Causes of leaf shape variability

[Kelby]

There has been much heated debate, bad deals, and so forth stemming from the use of leaf shape to ID fig varieties. I do not want to delve into those experiences too much and renew any arguments over whether or not a plant is true to name.

I have been pondering the influence of epigenetics as a cause for leaf shape variability, specifically when there are 2 plants that should be same variety but exhibit different leaf shapes. A brief summary of epigenetics is that chemical, environmental, or other forces can cause changes in genetic expression (turning genes on and off). It has already been documented that external stimuli can alter leaf shape on hollies (http://news.nationalgeographic.com/n...lants-science/) and other plants (https://books.google.com/books?id=YL...0shape&f=false). Evidence suggests that such changes can exist for varying lengths of time, and some can be reproduced in following generations.

So my hypothesis is this: there is some stressor on a plant, let's call it Fico Epigentico in Person A's collection in California. Person B also has a lovely Fico Epigentico in New York that came from Person A's 2 years ago before there was a drought and someone got a little too close with the herbicide last summer. Person C grows cuttings from both in Texas, but the two Fico Epigenticos don't look the same! Perhaps, sometimes, these changes in leaf shape can be explained by these epigenetic changes.

Thoughts?

[Harborseal]

It's definitely a possibility but it doesn't necessarily explain 2 close branches on the same plant that have entirely different leaf shapes

[mountainfigs]

The shape of fig tree leaves tends to vary, especially when the tree is young. Variations can be branch to branch or tree to tree. Often, variable leaf shape is due to the fact that during rapid leaf growth, leaf margins tend to be more defined, lobes sometimes more numerous than on the slower growing leaves. Leaves that get less direct sun than other leaves on the same tree tend to have a different shape, more simple and/or relatively broader lobes, and so on.

[Rewton]

Rusty, as I eluded to below, my CdDN is doing the same - part of the tree is single lobed and part is multi-lobed.

[seyagi]

Agreed. I think maybe both are true, but I constantly see different leaf shapes and (even more importantly) growth habits from different cuttings off the same tree. Without fail, cuttings of different limbs tend toward different growth habits. Cuttings taken from more shaded, lower branches that aren’t from main scaffold seem to grow slow for me. Rejuvenation pruning is the remedy for this. Non apical cuttings from main fruiting branches in the fall are usually on point. Apical cuttings continue to be a mixed bag. Just my experience.

[Rewton]

I have wondered about (and have posted about) this very idea but for cold hardiness, not leaf shape. In your example, the person in Texas might find that the variety derived in California is less cold hardy than the one from NY (although more than 2 years might be required for adaptation). I agree that it could be epigenetics that causes differences in leaf morphology. I've also heard that the rate of growth influences this with fast growth favoring fewer lobes (or is it more?). I have a CdDN that is in its 2nd full season and has finally switched over from single lobed leaves to the more typical multi-lobed leaves of a Col de Dame which is what the mother tree had when the cuttings were taken. The mother tree is about a 2 hour drive away and there isn't any obvious environmental conditions that might cause differences in epigenetics. But I hear what you are saying - when you look at how some varieties, and how people swear up and down that there are no mix-ups, but you see such differences in morphology it makes you wonder if they really are true to type and there are other factors at play. My Genovese Nero from a trusted source has several different leaf types by the way...

[Kelby]

The hardiness thing is true. Miller Nurseries used to claim their plants were tougher being grown in upstate NY. I read a study showing their premise was correct; the same varieties in different climates will develop different hardiness. I'd presume it's from epigenetics.

[mountainfigs]

I hope that this effect, or mere maturing, allows bushes that I try to preserve as low limbs over winter to toughen up in a few years so that they might come through winter with less mulch protection, or so that any mistaken gaps in protection are not as damaging as they might otherwise be.

[AscPete]

IMO, Anything and everything causes leaf shape variability.
Temperature, light, water, nutrients, growing medium, cultivar health and cultivar type, but the variability is usually within a certain range of shapes.

[mountainfigs]

The epigenetics explanation sounds entirely reasonable.

That said, comparing any single plant to any other single plant, let alone one shipped across a continent, is fraught with all sorts of possible, even likely, complications. Anyone who has persistent doubts about the nature of the cultivar they are growing needs either to refer to authoritative research or to compare the plant to a number of specimens of the cultivar, more than a few if necessary and preferably to specimens grown under similar conditions to the plant in question.

A pattern of epigenetic effects would need to be observed in multiple specimens before any single specimen could be concluded to be likewise affected, which takes you back to referring one specimen to a group rather than one to one.

[rusty hooks]

Here's a question....an air layer, taken on the single lobe leaf side of the tree, would be expected to provide another, single lobed leaf tree...correct? Or..does the single lobed section of the tree still hold the genetic stability and prescence to throw a lobed leaf branch off the air layer.....a project ensues...

[AscPete]

No, usually the trees will produce the other leaf shapes later in its growth. There are several cultivars that have this characteristic, Aubique Petite and Strawberry Latte are two of the more well known.

[eboone]

Strawberry Latte? Or the Raspberry one

[AscPete]

Ed,
Sorry, yes Raspberry Latte....

[Dale_M]

Salce, too. I have one that has no lobes on leaves on primary leader. Now suckers are coming up with an entirely different leaf shape.

[AscPete]

Attached are photos of "Leaf Variability" of an Italian Honey cultivar. The older single and three lobed leaves were produced from older wood at a slower growth rate. The newer multi-lobed leaves were produced on new faster growing branches closer to the soil line. From my observations this is typical leaf variability for most fig cultivars, faster growth (longer nodal spacing) equals increased lobes or crenation (scallops). The different leaf shapes are still all within the range of possible shapes for this cultivar.

[HarveyC]

I have two Socorro Black trees started from cuttings obtained from Jose (the discoverer). In 2014 I had concerns about a mix-up since the leaves did not seem "right" even though trees were of good size (5' tall or so). This year, the leaves on both trees look "right". Attached are photos of long-fingered leaves from 2014 and a current photo. I don't know what to make of it. I started a thread about this topic at F4F last year and it got heated. I asked my agronomist (with lab I'm working I'm using) about this topic two weeks ago and he did not believe nutrition should affect leaf shape. Zinc will increase leaf size but he did not believe the shape should change but said he might research it some.

[HarveyC]

The available nutrients in my orchard is much higher this year than last, without a doubt. I've been applying quite a bit of CAN 17 and KTS this year with extensive monitoring of soil solution and leaves by my lab. I'm not seeing the increased finger like leaves.

[AscPete]

Another reason (variable) why they may not be presenting themselves is that there is more 'old' wood. The proximity (distance / location) between the roots and the new branches and leaves is another variable that influences the leaf shapes. As noted in post #9.

[HarveyC]

The trees are obviously a year old but, as I previously wrote in post 10, the trees were already pretty good size last year. I pruned the branches to my wires like I did the year before so trees are about the same size this year. I think it's a mystery and that figs do this to cause humans to scratch their heads.

[AscPete]

Note the attached photos of VdB EL the less defined leaves are produced on slower growing branches (close internode spacing) while the more defined digitate leaves are produced on fast growing branches.

[AscPete]

Leaf shape changes due to Winter dieback, new growth closer to soil line...
The pictured trees are both Unknown TimLight in the Bronx NYC.

[azhark114]

I was wondering if anyone has seen the following, variety Olympian fig zone 6, two different leaves shapes.

[Rickyv101]

Your tree looks like VDB/negronne. mis-label?
in your area, I think that Olymipian will be English Brown turkey leaves. It is strange that it has long finger leaves at PNW.

[AscPete]

That definitely is VdB type cultivar...

[seyagi]

The application of epigenetics is fascinating in figs because we can see these apparent expressions within a couple of years in some cases. Almost like fig trees are the perfect subjects for these studies.