This plant initially grew a set of leaflets, then it grew leaves with leaflets at the tips, and now its growing plain leaves. I've never seen anything like it. Can you please identify it for me?

When I enlarge your photos, they only get smaller, not larger. But, the only plant I know with this growth habit is Black Acacia (Acacia melanoxylon)

Yes https://commons.wikimedia.org/...
I was quite curious myself what it was..
Thought it was a fern...

That's a cool photo, but, according to the Catalogue of Life, Acacia facsiculifera doesn't exist.

Acacia melanoxylon is on the California invasive plant list.

"Catalogue of Life"...we both know i dont see eye to eye with those people..
or britton and rose..and some other authors that CoL encourages...
Ill stick to my ones..

Bajablue, I am 99% sure your plant is a Black Acacia. Location and growth habit both point me that direction.

Back story: This specimen popped up with a Golden Medallion tree I purchased from Evergreen Nursery in So. California.

I checked their website and they also sell ACACIA melanoxylon. (I wonder why a nursery would sell an invasive species?)

At any rate, while somewhat similar, the leaf/branch structure is quite different in composition. Here's a photo of A. melanoxin I pulled off the net.


I was able to find Acacia facsiculifera. This photo looks nearly identical to what is growing.



Looks like my mystery is solved. Thank you so much!

Come to think of it, Daisyl, I think you are correct. My tree is a mere seedling, which would explain the differences in structure. I guess time will tell.

There is no such tree as Acacia facsiculifera. There is only the one photo (the one Stefan posted) and it's only on wiki-sites.

It's ok to decide my ID is wrong - your photo is very dark. But it's not ok to decide it's a tree that only exists on wiki.

PS: The flat leaves on your little Acacia are called phyllodes - they are modified leaf petioles. Most Acacia have them at some point but, I chose an Acacia known to live in your area and also has wide flat phyllodes like the ones in your photo.

There are no laws against selling invasive plants, only conscience.