The Si-Hong

The Si-Hong just over a year ago began the 2024 season as this runty little thing I couldn’t help but love:

Baby Si-Hong jujube tree in 190 mm diameter pot
© Optimate Group Pty Ltd

and which went on to grow these fruiting branchlets:

Fruiting branchlets on Si-Hong jujube tree
© Optimate Group Pty Ltd

Which, being deciduous, all fell off over winter this year 2025, and so this little fella again looked as he began (I never took a photo, so yes, this is simply the same photo as the first one above, for effect!):

Baby Si-Hong jujube tree in 190 mm diameter pot
© Optimate Group Pty Ltd

In the 13th December post update, I wrote:

But come the following spring, with their tree now settled in, there is every chance an extension branch bud will shoot and cause that tree to double and sometimes even triple in height in just weeks.

Well, a year later it is that following spring, and would you look at this!

New extension branch on si-Hong jujube tree
© Optimate Group Pty Ltd

I didn’t even notice this until two days ago. It just shot out of nowhere, as they do! Runt no more — that new, permanent extension branch has now not quite tripled the height of this tree in a few short weeks.

Here’s a close up of the extension branch coming out of the mother branch:

Close-up of extension branch emerging from mother branch
© Optimate Group Pty Ltd

The very thin stems coming off that are this year’s fruiting branchlets, and you may even be able to see the flower buds forming on the upright one closest to the camera.

The Two Cuttings

Back in August 2024 I discovered two sole surviving cuttings from at least sixty failed others — jujube trees are notoriously difficult to strike from cuttings, like Japanese maples. These two were, quite frankly, miracles, as it wasn’t from years of trying countless other times. Here they are on 21st January 2025:

Miraculous jujube cutting number 1
© Optimate Group Pty Ltd

Miraculous jujube cutting number 2
© Optimate Group Pty Ltd

and four weeks later on 18th February 2025:

Miraculous jujube cutting number 1, four weeks later
© Optimate Group Pty Ltd

Miraculous jujube cutting number 2, four weeks later
© Optimate Group Pty Ltd

The stronger cutting was labelled a Silverhill, and went on to develop Silverhill fruit (can you see where leafcutter bees have been?):

Miraculous jujube cutting number 2, four weeks later
© Optimate Group Pty Ltd

which I think the Satin bower birds took. The weaker cutting never fruited and I have no idea which cultivar it is, as I actually fished that piece out of the compost after having a change of heart and giving it a chance would you believe! (All the others I fished out went on to fail of course.)

I didn’t dare touch them that first season, but they couldn’t stay where they were another year, and so I re-potted them when they entered dormancy last winter 2025. I was very pleasantly surprised by the root mass, and while they look dwarfed in these 9 L Air-Pot containers, the roots justified this size and I felt an Air-Pot gave them their best chance to develop further.

Jujube cuttings in 9 L Air-Pot containers
© Optimate Group Pty Ltd

The delicate roots were probably a bit put out by the handling — and despite every care some roots on each did come away — but each cutting did reshoot this spring 2025. Here they are on 28th October 2025:

Jujube cutting number one in a 9 L Air-Pot container
© Optimate Group Pty Ltd

Jujube cutting number two in a 9 L Air-Pot container
© Optimate Group Pty Ltd

The graph below was published in The Washington Post on 19th September 2024, in the article “Scientists have captured Earth’s climate over last 485 million years”.
You can also read it here if caught by the paywall.

A 485-million-year history of Earth’s surface temperature
Source: Washington Post. ‘Scientists have captured Earth’s climate over last 485 million years’, September 20, 2024.
https://www.washingtonpost.com/climate-environment/2024/09/19/earth-temperature-global-warming-planet/

Click on the graph for a full-sized version.

This graph was based on the one in the original paper “A 485-million-year history of Earth’s surface temperature” by E. J. Judd et al., published 20th September 20204 in Science, Vol 385, Issue 6715.

I do not know the source of this graph below unfortunately. I would love to be able to cite it if anyone happens to know its origin.

Temperature of Planet Earth
Source unknown

Again, click on it for a full-size version — you’ll need it!
Please note the change in scale of the x-axis, as the graph itself says to do.
Also take the time to absorb every word of text on it, and the significance thereof.

It’s worth ending this post by revisiting these two graphs from My Take on the Carbon Dioxide Narrative: Conclusion, just because they are that good too!

Air temperature vs human CO2 emissions, 16 AD to 2010
Source: https://joannenova.com.au/s3/jonova.s3.amazonaws.com/corruption/climate-corruption.pdf

Geological timescale: Concentration of CO2 and temperature fluctuations
Source: https://youtu.be/GH8v5aCbZBs?t=797

Local pal Sandra was first, seeing a tree here, at Bemm River in Victoria. Again the naming confusion that seems to follow this species complex, but it is what it is…

Please do check out the photos there — I have to assume copyright applies, otherwise I’d reproduce them here.

Thanks heaps Sandra!

Then pen-pal Helen from Melbourne shared the photos below, of a tree in Wattle Park, Melbourne, Victoria, after learning of its existence via this link in the Lone Pine article.

This very tree was grown from seed from the cone retrieved by Private Thomas Keith McDowell from the actual Lone Pine!
Making this indisputably Pinus brutia, the Turkish Pine and not Pinus halepensis, the Aleppo Pine. (The second plaque in the photos below say this too.)

Sadly this and one other tree at Warrnambool’s Botanic Gardens are the only two survivors of the four originals grown from that seed.

Lone Pine descendant, Wattle Park, Melbourne, Victoria, Australia
© Helen Flynn

She said, “I can’t help but think it has also self sown as its little friend bears a very strong resemblance.”

Lone Pine descendant, Wattle Park, Melbourne, Victoria, Australia
© Helen Flynn

Descendant of the Lone Pine descendant? Wattle Park, Melbourne, Victoria, Australia
© Helen Flynn

The commemorative plaques (click each to enlarge):

Commemorative plaques by the Lone Pine descendant, Wattle Park, Melbourne, Victoria, Australia
© Helen Flynn

Commemorative plaques by the Lone Pine descendant, Wattle Park, Melbourne, Victoria, Australia
© Helen Flynn

The white and red diamond at top left of the first plaque is the same as atop the plague at the Wollongong Botanic Garden:

Plaque commemorating the planting of a descendant of The Lone Pine of Gallipoli, located in the Wollongong Botanic Garden, Wollongong, NSW, Australia
© Optimate Group Pty Ltd

I’d welcome any Australian military historians’ input here, but from here and here: this diamond shape signifies the Second Division of the Australian Imperial Force; the white top half signifies the 4th battalion of any infantry brigade; and the red bottom half signifies all Victorian brigades.

This white on red diamond specifically signifies the 24th Australian Infantry Battalion of the Sixth Brigade of the Second Division of the AIF. (As the fourth battalion of the sixth brigade is the 24th overall.)
The shorthand for this is 2/24th Batt AIF.

Luckily for me, that blue T-shape on the right of the first plaque in Helen’s photo popped up while I was searching for the meaning of the diamond, for example here, as I would never have been able to work that one out otherwise! It is a WWII patch of the 2/23rd Batt AIF used from 1942-46.

It originally looked like this, but was changed to the one on the left here after the siege of Tobruk. The T-shape stands for Tobruk.

Thank you ladies both!

What a farce: "Vegetative Electron Microscopy"
Source: a still taken from a video by Sabine Hossenfelder entitled “AI Slop Is Spreading In Science, Too”
https://www.youtube.com/watch?v=hVkCfn6kSqE&t=203s

Science has been corrupt(ed) for ages. I can’t point to a specific decade or even century, but I know I’ve been jaded since the 90s, and I came to the jaded party pretty late. The more I look into it the further back I go, and I can point to examples from the 1800s.

Quite simply, pipers (researchers) play the tunes they’re paid to play (by research grants). But it goes deeper: in a world of “publish or perish” it is only natural that an entire industry of “pay to publish” had sprung up to meet this need. Yes, whether genuine ground-breaking research or complete and utter drivel, there is always someone who will gladly publish it for you — a few thousand US dollars later, and congratulations, you are now a published researcher in a journal (degree of quality varies), who can cite your own work for more grants! Rinse. Repeat.

(I stress that the intent is not always sinister, as that link will show. This approach arose from the digital age putting financial pressure on the traditional publishing model of printing sometimes inch-thick journals posted out monthly or quarterly to subscribed academics, libraries and research institutions worldwide. But it is very much open to abuse, and it is abused.)

And now, surprise surprise, ‘AI’ (very much artificial and very much not intelligent — see below) has been adopted by lazy, corrupt, incompetent, immoral, unethical (I’m running out of adjectives) shills to ruin science even further.

This short video is well-worth watching for a quick summary of all that is going on. It’s quite shocking and the ramifications are horrifying.

And if, through no fault of your own, you do not understand how ‘AI’ really works, and you do currently believe that AI really is intelligent, I sincerely hope that the 2:50 mark on “vegetative electron microscopy” (from where the header graphic comes from) changes your mind completely. And please keep reading below for more on this.

Sabine concludes with, “But the way it currently looks, the future of science isn’t about finding truth — just about generating statistically plausible sentences about it.”

A brilliant summation, but the true significance of her words is very underplayed here.

You see, ‘AI’ language models ARE literally nothing more than the stringing together of words and phrases that statistically are highly likely to occur together. Most people do not understand this. And our “vegetative electron microscopy” friend above couldn’t be more concrete a proof of this.

Please do take the time to read this somewhat lengthy but highly informative and very easy to read article: The LLMentalist Effect: how chat-based Large Language Models replicate the mechanisms of a psychic’s con. This will give you a much better grasp on just how insidious ‘AI’ truly is.

For more on how easily we can be manipulated, please watch this video — thanks Jason! — which is 100% AI-generated. Most (not all) of the generated imagery is indistinguishable from reality without deep analysis. (It can’t generate images of words though! You can’t help but notice the appalling captions when they appear, but also look closely at any background signage that appears! All gibberish.)

I shall conclude this article with this wise and insightful comment underneath that video:

@frantz4318
You know what? As crazy as it looks, I think the world needs this… Finally we cannot trust anything online. This is maybe the only way for people to connect in person, irl. I’ll continue to enjoy hiking, biking and fishing with kids and spend less and less time online

Fair warning: this post will be full of generalisation and speculation, for the simple reason that a) not much is actually known about this phylum (all that is known is deduced from genetic analysis of DNA extracted from the soil at that depth), and b) I don’t know the environment of that soil (pH, temperature, composition, permeability, that kind of thing).

One very noteworthy point is that there are bacteria that deep at all — "life” and “twenty metres down” are not two concepts most people consider as coexisting.

It is also important to know that many substances are carried by water down a soil profile into groundwater which can be very, very deep. (This site states that groundwater can be “thousands of feet below the surface”. Two thousand feet is almost 610 metres.) These substances can be anything — simple nutrients such as calcium and nitrate; manmade chemicals such as herbicides, other pesticides and fertilisers; or heavy metals and other industrial waste such as oils and microplastics.

How many of these reach groundwater depends on both substance amounts and the properties of the soil profile they travel through. For example, many substances will adhere to clay particles or organic matter en route down the profile. But this is complicated by soil temperature and/or pH along the way possibly altering some substances chemically, which may then affect the amount of adsorption positively or negatively.

Some substances — even pesticides and industrial waste — are broken down by microbes, but again soil pH and/or temperature may dictate to what extent this occurs.

Soil temperature and/or pH may degrade a substance outright into other substances, making them more, or less, adsorbable or biodegradable.

It’s pretty complicated stuff, and any substance passing through a soil profile not filtered out beforehand, so to speak, by physical, chemical, or biological means, is likely to end up in, and contaminate to some degree, groundwater.

Which brings us back to this new phylum.

What is interesting is that this phylum so deep down is known to be active — again, many people would not realise just how inactive microbes can be in situ. Many microbes actually exist most of the time in a dormant state, and often as hardy, super-tough long-lasting spores.

All those images and (sped-up) videos of rapidly growing bacteria “everyone” is familiar with are highly deceiving — those are of medically-important bacteria growing in ideal conditions of warmth, food and oxygen in a laboratory. If they really grew like that “in the wild” we’d be overwhelmed by the sheer numbers and bulk of them.

I couldn’t find any temperature data on the soil the CSP1-3 phylum inhabits, but this 2003 study measured temperature in a borehole in Nicosia, Cyprus, and found it to be a consistent 22.5 °C between 15 and 50 metres in late December (their winter). If soil temperatures globally also don’t fluctuate at these depths, then this temperature may be indicative of what the new phylum experiences too.

This also is worth noting, as this makes them psychrophiles: microbes able to metabolise, grow, and reproduce at low temperatures. (Some psychrophiles can do these at minus 20 °C!)

While +20 °C doesn’t sound particularly cold, bear in mind that we, for example, maintain an internal temperature of 37 °C. We’d die should our core temperature drop to 20 °C, as enzyme activity would either cease to function outright, or be so slow as to not sustain life, as our enzymes work optimally at (surprise!) 37 °C.

Enzymes are needed for metabolism, growth, and reproduction, and are very much temperature-dependent to function. This is why foodstuffs tend to keep longer in the fridge — the enzyme activity of most food-spoiling microbes has slowed if not stopped altogether at 4 °C.

One notable exception is when refrigerated meat spoils — the bacteria in this case are also psychrophiles with enzymes enabling them to grow, metabolise and reproduce at 4 °C. This reproduction and growth manifests as a distinctive visible slime, and the by-products of their metabolism manifest as a distinctive odour.

So, metabolically active bacteria at cool temperatures does signal the possibility of their ability to metabolise and thus minimise substances entering groundwater.

Also worth noting is that there is every chance that there is little to no oxygen at this depth, making these bacteria either anaerobes (unable to survive in the presence of oxygen) or facultative anaerobes (tolerating the presence of oxygen but not using it).

This in itself isn’t amazing, as our gut microbes are also anaerobes or facultative anaerobes. (Anaerobes can also be found in the mouth of all places, protected by plaque from all that oxygen!) But what does make this interesting is that anaerobic environments make for some pretty interesting metabolic pathways — fermentation is but one such example.

Fermentation has economic significance to us for without it there’d be no cheese, wine or beer, but many other anaerobic pathways have far more important environmental significance. Exploring the chemistry here is just too involved and complex for one post, but please take as read that anaerobic pathways are very important in the recycling of carbon, nitrogen, iron and sulfur through the biosphere, lithosphere, hydrosphere and atmosphere.

Some anaerobic pathways also make some heavy metals less bioavailable, and have huge potential in the bioremediation of contaminated industrial sites. Some anaerobic bacteria can even metabolise ionic mercury and cadmium (both highly toxic) and radioactive uranium and vanadium to less dangerous forms.

So, anaerobic bacteria at depths where potential pollutants may exist also signals the possibility of their ability to minimise substances entering groundwater.

Thus to summarise the significance of deep-soil bacteria, whether this phylum or any other, is this:

• they are found where potential groundwater contaminants can be found;
• they are known to be active, meaning that they are metabolising, growing and reproducing at those depths;
• they are likely to be psychrophiles, with enzymes functional at temperatures lower than would normally denature potential contaminants chemically
• they are likely to be anaerobes, or facultative anaerobes, and thus likely to have biochemical pathways able to metabolise potential contaminants aerobic organisms cannot

And. going out on a complete limb here, there is a good chance that the reason this phylum is metabolically active at all is because these ever-present potential contaminants are proving to be a rich food source for them. Who knows, maybe a century ago they too were mostly dormant like any other soil microbe, and it’s only the modern industrial age which has changed their environmental response?

Now this would be wonderful beyond belief if so, for it would show that nature is far more resilient than we give credit for, and able to rise to any challenge through the power of microbes!

The Bosphorus (red), the Dardanelles (yellow), and the Sea of Marmara in between, are known collectively as the Turkish Straits
Attribution: User:Interiot, CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5), via Wikimedia Commons

The Gallipoli Peninsula
Attribution: Simeon Scott. (User:Simeon~commonswiki), modified from https://en.wikipedia.org/wiki/File:Gallipolimap.jpg (Attribution: Jheijmans at the English Wikipedia, CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/), via Wikimedia Commons)

Australia was but 14 years old, having federated on 1st January 1901. New Zealand had chosen not to join this federation, but became a Dominion in 1907. (New Zealand never had an official independence day, but full sovereignty evolved slowly over decades, with full sovereignty dating to 1947, and complete and unlimited sovereign power dating to 1987.)

Anzac Day is observed by Australia, Christmas Island, Cocos (Keeling) Islands, Cook Islands, New Zealand, Niue, Norfolk Island, Tokelau and Tonga.

My great-grandfather, Edgar Francis Douglas, of the 3rd Light Horse Regiment, Australian Imperial Force, was wounded at Gallipoli on 15th June 1915. His regiment first fought in Egypt from December 1914 to May 1915, and arrived at Gallipoli on 12th May 1915.

That following August 1915 was the Battle of Lone Pine, between the ANZAC and Ottoman Empire forces. The name came from a single Turkish or Calabrian Pine (Pinus brutia) left standing, prior to the battle, of a stand which had been cut down by the Turks to construct trenches. That lone tree eventually succumbed to shelling.

The Lone Pine, Gallipoli
Attribution: Australian War Memorial, CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0), via Wikimedia Commons

A cone from The Lone Pine was collected by an Australian soldier, Private Thomas Keith McDowell, and brought back to Australia, where his aunt Emma Gray successfully grew four seedlings. These seedlings were later planted in four locations in Victoria in the early 1930s. The rest of the story, with photos, can be read here.

Another soldier, Lance Corporal Benjamin Smith, sent home cones from the branches covering the Turkish trenches, from which his mother grew two seedlings. These trees are from the Aleppo Pine (Pinus halepensis), and that story can be read here.

The Turkish (Pinus brutia) and Aleppo pine are closely related, and Pinus brutia was once and still is considered a subspecies of Pinus halepensis by some botanists. The two form a species complex, a group of species so closely related that it can be extremely difficult to distinguish them based on visible features, and deeper microscopy work or genetic analysis is sometimes required.

This confusion may explain the Australian War Memorial selling seedling descendants of Benjamin Smith’s cones it calls both Aleppo pines and Lone Pine seedlings. But naming confusion aside, it is still a shame that they don’t sell descendants of the Lone Pine cone itself as well, whether called Aleppo or Turkish.

There is a descendant of one of them at the Wollongong Botanic Garden! The plaque says this:

Plaque commemorating the planting of a descendant of The Lone Pine of Gallipoli, located in the Wollongong Botanic Garden, Wollongong, NSW, Australia
© Optimate Group Pty Ltd

Here are several photos of it from different perspectives:

A descendant of The Lone Pine of Gallipoli, located in the Wollongong Botanic Garden, Wollongong, NSW, Australia
© Optimate Group Pty Ltd

A descendant of The Lone Pine of Gallipoli, located in the Wollongong Botanic Garden, Wollongong, NSW, Australia
© Optimate Group Pty Ltd

A descendant of The Lone Pine of Gallipoli, located in the Wollongong Botanic Garden, Wollongong, NSW, Australia
© Optimate Group Pty Ltd

Canopy of the Lone Pine descendant, located in the Wollongong Botanic Garden, Wollongong, NSW, Australia
© Optimate Group Pty Ltd

Needles of the Lone Pine descendant, located in the Wollongong Botanic Garden, Wollongong, NSW, Australia
© Optimate Group Pty Ltd

Needles of the Lone Pine descendant, located in the Wollongong Botanic Garden, Wollongong, NSW, Australia
© Optimate Group Pty Ltd

Trunk base of the Lone Pine descendant, by commemorative plaque, located in the Wollongong Botanic Garden, Wollongong, NSW, Australia
© Optimate Group Pty Ltd

Lest We Forget.

Michigan State University put out this press release on 7th April 2025, on the discovery by Professor James Tiedje, in both its Department of Microbiology, Genetics and Immunology, and Department of Plant, Soil and Microbial Sciences, of an entire phylum of bacteria 20 m underground. This phylum, CSP1-3, appears descended from aquatic bacteria which frequented hot springs and fresh waters millions of years ago.

This image below is on the press release page, but is completely unreadable! I’ve enlarged it below:

A diagram showing the evolutionary history from an aquatic organism and adaptive traits of CSP1-3 phylum for each habitat
Source:
https://msutoday.msu.edu/news/2025/msu-scientists-discover-new-microbes-in-earths-deep-soil
MSU scientists discover new microbes in Earth’s deep soil

This phylum may play a vital role in the purification of water, and may harbour genes which may combat persistent environmental pollutants.

But First, What is a Phylum?

A phylum is the third-highest level, or rank, in taxonomy. (Botany uses ‘division’ for ‘phylum’.) Phylum (or division) comes after domain and kingdom, and is followed by class, order, family, genus and species:

The major taxonomical ranks
Attribution: Peter Halasz. (User:Pengo), Public domain, via Wikimedia Commons

These are the major ranks. Minor ones such as subphylum, suborder and subgenus also exist, as do even more minor ones such as tribe and subspecies.

This ‘ranked taxonomy’ is the traditional and original hierarchy used in the classification of organisms, and dates back to the father of taxonomy, Carl Linnaeus (1707-1778).

A more modern system known as ‘cladistics’ runs in parallel and organisms are classified based on phylogenetics, or how closely related they are based on their genetics. (This is why many plants are forever being renamed and moved from one family to another, as genetic analysis shows them to be more closely related to other groups than their outward appearance would show. Did you know the entire Agave and Yucca genera were moved into the asparagus family Asparagaceae based on this?!)

A New Phylum is Quite a Big Deal!

By way of example, we, humans, are classified as follows:
Domain: Eukaryota (also written Eukarya — organisms with a membrane-bound cell nucleus)
Kingdom: Animalia
Phylum: Chordata (having a dorsal nerve cord)
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Homo
Species: sapiens

The new bacterial phylum is classified:
Domain: Bacteria
Kingdom: (Not stated. There are four under Bacteria: Bacillati, Fusobacteriati, Pseudomonadati and Thermotogati)
Phylum: CSP1-3 (the name Sysuimicrobiota has been proposed)

A phylum is quite high up in taxonomy, and thus includes a lot of organisms. The higher up one goes, the more organisms are included by definition.

For example, there are only three domains*: Bacteria, Archaea, and Eukaryota. Every single known organism fits perfectly into one of these three groups. There are no outliers and no grey areas. The distinctions between the three are so precise that any newly discovered species could be classified into a domain in no time at all.

Phylogenetic Tree of Life
Attribution: Maulucioni, CC BY-SA 3.0 , via Wikimedia Commons

* Under the three-domain system. There is also a two-domain system: Bacteria and Archaea, with Eukaryota included in Archaea. This was ever so subtly referenced in  The xkcd Stromatolites Comic. There are arguments for either system, but the point still remains that all three labels — Bacteria, Archaea and Eukaryota — are still recognised. There is no fourth label at this highest level.

So second-nature is this, that any newly discovered organism not fitting into one of these three — or two — domains would send shockwaves through the entire life sciences world and turn all understanding of the evolution of life on its head! It really would be that monumental a discovery.

Thus whilst not quite at that level, the discovery of a new bacterial phylum is still a very noteworthy event. These bacteria are like no others this high up in the hierarchy.

The phylum we are in, Chordata, dates right back to the Cambrian explosion, or the period when multicellular organisms burst onto the scene almost 540 million years ago, after billions of years of only single-celled life. Chordata includes all vertebrates and two invertebrate groups, and today has some 81,000 living species. Many, many more have gone extinct since the Cambrian began (all those famous dinosaurs are just some of these).

Bacteria are amongst the earliest forms of life, going back at least 3.5 billion years. About 43,000 species are known, but there would be many unknown ones again simply because it is just so difficult to find them, much less know they are there to be found at all.

To find a previously unknown bacterium is exciting, but to discover an entire phylum is another level of exciting again!

And the significance of this phylum shall be covered in the next post!

Plants are so incredibly diverse in their morphology, that it wouldn’t surprise me if there were more descriptors in botany than in zoology, biochemistry and microbiology combined! (And that is truly saying something.)

Every minute detail of a plant has at least one word for it. By way of example, let’s describe a jujube leaf botanically — pull up this reference, and this page too for more terms, and follow along!

Chart illustrating leaf morphology terms
By derivative work: McSush (talk)Leaf_morphology_no_title.png: User: Debivort - Leaf_morphology_no_title.png, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=7681206

Shape and Arrangement

A leaf in botany is also known as a blade or a lamina. (two words right there!)

Below is a jujube fruiting branchlet, upperside (and can you see what looks like leafcutter bee activity?):

Jujube fruiting branchlet, upperside
© Optimate Group Pty Ltd

and underside:

Jujube fruiting branchlet, underside
© Optimate Group Pty Ltd

At first glance it may be mistaken for a compound leaf, one in which the blade is divided into leaflets. (Jacaranda mimosifolia and ferns are examples with compound leaves.)
And (with reference to the morphology chart) a pinnate one specifically. (And an alternipinnate one at that.) 

But when budding/flowering, this is more clearly a branch (branchlet more accurately), as no leaf has buds or flowers along it like this:

Shanxi-Li fruiting branchlet
© Optimate Group Pty Ltd

Distal leaves on Shanxi-Li fruiting branchlet
© Optimate Group Pty Ltd

So a jujube leaf is a simple leaf. Let’s zoom in:

Jujube leaf, upper surface (left) and underside (right)
© Optimate Group Pty Ltd

The uppermost surface is on the left and the underside is on the right.

Again with reference to the chart, these leaves are arranged alternately along the fruiting branchlet — each leaf along a branch alternates in position from one side to the next, as opposed to an opposite arrangement, whereby leaves are arranged in pairs along a branch.

From this point on, descriptors can be open to interpretation, and one person’s description may clash with another. Adding qualifiers such as dimensions can help in some cases.

Also worth knowing is that there can be a lot of variation in leaf shape even on the same plant. For added complication (welcome to botany!), some species have juvenile foliage completely distinct from adult leaves. Brachychiton rupestris, the Queensland bottle tree, is a really good example of this — its juvenile leaves look like this, and its adult leaves look like this.

Thus the following is just my take, and you may or may not agree. But for what it’s worth:

A jujube leaf is very wide at the base (the bottom) and tapers to a blunt apex (the tip). To me the overall shape is ovate, but not quite. Partly because the tip tapers more to a point than ovate, and partly because the base is slightly cordate.

Therefore we could describe this leaf as being about 20 mm wide at the base, about 80 mm long, and 45 mm at its widest part a third of the length from the base’s edge.
It has an acute tip and a slightly cordate base.

Leaf Margin

‘Margin’ is another word for ‘edge’. And again this leaf doesn’t fit a neat little pigeonhole. The edges are toothed and not strongly pronounced, and somewhat serrate-crenate.

Venation

You may have to click on the leaf image immediately above to view at full size, but the venation is very clearly reticulate.

Hairs

We can go still further! Jujube leaves are glabrous (hairless) on both sides.