It's Filifera or Filibusta.

I got a robusta off of ebay once and it looked just like yours. However, I think that mine and yours are both filibusta.
-Alex

You got me on the id--? I have several like yours that were sold as Mexican fans (W. robusta). Assumed they were based on growth rate, trunk coloration, limited fibers, etc.., but saw some pics on line that showed similar ones listed as "filifera". I suspect pure filiferas are rarer in the East as they tend to resent HUMID climates (and most sold in the East are coming up from Fl.) You're in Wa and filiferas I imagine, are more available from Ca. I think we both probably have filibusta hybrids--hopefully they have some of the best traits of each. I can post some pics of mine to add to the confusion. :)

@njoasis yes please post your pics for comparison. I was thinking it is a filibusta too. Which I am happy as we can get below 20* on any given winter however going below 20* at night does not happen every winter. Of course it did in a big way last winter (mid and upper teens for 2 nights). Good for an established filifera trait. Even though out summers are dry our fall especially late fall and early winters are pretty wet and cool. That's where the robusta trait would help.

In read today on a European palm board where someone questioned filifera's so called humidity/moisture sensitivity. That person went on saying he believed they were pretty sensitive when young (i.e. seeds and under a year old or so) but were not as effected when older. I don't know how true that is so if anyone wants to chime in on that one go for it. I plan on buying some filifera seeds off of ebay this weekend to grow since they are my fav washingtonia.

Years ago, I purchased seeds that were identified as both W. filifera and W. robusta. Only the robustas survived and continued to the present day--pure filiferas all seemed to die out over time. Some of my current collection of Washingtonias were seed grown, one brought up from Miami, and a few supermarket bought locally (which was unusual because neither filifera, robusta, nor filibusta tend to be sold locally)--too prickly for the average house and not Winter hardy in zone 7 (without protection). All were labeled Mexican fans (W.robusta) but as I say, I suspect some may be filibusta, but I doubt I have any pure filifera. Filifera may well do fine for you in the Pacific NW (or Europe for that matter) where most areas are warm and relatively dry in the summer. I suspect that it's high temps combined with humidity that they might resent. (I would be interested in knowing if any healthy filiferas are grown in South Florida.) In any event, I have more than enough Washingtonias already as they just DON"T DIE--even after spear pull! :) By the way, another palm from an arid region has given me problems over the years. I've tried growing True Date (Phoenix dactylifera) a few times unsuccessfully. Have no problems with other Phoenix species. But I am giving this one another chance. Am growing the current one in a very coarse mix. Monsoon season has just started here so won't be able to post pics until Tuesday . But what I want to do, is to select my most robusta-like Washingtonia and the most filifera-like one in order to get better identifications from the experts out there.

This comparison between filifera and robusta is interesting :

http://www.floridata.com/ref/w/wash_fil.cfm

But it also confuses me because filibusta is not compared. And I'm confused with the baby Washingtonias I collected in a friend's San Diego garden. She has no Mexican fan palms because of the neighborhood association requirements to keep their dead foliage trimmed off. She calls them "weeds" so I rescued several ranging In size from single strap seedling to a foot and half tall one with full and fuzzy fans. Four survived the dig up, transcontinental flight in my checked bag and repotting at home.

The largest definitely has green petioles and thorns. Floridata site above says filifera has green petioles and no thorny teeth when young, but the robusta are supposed to have a more reddish petiole with thorns. And leaves have plentiful filiments.

Could mine be the hybrid filibusta? Are they common "volunteer weeds" in SoCal?

Hey Earthworm, I read on Wikipedia that "stores don't sell purebreds (filifera or robusta), they only sell hybrids (filibusta)." That may answer your question, provided you trust that source.

http://en.m.wikipedia.org/wiki/Washingtonia_filibusta

wetsuiter you probably have a "pure" or very close to pure filifera as you can get. I have never seen pics of pure filifera without some sort of teeth. Must be nice to have a friend down in Cali with this "weed problem". BTW you mind parting with one of those small ones?

Mine does have teeth ( or thorns as I was calling them), hence my confusion. The petioles are green, it has teeth and fiberous fans.

The two little ones are still "iffy". Hope they're making roots. Will advise. Not sure another transcon flight will help them any right now, especially as freight.

As far as I'm aware, BOTH filifera and robusta have those thorns so don't know if they are useful in distinguishing them. Robusta are said to have a more reddish trunk, and while they also both have fibers, filiferas are fuzzier. Rosbusta growth is said to be faster. Also, keep in mind the central feature that botanists use to determine species relationships--flower structure (don't know if they are significantly different in this respect). And speaking of botany, given that filibusta is a hybrid, I assume its seeds will be sterile.

I don't know that all hybrid palms are sterile, but it's an interesting point worth researching. If filibusta are indeed sterile, mine could be one as it probably grew in my friend's garden because a bird dropped the seed and there are no washys near by. I would have been gathering seeds otherwise.

It's true that both mature filifera and robusta have teeth on the frond stalks, the Floridata site comparison states that YOUNG filifera do not have teeth, whereas young robusta do. At what age / size do teeth start to appear on filifera? No clue. My Washy that has teeth is only in a 6" pot and has teeth, so I'm guessing it's still considered "young", so probably is robusta.

Filifera thorns are smaller/less obvious but there to be sure.