Sabal domingensis with ligules?

[Phoenikakias]

I am admitting having little experience on genus Sabal, as specimens in in Greece are few and mostly not public.  Therefore I am calling to help @sonoranfans. 

It is a widespread belief that ligules of leaf sheaths are a very important diagnostic for S causiarum and a distinctive feature of former from the related S domingensis.  However the valid and undisputed differentiating feature is the shape and size of fruits and seeds. Namely fruits and seeds of domingensis are larger and fruits also have a pyriform shape in contrast to generally round or occasionally pyriform fruits of causiarum.  in detail diameter range of domingensis fruits is between 11.5 - 14.1 mm vs 7.1 -10.8 mm for causiarum and regarding seeds 8.0 - 10.4 mm vs 5.9 -7.8 mm respectively.

This summer a Sabal specimen of mine with very long such ligules and thus thought to be causiarum bloomed for for the first time and set fruits seem being up to now pyriform and most importantly size extends slightly beyond the valid upper limit for causiarum. On the other hand fruits are still green and I am not sure whether seeds will dehydrate a bit by maturity and their size will be eventually reduced. In detail diameter (without use of the special tool) of fruit is about 14 mm.

Here is some pictorial documentation. The fruits and seeds of my plant are always directly next to a bigger fruit and seed from a specimen thought be S rosei.

[Phoenikakias]

Hmmm, I omitted writing that diameter of seeds  is 8 mm, marginally longer than the upper limit of causiarum.

[sonoranfans]

While many causiarum are reported to have ligules and most other sabals do not, I have not heard of anyone on this forum growing domingensis, it seems rare in cultivation.   Part of that could be if a grower wanted a cold hardy palm and selected causiarum for its 15F or better cold hardiness, the domingensis will not survive their climate.  My causiarum developed smallish ligules(12-15") just prior to flowering, it was already trunking.  The ligules on mine are relatively short and look more like partly dead(brown) material.  Some on this forum have shown ligules in excess of 2' all green to the tip.  Scott Zona -in his 1990 monograph on caribbean sabals- offered the orders of branching of the inflorescence as definitive between causiarum(3 orders) and domingensis(4 orders).  Zona went to habitat and saw many palms of both species of course for his research.  My causiarum was bought as a domingensis so it took till inflorescence until I could identify it by Zonas' method.  I understand that these species have been mixed up quite a bit by botanists.  I think Zonas work allows that separation.  The mis ID of these species was attributed  partly to a large palm grown indoors in Germany(?) in a public garden.  Botanists said the palms grew different morphological characteristics at that site and I expect growing palms from desert to tropics also leads to morphological plasticity.  When I took a look at your fruit and seed sizes and compare them to mine, I thought about that plasticity of the morphological features that can arise in different environments.  My fruit and seeds appear to be in the lower end of the range reported(7-10mm and 5-7mm).  I would just take a look at the inflorescence branching, ID solved.

[LeonardHolmes]

Here are the ligules on my S. domingensis bought a while back from Gary's Nursery.

(I damaged it a bit by using "Sedge Hammer" on a colony of nut sedge that was under it.  The lowest petiole you see is yellowed curved in a manner unlike the others on the palm.)

I planted a clump of sabals together in 2021 and the domingenis is taking over.  There is a North Carolina Sabal palmetto behind it, a Birmingham, a S xbrazoriensis, and another that is a mystery to me (labeled S uresana).  The form on that last one is petite, like a minor, but the seeds are way too big. The picture of newly planted palms is from June 2021

These survived 18 degrees F.  I documented that temperature for the S. domingensis in this post and there is a picture of it from early 2023.