Hey! I don't really know any difference between they two (therefore I won't be much help), I am just wondering: Where are you thinking of putting all these palms? I have seen many of your previous posts and you seem on the verge of accumulating a huge collection of palm seedlings!

I'll put some in my yard, then my family has some land that we put them on. We are actually trying to make a subtropical themed forest in about 4 archers of land. We have been building on to this for years now.

seeds are identical... will never be able to tell them apart that way. In nature, Washingtonia robusta is a far faster grower, with a thinner trunk, smaller, greener, bushier and more compact crown of leaves and usually less fiber on the leaves. Washingtonia filifera grows a huge, stout, pole-like stem that is straight as a column, which robusta often develops an attractive curve in its stem (in about 30-50 years). Petioles are green with a lot of dark brown to reddish brown on their bases, while filifera petioles are usually pure to nearly pure green their entire length. Washington filifera leaves are a slightly pale green to sea green (at least in the mature palm), while robusta leaves are a bright, shiny, deeper green (this difference not too obvious in young palms).

many palm specialists consider the two the same species but variations on the species, due mostly to their different populations origins... but not all taxonomists agree with that assessment.

As I understand it, most of the adult specimens available in the East are actually the hybrid, Washingtonia filibuster. Pure filiferas are much slower growing, have more fiber on the leaves, are cold hardier, and are have stems that are less reddish. Washingtonia robustas have less fiber, are faster growing, have reddish thunks, are less cold hardy but are hardier in terms of tolerance to heavy rainfall and tropical humidity. Filibusters are somewhere in between. Life is complicated, I guess.

Filifera tend to have a kind of dull hazy green foliage, where Robusta has more of a brighter green foliage.

I am a fan of the slender sort (Robusta) of Washingtonia; I like the skinny look for some reason.

Ok, thank you all!

If you can, there is a petition my friend found on to attempt to save U.S. native palm trees. Anyways, here is the link.

https://www.change.org/p/united-states-department-of-agriculture-usda-preserve-u-s-native-palm-trees

There's an interesting page that speaks experience:

http://palmvrienden.net/gblapalmeraie/2017/07/05/how-to-recognize-the-difference-between-washingtonia-filifera-and-robusta/#comment-757