That's Washingtonia robusta, the Mexican Fan Palm.
Washingtonia filifera is a much more robust plant, not as tall growing, hardier to cold, much nicer looking (IMO), but it is more susceptable to wet then is robusta. If yoyu travel to the US southwest (i.e. St. George Utah) in the spring you can clearly see the hardiness issue illustrated, the robusta will be tattered and brown, while the filifera will have complete crowns. Here is a picture of filifera in habitat (Moapa, NV, fall 2008):
<img src=" " alt="Moapa4">
<img src=" " alt="Moapa3">
Just so you know, coming across a 'true' W. filifera in the Eastern USA is not common. It is far more likely to the W. x filibusta, a hybrid between the two species, which is intermediate in hardiness. If the palms are tall they're easy to tell apart by looking at the trunks, which are MUCH thicker in filifera; other methods, such as a more 'purple' trunk in robusta, and excess filaments in filifera are also used.

That's a cross or it's filifera. 😀

On second thought, they are both a x, one more on the robusta side and the other more on the filifera side. Filifera has bluer leaves, larger crown, larger trunk, longer leaf stocks, less or no red at the base of the leaf stocks.
Just like Paul said. 😀

I don't know... I still say they're 'robusta'...

Robusta-like traits:
1. The trunk is more 'purple' in colour and looking at the first photo you can see a bit of purple on the petiole, which is not present in filifera.
2. The base of the trunk has a swelling which is characteristic of robusta.
3. There are thorns on the petioles (minute or not present in filifera).
4. The leaflets, though 'hairy' are not as hairy as you'd expect in filifera (filamentous)

Here is an easy experiment we can use to decide the species (and they say cold tolerance can't be used as taxonomic trait!):
We expose the palms to 22f for a while:
If the leaves brown then it is robusta.
We expose the leaves to 18-19f for a while:
If they brown then it's x. filabusta

Otherwise you have pure W. filifera!

Perhaps you can just label them 'Washingtonia palm' that way you don't have to be exact! And it's silly to argue about something as inexact as the 'true' taxonomic placement of a species, it's all based on someones opinion and some phenotypic traits that may or may not have any real meaning... And this coming from someone who does this stuff for a living... ugh.

I agree they are Robusta. Robusta have that taper to the trunks and the maroon color at the base of the petiole. Filifera have much fatter trunks without the maroon coloring at the base of the petiole. Heres a nice example.

The trunks of these palms are already twice the size of any pure Robusta,even(esp) the ones that are close to a 100' tall.

The trunks of these palms are already twice the size of any pure Robusta,even(esp) the ones that are close to a 100' tall.

I agree, they are without a dought a X. Look how long the petiole are, and how blue the leaf looks. The crown is twice the size as a robusta would be. 🙂

Sure you're not counting the boots? They make a trunk appear quite a bit thicker than it really is, remember that 'pure' robusta has a bare trunk diameter of up to 14-15" (wider at ground level, ie. the little plump bulge which is a character not found in filifera), which based on the picture provided I feel is not surpassed... Maybe our friend can tell us how thick the trunk is with the boot attached?
Some pics of smaller robustas (From palmco.com):

And here is one that shows what I'm talking about with the boots:

I agree with you also, they are robusta, just ones that have crossed with filifera. 😐

Very funny! Good answer. 🙄

Ya, I gave up when I read that...

I made my argument and gave reasons why I feel that the palms in question are not filifera or hybrids!

Very funny! Good answer. 🙄

😆

Ya, I gave up when I read that...

I made my argument and gave reasons why I feel that the palms in question are not filifera or hybrids!

:hiding:

I keep reading that Robustas are have skinny trunks. Less than twelve inches. The base of my Washys are much bigger and they're not even that old. Some of the others they were selling had trunks of at least two feet.