List of cold hardy trees with tropical looking buttress plank roots

[Iacób]

As the title says I'd like to know what large trees have large plank buttress roots that are hardy to at least zone 9a.

Edited March 23, 2025 by Iacób
I accidentally copypasted a thread to the wrong forum, so I decided to edit it into a different topic

[John2468]

I can only find two: Ceiba speciosa and Ficus macrophylla. I’m sure there’s more out there that are rarer. Hope this helps

[Iacób]

Thanks! And I did find another tree, the Laurelia Novae-Zelandiae, also called the Pukatea tree has large plank roots.

[Rivera]

Metrosideros excelsa aka Pōhutukawa or NZ Xmas tree exhibits vigorous root development both subterranean and aerial. Once the trees get big enough (maybe 20-25 ft tall), they start to send down aerial roots from their branches. Given the roots reach suitable ground, these develop into buttresses to support the main trunk, into which they may eventually merge if the tree is allowed to grow large enough. 

This is the most common street tree grown in my neighborhood (San Francisco, 10b by the water), and while most of them are under 30 feet, they can get much larger than that and are best given a lot of space.

It's a 9a-ish plant I believe, though online resources differ somewhat on this. Like bunya bunya or other tropical-ish trees grown here, it may be sensitive to frost when young. 

An image search on this forum will provide some photos if you're unfamiliar. 

[Iacób]

Thanks!

[Than]

On 3/25/2025 at 4:16 AM, John2468 said:

I can only find two: Ceiba speciosa and Ficus macrophylla. I’m sure there’s more out there that are rarer. Hope this helps

Are you sure these two are hardy to zone 9a? In Greece you only find them in zone 10a and above. 

[John2468]

11 minutes ago, Than said:

Are you sure these two are hardy to zone 9a? In Greece you only find them in zone 10a and above. 

According to the internet, I’m not very good with trees.

[Silas_Sancona]

1 hour ago, Than said:

Are you sure these two are hardy to zone 9a? In Greece you only find them in zone 10a and above. 

Can't speak for F. macrophylla  but there are long term Ceiba speciosa planted in a few 9a areas here. Numerous specimens of it planted in 9B areas in California, S.Cal esp.

 

[Than]

57 minutes ago, Silas_Sancona said:

Can't speak for F. macrophylla  but there are long term Ceiba speciosa planted in a few 9a areas here. Numerous specimens of it planted in 9B areas in California, S.Cal esp.

 

I see. I must confess there are too few specimens here to draw conclusions. I can't say the same for F macrophylla though. They are common in zones 10a and 10b but have never spotted any in zone 9.

[richtrav]

These are a decent sized pair of Ceiba speciosa in July of 2021 after about 21-22 degrees in February. Ceiba pentandra makes more impressive buttress roots but is more tender.