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UltravioletPhotography

Golden Chain Tree?


Andy Perrin

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Andy Perrin

My step-mother has this tree growing in her garden in Gloucester, Massachusetts. She said it was either a Golden Rain Tree or a Golden Chain Tree (Laburnum Anagyroides). It looks more like the latter to me.

 

I put the "arty" photos up top, and some general shots of the tree and foliage down below. If we can definitively ID it, I'm open to making a more formal post of this. For now, accept this artistic rendition, which has had the colors saturated up quite a bit, and a slight white balance shift applied. I did make a Teflon WB and I have the original RAW, so it can be standardized later if need be.

 

Visible reference image (iPhone 6S Plus, and some Photoshop contrast/tone adjustments, overcast sky/indirect sunshine)

post-94-0-05101000-1496030815.jpg

 

EL-Nikkor 80mm/5.6, F22, 20", ISO200, saturation and contrast adjusted, and then denoised and sharpened. Filters were 1.75mm S8612, and 2mm UG11 (or clone of it)

post-94-0-85426100-1496030954.jpg

 

(Same settings and processing as above.)

post-94-0-33554800-1496031107.jpg

 

Some snaps of the tree itself:

post-94-0-32362200-1496031148.jpg

 

Flowers as they look on the tree:

post-94-0-84077100-1496031180.jpg

 

Leaves:

post-94-0-44145200-1496031201.jpg

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Yes, that is a Laburnum, a member of the Pea Family (Fabaceae), Golden Chain Tree. (They are toxic, so handle with care!) I don't know the Laburnum species, so you'll have to investigate that.

 

The UV photos are quite interesting (and very well made). Fabaceae flowers always show interesting markings in UV.

 

I always think of Fabaceae as plants or vines like peas, beans, lupines, sweet peas, gorse, etc. and forget that there are Fabaceae trees like this one or like Robinia (locust).

 

As always, I would love to see any member's UV botanical photos posted in our formal botanical section.

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This is a representative of the genus Laburnum, a small genus originating from central Europe.. Although they are not native to my country (Norway), two species (L. anagyroides, L. alpinum) are commonly planted and becoming naturalised. Both have toxic seeds. However, in the last decades, most ornamental Laburum is the hybrid L. x wateri which still is toxic but most seeds abort early so its potential damage is minimal.

 

The specific identification is difficult, in particular of the hybrid and L. alpinum, because all these species are actually very close. One needs details such as whether leaflets are silky haired or not on their underside, hairiness of young branches, the appearance and colour of the fruit pods, and the colour of the seeds.

 

Your plant is probably not L. anagyroides, because the flowers lack the extra markings typical of that species. Thus two candidates remain and the hybrid is the more likely of these. However, a valid identification requires the details I outlined earlier.

 

Nice UV photos, by the way. My Laburnum captures look the same.

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Andy Perrin
Thanks, Andrea and Bjørn. I passed on the information about the toxicity to my step-mother, who has two chihuahuas who could potential eat the seeds. I'm not visiting again for a few months, so probably I won't be able to make a formal post of this since I don't think I can gather the requisite information at this point.
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Andy, you can post it anyway (and please do!) using this post title: Laburnum sp. [Golden Chain Tree]

And in the ID string (first line) within the post use this: Laburnum sp. Fabr. (Fabaceae) Golden Chain Tree.

 

When we do not know the species but are sure of the genus, then the "sp." is used after the genus name as accepted botanical practice.

 

In your comment you can use the info Bjørn has provided about the species possibilities. The Wikipedia entry also covers those. I think that your post belongs in the Cultivars section because in the US these trees are not natives.

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Andy Perrin
It's interesting, my UV signature does not look quite like EITHER of the two linked laburnums — mine has some purple on the corona (if I have the jargon right). I will start on a formal version, Andrea.
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Bjørn, didn't see your follow-up post. Nice Laburnums! I remember seeing one of these trees in Oslo when we were walking around downtown. I'd never seen one for reals before and was fascinated with it. (Sign of a True Nerd -- she gets fascinated by plants!!)

 

Seeing Bjørn's Laburnum UV shots and comparing them to Andy's Laburnum, I think we might be able to say that Andy's Laburnum is probaby L. anagyroides because the pea flower Andy shows has dark false colour on the wings of the flower and the other two examples do not. So I think we could recommend to Andy that he title & ID the post as:

  • Laburnum cf. anagyroides [Golden Chain Tree]
  • Laburnum cf. anagyroides Medik. (Fabaceae) Golden Chain Tree

Andy, the 'cf.' notation is used when you are fairly certain -- but not 100% certain -- of the species. (Note change of botanical author.)

 

The parts of a pea flower are: banner, wings and keel.

The banner is the big upright petal. The wings are the two lower petals which surround the pointy keel thing.

 

Bjørn, do you concur with my recommendation for Laburnum cf. anagyroides ?

 

EDIT: No, he doesn't. So we stick with the 'sp.' designation.

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I beg to disagree. L. anygyroides should have darker spots on the corolla in visible light. We have no information how reliable that character is, though.

 

I want to see whether the leaflets are densely silky hairy on their underside before accepting the suggestion of L. anagyroides.

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Andy Perrin

I'll put it as (sp) until I can check in July.

 

I think we might be able to say that Andy's Laburnum is probaby L. anagyroides because the pea flower Andy shows has dark false colour on the wings of the flower and the other two examples do not.

I think that's kind of a non sequitur? That would only follow if there are exactly three possible species, and the coloring reliably corresponds to the species. (Human beings are all the same species and even WE do not all have the same coloring!)

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OK, I get it. :D

Stick with the 'sp.' suggestion.

 

But that UV signature is very interestingly different from the other two.

And the wings are more tightly wrapped around the keel.

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Andy Perrin

I beg to disagree. L. anygyroides should have darker spots on the corolla in visible light. We have no information how reliable that character is, though.

The plot thickens...

post-94-0-86242800-1496086278.jpg

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Those spots definitively look more anagyroides, agreed. But given the complexity of the taxonomy in this genus, please provide close-ups of leaflets (underside) and young branches as well. The pods are also important.
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The only Key I could find was in Swedish on the website Den Virtuella Floren. And this key does not include the hybrid.

 

Laburnum alpinum: Leaf bare, i.e., hairless. Seed pod with winged edge. Seeds brown.

Laburnum anagyroides: Underleaf hairy. (Abaxial side of leaf). Seed pod without winged edge. Seeds black.

 

Laburnum is named "gullregn" in Swedish - meaning Yellow (gul) Rain (regn).

Although I suppose the 'gull' could derive from guld (gold)? Bjørn?

 

The key:

 

1. Blad kala. Fruktbaljor med vingkant. Frön bruna.

---alpgullregn (L. alpinum)

1. Bladundersida hårig. Fruktbaljor utan vingkant. Frön svarta.

---sydgullregn (L. anagyroides)

 

LINK: http://linnaeus.nrm....ur/welcome.html

 

I've been thru so many keys now that I didn't even have to look up any words except for 'gul(l)'. "-)

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'Gull' in the Swedish text denotes 'gold' ('gyllen' is 'golden'; 'gul' is 'yellow'. That completes the Crash Course in Swedish :D ) Thus its common name in Swedish (and, incidentally, Norwegian and Danish as well) means 'Rain of Gold'. Very poetic and describes well the appearance of these small trees when they come into blossom in the late spring.

 

The Swedish key quoted by Andrea basically separates them on the hairy leaflet underside, wingless pods, and black seeds (anagyroides) vs glabrous undersides of the leaflets. winged pods and seeds with brown colour (alpinum). The hybrid is referred in the text; it is (surprise) intermediate in these characters.

 

I have a complete Laburnum key in my big Norwegian flora, plus in Flora Europaea.

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