Ligules & Sabals causiarum, palmetto, domingensis/maritima

[PalmatierMeg]

There was a recent topic about IDing Sabal causiarum, that expanded to include other Sabals: palmetto & domingensis. I mentioned that my causiarum has prominent, papery ligules and the subject of ligules and other species of Sabal came up. Last night I photographed a number of palms on my world famous Sabal Row with a focus on which ones might have ligules. I posted the results below

Initial Photo: Sabal palmetto, front, Sabal causiarum, behind. Note the size disparity. I germinated the palmetto in 2008, planted it in 2009. I germinated the causiarum a few years later, so while it is several years younger than the rest of Sabal Row, it is by far the largest palm. The other large trunking Sabals have flowered for 3-4 years (we cut off their inflorescenses). The causiarum flowered for the first time in 2020. None of the much smaller palmettos has yet to flower at all.

Sabal causiarum: ligules circled. Another PTer informed us that not all causiarums have prominent ligules so I learned something new.

 

I choose the next two largest palms in Sabal Row. Their tags disappeared years ago but I suspect at least one of them might be Sabal domingensis or, perhaps, maritima. Maybe someone can settle their IDs. Both are quite large but no match for causiarum - and they are several years older. They have also flowered for the past several years. I found no significant ligules on either palm.

Sabal domingensis/maritima #1: no ligules

Sabal domingensis/maritima #2: no ligules

Photos below are of the three Sabal palmetto planted on Sabal Row. They were germinated in 2008, planted in 2009 but are midgets compared to the trunking giants around them. Sabal palmetto is the smallest of the trunking Sabals by far, the slowest growing and latest to flower for me. None of them has yet flowered.

Sabal palmetto #1: Are those little bits attached to the fibers just below the crown ligules? I think not but you decide for yourself.

Sabal palmetto #2: Even less

Sabal palmetto #3: No ligules

[mike in kurtistown]

Thanks for this information. This is what I like Palmtalk for, us helping each other out with the results of our experience and observation. 

[mike in kurtistown]

Actually, I took pictures of the ligules on my Sabal causiarums last January, may have even posted them. Seeds were collected in habitat by a palm colleague on a golf course in northwestern Puerto Rico, so the ID was known, as dominguensis is not present there. Pics below, the palms are not trunking yet, though their growth has been explosive.

 

 

 

[PalmatierMeg]

Great looking palm, Mike. They should be grown more often when people have space for them. My husband is indifferent to palms as a general rule, no fan of the Sabals but he loves this palm because it's so impressive.

[96720]

I have a palm that is supposed to be causiarum I was wondering if any body might be able to help me out 

[The7thLegend]

Excellent pics and observations PalmatierMeg

[SouthFLA]

Sabals hybridize very easily. I've seen sabals labeled incorrectly in more than one botanical garden but I won't name names. True causiarum will have prominent ligules and light green foliage. Domingensis has darker green foliage without prominent ligules and the trunk is less white but sometimes just as stout. Maritima seems to be a medium between the two.  Obviously there are other differences but this is a general distinction. A lot of the confusion comes from hybridization. Different characteristics from different parents. Always be sure the seed source was collected in habitat.

[mnorell]

17 hours ago, SouthFLA said:

Sabals hybridize very easily. I've seen sabals labeled incorrectly in more than one botanical garden but I won't name names. True causiarum will have prominent ligules and light green foliage. Domingensis has darker green foliage without prominent ligules and the trunk is less white but sometimes just as stout. Maritima seems to be a medium between the two.  Obviously there are other differences but this is a general distinction. A lot of the confusion comes from hybridization. Different characteristics from different parents. Always be sure the seed source was collected in habitat.

This was a major part of the discussion in another thread this last December...I had always thought the ligules were diagnostic, but Zona in his monograph differentiates by fruit characteristics and doesn't even mention the ligules that were used in O.F. Cook's original description. Apparently the ligules are found in certain populations in the Antilles but not others. From what I understand Puerto Rican populations typically have ligules while those from Hispaniola more likely do not. There are anecdotal identifiers often cited regarding large specimens, though these are not mentioned in Zona either...for one, that S. domingensis seems to hold a more or less full, spherical crown with some dead leaves at the bottom; while S. causiarum tends to drops them before they can hang down to the full extent. I certainly know that S. domingensis is much less leaf-hardy than S. causiarium. My S. domingensis in Natchez would always take heavy damage or even defoliate during a long, wet freeze to low 20s, while S. causiarum was happy as a clam. S. domingensis was  also much, much slower, though this could be because it was always just trying to regrow a crown every year, and thus had much less photosynthetic ability through the year.

As far as hybridization goes, I know that there are several "stable" hybrids that have been suspected over the years (such as 'Riverside' and Sabal x brazoriensis) but I was never aware it was a common occurrence, such as happens on the scale of, say, Veitchia. The paper by Douglas Goldman, et al., describing S. x brazoriensis found it to be a very old, stable hybrid of S. minor with S. palmetto (not S. mexicana as had been supposed); and noted that while S. minor is highly polymorphic it is genetically robust/stable and the only introgression involving other species are S. mexicana genetic influence in some Mexican populations of S. minor.  Here's the pdf of Goldman's paper.

[SouthFLA]

I respectfully disagree mnorell. Here's a pic I took with my wife and son yesterday of Sabal domingensis at Arch Creek park in North Miami, FL. There are 4 mature Hispaniola Palmetto just east of the main entrance. Growing behind them closer to the museum are a few hybrids (domingensis x palmetto). Go visit them and see for yourself. I agree that fruit is usually a good indicator but it is not always available for inspection.