees found in China, Japan, and Korea.  Like all species in the genus, D. macropodum is dioecious, meaning male and female flowers are borne on separate plants.

Perhaps the most interesting discovery regarding these trees occurred after their identification.  One day in July 2017 I examined some of the many folders in Archives that may or may not contain information pertinent to Jungle Gardens.  Much to my delight, in the very first folder I selected and went through I found a letter and attached plant list from the Yokahama Nursery in Yokahama, Japan, dated November 24, 1919.  The letter, addressed to E. A. McIlhenny, discussed his purchase of seeds. There was a second page that served as an invoice or statement of purchase.   The very last entry on that second page was that of Daphniphyllum macropodum seeds he had purchased.

We now had a document in Archives with the plant’s name and the date of acquisition.   Ninety-nine years later, this species is still flourishing in Jungle Gardens.

 

Brush Holly – Xylosma conjestum

 

 

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.

 

Paupers Tea – Sageretia thea

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.