Rachy Ramone's picture

Juglans nigra - Black Walnut

Observed: 1st November 2012 By: Rachy RamoneRachy Ramone is knowledgeable about PlantsRachy Ramone’s earned reputation in PlantsRachy Ramone’s earned reputation in PlantsRachy Ramone’s earned reputation in PlantsRachy Ramone’s earned reputation in Plants
1211 Juglans nigra part of leaf
1211 Juglans nigra leaflets
The size of tennis balls. Real ankle-snappers.
fruits attach sideways!
Description:

Large, stately tree, very decorative: fruits are as big as tennis balls and are attached sideways on to the stem, singly or in small groups. They have a very distinctive sour smell.
Leaves are very long pinnate leaves with lots of "pairs" of leaflets - they are often not quite opposite each other, as can be seen in the first photo, of part of a leaf.
The leaflets themselves are longer and thinner than those of Common Walnut (Juglans regia) which is often found planted along paths and hedgerows.
Books always say that walnuts secrete a chemical which prevents other plants growing around them. This is simply not true, I am constantly weeding under this one (!) and every Common Walnut I have seen in hedgerows etc has the normal undergrowth around it, right up to the trunk.

Identifications
Species interactions

No interactions present.

Comments

markwilson's picture

black walnut

I went past one of these for years without noticing it wasn't an ash! \until my wife asked me what the plant was because of its fruits. Tomatoes in particular are supposed to not grow near it

Rachy Ramone's picture

Tomatoes...

Mark, I've never heard that before: why tomatoes in particular, I wonder?

I have to say, the smell of the walnuts and the mess they make on the ground would prevent me from ever wanting to grow edibles under a walnut tree. But I don't know if there's any "real" reason for that supposition.

*rolls eyes* I suppose that next year I am going to have to plant out some toms, to see what happens!

I have suspected that a lot of the suggestion of "they stifle other growth" is merely from the shade that they cast, although they are not what I would call a heavy-shade tree. Like Ash, which they greatly resemble, from a distance!

*pause while I google it*

Errrr.... "Black walnut trees produce a toxic material (juglone) that can injure and kill solanaceous crops (tomatoes, potatoes, peppers and eggplant)"

OK, next season, I will do an experiment. I'll let you know the result!

Rachy Ramone

How to take close-ups with cheap phone and hand-lens:
http://tree-and-shrub-id.blogspot.co.uk/p/how-to-close-ups.html
Field Guides for Budding Botanists:
http://www.amazon.co.uk/-/e/B01A8YB0WY

lavateraguy's picture

Another word for you to learn

Allelopathy. Walnut is fairly well known as an allelopathic tree.

Rachy Ramone's picture

Aha! I already knew that!

I'd already come across this one!

It seems quite a limited phenomenon in trees - mostly Black Walnut, along with Ailanthus altissima, and some Eucalyptus species. It's an interesting concept, and makes perfect sense.

Can't wait for the leaves to come back, now, as I have planned out my experiment for next year, to test Black Walnut for myself!

I shall also be paying particular attention to what is growing underneath the trees mentioned, to see if there is indeed any sort of restriction on what grows there.

Rachy Ramone

How to take close-ups with cheap phone and hand-lens:
http://tree-and-shrub-id.blogspot.co.uk/p/how-to-close-ups.html
Field Guides for Budding Botanists:
http://www.amazon.co.uk/-/e/B01A8YB0WY