This section began innocently enough as a simple info blog about jujubes. But during the dormant winter periods with no live action to write about, I went back to my roots (ha!) to write more on soil, biochemistry, and soil microbiology in general. I found myself wanting to keep going, and this blog was becoming less and less jujube-specific.
Thus it made sense to restructure everything.
This blog is now The Biosphere Blog, where I will continue writing about these subjects very dear to me.
(And here is my passion project From Soil to Fruit, a combination of the two and very much a work in progress. This is where topics in this blog are arranged in a more structured book-chapter format, to be explored in far more detail.)
Jujube tree trunks and branches are, botanically-speaking, stems.
A stem is one of several plant organs, and, like all organs plant or animal, is specialised for specific roles.
A stem is the plant organ which provides structure and support, as well as enables the transport of water and nutrients within the above-ground parts of a plant via the vascular tissue it contains.
A Plant’s Vascular System
Just as we have a vascular (circulatory) system, so too do the vast majority of plants. And just as ours transports water, nutrients and wastes, so too does a vascular plant’s.
Our vascular tissue comprises blood and lymph vessels and reaches all parts of the body. A plant’s vascular system is made of tissues called xylem and phloem, is in all stems and roots, and likewise reaches all parts of its body. Xylem carries water and some nutrients, and phloem carries the food produced by photosynthesis (called photosynthates).
Xylem walls further contain lignin, an incredibly complex carbohydrate polymer which confers rigidity:
This lignified xylem is what makes structural support possible in a plant.
A non-vascular plant is, not surprisingly, one without a vascular system, and thus does not have xylem and phloem tissue. Plants without xylem also lack lignin, and structural support. On land, such plants are small, poorly-differentiated, flat organisms like liverworts. Algae (most of which are not plants) are also non-vascular, poorly-differentiated, flat organisms — for them, their aquatic environment provides the structural support for larger growth.
Vascular plants on the other hand have two clearly differentiated structures: the stem and the root. (Though where a stem begins and a root ends isn’t always so clear.) The above-ground structure of vascular plants is determined by how their stems grow. Stems also provide support for other plant organs: specifically the leaves, cones (of gymnosperms), flowers and fruit.
As we’ve seen, stems are the plant organs which make the transport of water and nutrients above-ground possible. They are also, via lignified xylem, the organ responsible for structure and support. These functions alone classify stems as specialised organs, but there are several types of stem which go further still in their specialisation.
Some stems are underground. Tubers and rhizomes, for example, are specialised stems for storage. Other underground stems are specialised for reproduction, examples beings bulbs, and rhizomes again.
Jujube trees don’t have underground stems and none of these apply to them. The specialised stem types which jujube trees do have —and which are shared by many other species —are woody stems, branched stems, and thorns.
Woody stems are stems which are hardened by the growth of secondary xylem. These specialised stems provide additional strength and protection, and enable some species to grow to great heights and widths. Jujube trees can reach 10 m high by 6 m wide for example.
Branched stems are stems which are connected to, but not part of the central trunk. They may or may not be woody. A fancy botanical word for ‘branch’ is ramus, but a simpler word again is simply ‘branch’. (’Ramus’ is Latin for ‘a branch, bough, twig’ and its use is more common in anatomy than botany!)
(An example of an unbranched tree is a palm tree.)
Thorns are modified stems with sharp ends. These also provide protection and arise from buds.
Buds in turn are embryonic shoots — young stems with leaves.
Other specialised stems found on jujube trees are the pedicels and peduncles which support flowers and fruit.
A stem can be divided into nodes and internodes.
Nodes are the points of attachment along a stem, and where the leaves, thorns if any, and buds are located. The internode is the length of stem between nodes, and it is growth in this region which extends trunks and branches.
Last week we covered the location of jujube tree nodes and the two types of buds present at each node. (That post has since been updated to include a crash-course description of the branch types as well.) The post ended with a summary of what each bud type could develop into, and the promise of an attempt to predict what each active bud on the 2020 Ta-Jan blogging tree was likely to develop into.
Let’s delve in!
Here is the same photo from last week, with six nodes and the terminal buds labelled:
(There is another node below node 1 — node 0 we can call it — where the trunk meets the white tape, but I’m ignoring it here, as it won’t feature in this ongoing discussion of tree development.)
But before looking at each node, let’s first step back and examine the trunk as a whole, as this will help with our bud investigation. If you’re new to all of this, please just take my word for it for now — but when you know what you’re looking at, it’s clear that this trunk is a permanent branch extending from a fruiting mother branch. Only two types of branch arise from a fruiting mother branch: fruiting branchlets (predominately), and permanent branches (occasionally). Fruiting branchlets are thin and deciduous; permanent branches are thick and, well, permanent! And this one is very much permanent.
(The fruiting mother branch in the photo is mostly obscured by the white tape. It is not intuitively or obviously a ‘branch’, as it looks nothing like one! We’ll cover this branch type in more detail in a future post, or you can read up on it and the other types now here and here.)
A very strong main bud in that fruiting mother branch had broken dormancy last season to produce that permanent branch, which has now become the main trunk of this new little tree.
The photo above of the trunk was taken on the 24th September, 2020. The photos below are of close-ups at each of those nodes, twelve days later on the 6th October (yesterday).
The solitary secondary bud possibly grew a fruiting branchlet in its first (and only) year while the adjacent main bud developed a fruiting mother branch during that time. The fuzzy cluster above is of emerging fruiting branchlets from secondary buds within that mother branch. The main bud in this case is a weak main lateral bud and the secondary bud was possibly a weak secondary bud.
The main bud is dormant while the secondary bud looks to be developing a fruiting branchlet or possibly a secondary branch (I think a fruiting branchlet is more likely, but we’ll see soon enough!). The main bud in this case is a strong main lateral bud and the secondary bud is likely to be a weak secondary bud.
This one is a young fruiting mother branch with one fruiting branchlet already emerging, and visible is a secondary bud within the mother branch forming another branchlet. Alongside is the remains of a removed secondary branch, which had developed from a secondary bud. The main bud in this case is a weak main lateral bud and the old secondary bud would have been a strong secondary bud.
Node 4 is similar to node 3, with a removed secondary branch and a young fruiting mother branch growing fruiting branchlets.
Node 5 is similar to nodes 3 and 4, with a removed secondary branch and young fruiting mother branch growing fruiting branchlets.
Node 6 shows a dormant main bud and an active secondary bud that looks like a fruiting branchlet is on the way. (Again I feel this more likely than a secondary branch, but time will tell!)
This section here is showing all the signs of preparing to send out an extension branch with attached fruiting branchlets. Making this a strong main bud with many secondary buds. I’ll write more about this when it happens, and will leave this as the subject of a future post!
A ‘bud’, in botany, is a compact, undeveloped shoot which may develop into a twig/branch, leaf, or flower. The region in which buds are located is called a node, and the area between nodes is called an internode. Nodes are the points of attachment for branches, leaves and flowers. (Buds not arising from nodes, ie arising from unusual places, are called adventitious buds.)
The nodes in some species are very distinct — bamboo nodes, for example, are the thickened rings between the stem segments. The nodes in other species can be harder to find if leaves or branches aren’t present.
Jujube nodes on dormant trees are visible as single, slightly raised bumps which alternate (change sides) along a trunk and branches. This alternating pattern is behind the distinctive zigzag growth of secondary branches, where the direction of growth changes at each node. This can be seen in the photo below of a Redlands secondary branch:
Nodes on leafy jujube trees are of course very easy to spot with all the green growth sprouting from them! But even these trees may still have less visible nodes barely noticeable as bumps, especially on older wood. On really old wood the nodes tend to blend into the thickening branches until they are hardly visible at all:
Jujube trees are unique, in that each node contains two distinct bud types: a main bud, and a secondary bud. Let’s look further!
Jujube Tree Buds
The main and secondary buds are easier to see when dormant, but the Ta-Jan blogging tree was too fast for me by the time I thought of this post! Every single one of its nodes had an active bud, so I had to make do with older tree substitutes. These have more established branches and are more likely to have at least some nodes with slower-to-wake buds. Below is a Shanxi-Li node on a secondary branch from last year’s growth:
But not only do these trees have two types of bud, each bud may be of strong or weak vigour, and whichever one they are determines what they develop into.
Main Buds on Permanent Branches
Permanent branches are the ones that extend each year and which make up the shape of the tree.
Strong main buds on the ends of permanent branches (ie strong terminal main buds) produce the extension growth that make up the shape of the tree. Weak main buds on the ends of permanent branches (ie weak terminal main buds) produce fruiting mother branches (which look more and more like pine cones the older they become). Strong main buds along permanent branches (ie lateral main buds) are dormant, but the top-most one will break dormancy to produce a new permanent branch when the terminal strong main bud loses vigour. Weak main buds along permanent branches (ie lateral main buds) produce fruiting mother branches.
Main Buds on Secondary Branches
Secondary banches develop from permanent branches and have a distinctive zigzag shape.
Main buds along secondary branches are dormant in the first year but produce fruiting mother branches from their second year on.
Main Buds on Fruiting Mother Branches
Fruiting mother branches are comprised of highly compressed bundles of shoots. These shoots do not have leaves, but contain many main and secondary buds. As a fruiting branch grows a little each year, this cluster of shoots also grows in size, and with each passing year resembles more and more a pine cone.
Fruiting mother branches are not to be confused with fruiting branchlets, the only branch type which produces fruit.
Very strong main buds on fruiting mother branches can break dormancy to produce a new permanent branch. Strong main buds extend the fruiting mother branch by a millimetre or so each year.
Secondary Buds on Permanent Branches
Strong secondary buds on permanent branches produce secondary branches (the ones with the distinct zigzag shape). Weak secondary buds on permanent branches produce fruiting branchlets (not to be confused with fruiting mother branches — the branchlets are the ones on which fruit grows).
Secondary Buds on Secondary Branches
All secondary buds on secondary branches produce fruiting branchlets (not to be confused with fruiting mother branches) the first year. The main buds then take over this role from the second year on.
Secondary Buds on Fruiting Mother Branches
All secondary buds on fruiting mother branches produce fruiting branchlets.
The photo below shows the four branch types and indicates the location of the bud type each developed from. This is an incredibly complicated structure to grasp the first time, so by all means ask any questions in the comments if you need anything clarified.
Back on the 24th September 2020 I finally potted up the Ta-Jan blogging tree for 2020 which had been soil-less since July — it was still going strong but it had been long enough! — and that alone will be the subject of a future post.
But next week we’ll go back to the first photo of this post and zoom in on each of the nodes on that tree trunk to see which buds are growing, and attempt to predict which branch types will develop!
This earlier post described the four branch types peculiar to jujube trees: primary (extension) branches, secondary (non-extension) branches, fruiting mother branches, and fruiting branchlets. Also mentioned were the two bud types, main and secondary, and that each could have either strong or weak vigour. The type and strength of a particular bud determined the branch type that developed.
The focus in that post was on terminal main buds (those at the end of a branch), and how the strong ones produce permanent extension branches that form the structure of the tree, while the weak terminal buds produce fruiting mother branches.
This week picks up where we left off, with the primary branches, but this time we’ll cover the non-terminal buds. That is, the buds along a branch rather than at its end, and what these develop into. And from there we’ll go on to discuss how the other branches form.
Normally the main buds along a permanent branch remain dormant while that branch’s terminal main bud remains strong and produces extension growth. When that terminal bud weakens however, and produces a fruiting mother branch, some of the main buds further down the branch will break dormancy and produce new growth.
A strong main bud along a permanent branch will produce a new permanent branch that adds to the overall shape of the tree:
A weak main bud along a permanent branch may also break dormancy and produce a fruiting mother branch:
Remember how a fruiting mother branch — which looks more like a pine cone than a branch! — is a bunch of very compressed shoots containing several main and secondary buds? If a main bud in a fruiting mother branch then comes out of dormancy, a new permanent (structural) branch will again form:
A strong secondary bud along a permanent branch will produce a secondary branch. This branch type has a distinctive zigzag growth, caused by the alternating nodes changing the direction of growth:
Secondary branches do all their growing in their first year, as the terminal bud responsible for growth dies by the end of the first year. While a secondary branch will survive for many years, its end will deteriorate back to a node over time, where it dies:
During the first year’s growth of a secondary branch, its secondary buds at each node will produce fruiting branchlets, while its main buds remain dormant. These main buds then break dormancy in the second year to produce fruiting mother branches.
Here is a current season’s secondary branch showing fruiting branchlets from secondary buds. We know this branch to be less than a year old by its colour and texture — predominantly reddening but with hints of green still present, and with the shiny, smooth look of ‘green’ wood.
Below are fruiting branchlets from newly forming fruiting mother branches on a secondary branch in its second year of life. Again the colour and texture age the wood as between one and two years old, in that it is slowly developing a more brown-grey colour and has a more textured surface. Unlike the photo above, where the fruiting branchlets come from buds almost flush with the secondary branch, these branchlets come from slight extensions which are the growing fruiting mother branches. These mother branches will extend a little further and look more like pine cones with each passing year.
And here are fruiting branchlets from fruiting mother branches on an older secondary branch, which is noticeably more grey than the younger branches above. Mother branches only grow a millimetre or so each year.
As mentioned earlier, fruiting mother branches will develop from weak main buds on permanent branches. However, most branches of this type will come from the main buds on secondary branches. As the fruiting mother branches are the ones to produce fruiting branchlets, this means most fruit will come ultimately from secondary branches — branches which do not grow after the first season. Something to bear in mind when pruning, a topic we’ll cover in due course!
Also mentioned earlier was that a fruiting mother branch is a group of very compressed shoots comprised of main and secondary buds. The terminal bud extends the growth of the branch slightly each year, for about ten years after which it is no longer productive.
Fruiting mother branches can produce up to ten fruiting branchlets in a whorl:
The fruiting branchlets themselves come from weak secondary buds in the mother branch. (As well as from weak secondary buds on secondary branches as mentioned earlier.) Please read this if interested in further detail on the anatomy of a fruiting branchlet.
A peculiarity of jujube trees is that the fruiting branchlets are deciduous and have mostly fallen off the mother branches by the following winter. Some occasionally remain on the tree but they will never regrow:
and come away easily if knocked.
And that concludes the discussion on jujube tree branch development!
Going further, this post breaks down the structure of a fruiting branchlet in more detail, while this post describes the anatomy of a flower in more detail. And this post documents a flower’s life from bud to fully open and ready for passing pollinators.
All we need (I think!) to conclude the whole branch-flower-fruit thing is the documentation of a flower developing a fruit — and that is definitely coming!
Around 7pm the other evening I was perusing my trees, and — as I often do, gently pulled down a fruiting branchlet above to look more closely with my loupe at the flowers and developing fruits along it. To my absolute horror it came away in my hand! I reconciled myself by thinking that maybe it was structurally weak and always destined to fall off, and decided to make good of the situation by writing about it!
So here it is, the anatomy of a Shanxi-Li fruiting branchlet!
This was a large branchlet, about 385 mm along a straight line, but closer to 405 mm long, as measured by following every bend of the stem with a piece of string and then measuring the string. It was so noticeably large (most in my experience tend to be under 300 mm long) that I really do wonder if it was structurally weak and would have snapped off eventually as the developing fruit on it grew larger and heavier?
As with all new jujube branch growth during a season, the oldest part of this branchlet (which was closest to the fruiting mother branch) was turning red while the youngest part of the shoot was still the bright green of new growth.
The proximal end (of anything) is that closest to the point of origin or attachment. Here, the point of attachment of this fruiting branchlet was the fruiting mother branch. Conversely, the distal end (of anything) is that furthest away from the point of origin or attachment:
Here is where the point of attachment was:
And here is the proximal end of the branchlet, with a transverse (crosswise, cross-sectional) view of the point of detachment:
A node is the point along a branch from which leaves and other branches grow. An internode is the interval between two nodes.
The closest node (and leaf) to the fruiting mother branch was 15 mm away. The largest internode, and the third along from the fruiting mother branch, was 40 mm long. The internodes were then spaced at 30 mm intervals, then 25 mm intervals, and finally the last internode was just 3 mm long, but with still developing leaves, and would have lengthened by season’s end. The penultimate internode was 10 mm long.
The leaves are alternate, meaning there is a single leaf at each node. The leaves alternate sides along the branch, because the nodes alternate sides, hence the name. (The two other leaf arrangements defined in botany are opposite and whorled.)The largest leaf on this branchlet was 90 mm long and 55 mm across the widest part. The smallest leaf was 35 mm long and 15 mm across its widest part. The very small, still developing leaves at the distal end were just 5 mm long.
The flower arrangement (inflorescence) at each node is a simple cyme. A cyme is a group of flowers in which the oldest flower occupies the end of the peduncle (the main supporting stalk, or main axis), and newer shoots come from the sides of that stalk.
As the flowers differ in age within a cyme, so too do the fruits which develop from those flowers:
And as flowers (and fruits) differ in age within a cyme, so too do they differ in age along a branchlet. Those at the fruiting mother branch (proximal) end are oldest and those at the (distal) tip are youngest. Here, these cymes which were closest to the fruiting mother branch have no flowers anymore, but do have the largest fruits. Note too the change in colour of the branchlet when moving from the proximal end towards the distal end:
The cymes at the very tip of the branchlet have the youngest flowers of all — minute buds which have only just begun development:
The cymes between these extremes occupy a gradient of mostly fruit and some flowers, to some fruit and mostly flowers, to mostly flowers and some buds, to mostly buds and some flowers. Note too the colour change along the branchlet. You can tell that the banchlet segment in the top photo below is closer to the fruiting mother branch than the segment in the lower photo below, as it is more red at the proximal end:
Fruiting branchlets are the only branches on a jujube tree to produce flowers and fruits — so writing about one allowed me to slip more botany in than I otherwise could have with another branch type!
To go further and discuss the flowers and fruits on a fruiting branchlet really require their own posts to do those topics justice. I covered Photo Journal: Anatomy of a Jujube Flower earlier, and fully intend to do one on fruit later, but here is a good place to wrap up this post with, I guess, a teaser for what will come!
The following photos are of the largest fruit on the branchlet discussed here. This fruit was the most proximal and 8 mm long.
Do revisit the flower anatomy post — this page may help too — and see if you can work out what the two little brown dots on this fruit’s distal end are. (Distal in this context refers to the end of the fruit furthest away from its point of attachment, and not to be confused with the distal end of the branchlet discussed above.)
What about now?
Yes, those are the two stigmata and the branched style of the original flower! The green fruit you see is the maturing ovary of that flower. But more on that to come later!
The proximal end of the same fruit reveals the sepal remnants:
Let’s (almost) bisect it. I say ‘almost’, as a real bisection would have had two equal halves, each with that delicate little peduncle cleaved cleanly in two along its length. Sorry but that was never going to happen!
Just looking at this you may well be able to make out which parts will become the seeds, the stone that contains the seeds, and the fruit itself? This, and what happens as the fruit grows, is definitely the topic of a future post!
This week I thought I’d follow up on the last paragraph of this older post that had been getting some recent attention, as well as my comment under that post.
Fig. 1 below is the very same Lang referred to. This photo was taken on 19th October 2018, about two months after being potted into a 30 cm pot in August 2018:
Fig. 2 is the very same Li also mentioned, again two months after potting in August 2018, and photographed on 19th October 2018:
Both trees are of similar age, and you can see why I described the Li as ‘runty’ in that comment! It looks rather lost in that pot…
Fig. 3 below was taken a bit over a year later, on 7th November 2019. These are the same two trees in Figs. 1 and 2, side-by-side. The Lang (Fig. 3, left) and Li (Fig. 3, right) are in the same 30 cm pots of August 2018, and had been watered and fertilised similarly the whole time. They had otherwise not been disturbed (though I will pot them up next winter 2020).
The Lang at time of photo was about 110 cm high from base of trunk to tip of leader (longer if accounting for the angled growth), as marked. The Li was about 75 cm as marked (and longer again if accounting for the very angular growth!).
And Fig. 4 is the same photo, but showing how each tree had grown (or hadn’t!) by mid-spring 2018 and mid-spring this year 2019:
The Li is growing exactly as the Ta-Jan and Adrian’s Chico did. That is, it wasn’t, and then it was, with gusto!
But why was the growth of the Li (and Chico) so different to that of the Lang? To find out, we will need to zoom in closer on various branches and examine them —and if you’re not familiar with how these trees grow you are about to learn quite a bit!
But first a brush-up on some terminology to make this easier. Common to plant stems, irrespective of species, are nodes, the points from which leaves and branches grow. Some nodes are really distinct, such as the thickened rings between the segments of bamboo stem. (The botanical term for a segment of stem between nodes, regardless of species, is internode.) As leaves and branches grow from buds, buds are thus found in the nodes, whether or not they actually go on to grow a leaf or a branch.
Jujube nodes are unusual in that they contain two bud types: a main bud, and a secondary bud (Fig. 5):
And to mess with your head still more, whether such buds have strong or weak vigour determines the type of branch that will develop from them.
Pretty much every tree you’re familiar with has main branches and sub-branches that resemble each other despite age and location on the tree. But jujube trees really complicate things by having four different branch types: primary (extension) branches, secondary (non-extension) branches, fruiting mother branches, and fruiting branchlets!
The permanent primary extension branches are the ones that determine the shape and size of the tree. These branches are formed by terminal (end), strong, main buds which shoot each year and for many years to extend the tree’s overall structure and shape.
You can differentiate each yearly shoot extension along a branch — and thus age the wood — by its colour. Wood that grew two or more seasons ago is a drab grey-brown colour that becomes less brown and more grey with age. This wood also develops more furrows the older it gets (Fig. 6). (Thank you to Adrian for permission to use this photo!)
Last season’s wood is a smooth reddish brown. The transition between this and the prior year’s growth is very clear in Fig. 7 below. This wood will eventually become grey and develop furrows as it ages.
Current season’s growth is a bright green (Fig. 8).
The green will gradually change to the red colour of year-old wood by season’s end the following autumn. Fig. 9 shows this year’s growth on the Li of Fig. 3 above beginning to change colour at time of writing in late spring, 12th November 2019.
Some years later the terminal bud will weaken, the extension growth will halt, and a terminal fruiting mother branch forms instead of an extended branch.
Thus to summarise what we’ve covered so far: permanent branches are formed from strong terminal main buds, and fruiting mother branches form from weak terminal main buds.
Fruiting mother branches (not to be confused with fruiting branchlets, which we’ll get to!) aren’t only produced by terminal weak buds — they also develop from other bud and branch types which I’ll also get to — but let’s stick with the terminal buds for now as this is already getting complicated!
A fruiting mother branch resembles a pine cone. Like these two on the Ta-Jan in the earlier post that birthed this post (Fig. 10):
And these two on the same Li in Fig 3 above (Fig. 11):
And these two on Adrian’s Chico (Fig.12, and thank you again for permission to use this photo):
It is not at all obvious that these are branches, is it? Yet they are in fact very compressed shoots with several main and secondary buds on them. The (once strong, now weak) terminal bud of a fruiting mother branch grows ever so slightly each year, producing another cluster of buds that can produce up to ten fruiting branchlets in a whorl. The fruiting motherbranch is so named as it is the ‘mother’ of the fruiting branchlets, which are the dedicated branches for the flowers and fruits. The branchlets can vary from 100-300 mm in length (most fall within 120-250 mm in my experience), have alternating leaves on nodes 20-25 mm apart, and typically produce 3 or more fruits. These branchlets resemble compound leaves, but the presence of flowers and fruits show them for what they really are.
Fruiting branchlets are deciduous, and fall off by the following winter. On a small and young tree with little to no trunk/branch development, it is understandable to think your tree has died when you see every one of these little branchlets turn from vivid and healthy flexible green branches, to dried up, dead piles of brown twigs on the ground. Some branchlets do occasionally remain on the tree, but never grow again and come away easily if knocked or removed by hand.
Let’s revist the Ta-Jan. Below in Fig. 13 are the first and last photos of it in this post, side-by-side. Note how the main buds remained dormant while the secondary buds produced fruiting branchlets that growing season of 2017.
Yet the following year (2018) one of those main buds broke dormancy to produce this shoot, photographed on 10th November, 2019 (Fig. 14). You can tell from the red colour of the uppermost trunk that this shoot developed last season, in 2018. The secondary buds in the lower fruiting mother branches continue to grow fruiting branchlets — which are the same vivid green as all other growth of a current season.
If you go back to Figs. 11 and 12, you’ll see this exact same growth on the Li and Chico. That is, mother branches with secondary buds producing fruiting branchlets, but also where a main bud broke dormancy to produce a permanent primary branch.
But why did the Ta-Jan, Li and Chico all grow this way, while the Lang in Fig. 1 produced a permanent shoot structure from the outset? Here’s a close-up of the trunk of that Lang of Fig. 4 above, on 7th November, 2019 (Fig. 15):
You’ll see a fruiting mother branch at the junction where growth began in 2018. Unlike the Ta-Jan, Li and Chico, this branch simply had a main bud break dormancy in the 2018 season rather than this season 2019, hence the rapid growth readily apparent in Fig. 4. And while the Li in Fig. 4 put on its growth-spurt this year, the Lang has slowed in its extension growth, also shown in Fig. 4. It has instead developed more secondary branch structures.
There is already plenty here to digest, so I will describe these secondary branch structures and other peculiarities of jujube trees in a future post — and there is plenty more to describe when it comes to jujube branch development!
But to wrap up everything covered here:
Jujube nodes contain two types of bud: a main bud and a secondary bud
A bud may have strong or weak vigour, and this determines the type of branch that develops
There are four branch types: primary (extension), secondary (non-extension), fruiting mother branches, and fruiting branchlets
Terminal, strong, main buds produce the permanent primary branches, which ultimately determine the size and shape of the tree
Jujube wood is green in its first season of growth (less than one-year-old wood), is red during its second season (one-year-old wood), and subsequently browner then more grey and furrowed with each passing year
Permanent branch extensions cease when the terminal bud weakens; a fruiting mother branch develops instead
The (now weak, main) terminal bud of a fruiting mother branch will extend that branch’s growth slightly each year
Fruiting mother branches contain (usually) dormant main buds and active secondary buds that produce fruiting branchlets
A dormant main bud can break dormancy in a fruiting mother branch to form a new primary, extension branch