Spear Tips On Most Pinnate Crown Shaft Palms And Some Non-Crown Shaft Ones.

[Jim in Los Altos]

Anyone here know if there’s an actual name for the bit of brittle growth at the top of many pinnate species, particularly ones with crown shafts? And what its purpose might be if there is one. As you can see in my video, these snap off quite easily and fall away on their own too. The palm in the photos is a common volunteer in my garden, Archontophoenix cunninghamiana and I see this spear tip characteristic on lots of my other palm species

 

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Edited October 14, 2023 by Jim in Los Altos

[James B]

Great question. Hopefully someone more knowledgeable than myself will chime in. My guess is so the new spear is encased so it does not damage the inside of the existing crownshaft as it emerges while also protecting the new leaves until they are ready to open. But I could be wrong. As for the name I too would like to know if there is an accepted anatomical term for it. 

[Kim]

Interesting question. On many Chrysalidocarpus, there are long strips that hang down, referred to as "reins," which come from a sort of "zipper" along the leaflets that drops off when the spear opens. I've noticed sometimes a more blunt section at the end that might be that same piece from the tip of a spear.  Just speculating. On some palms that hard bit keeps the leaflets at the tip of the frond together longer than seems necessary, notably on my Howea palms. I wonder why it happens, but I don't mess with them. Maybe Scott Zona would know?

[Scott Zona]

The "reins" and that brittle bit at the tip of the spear are all part of the same tissue, the "leftover" tissue after the leaf develops plications. In the leaf development of palms, the leaf begins as an entire leaf. Later in its development, the plications form, and then finally the leaflets separate. The marginal tissue of the leaf is leftover and falls off as the reins.  This brittle bit is also "leftover" tissue, the tissue that didn't get plicated and divided. I have to admit, I've never seen an example this long (but then, I've never grown Archontophoenix). Thanks for posting the video and photos. Really fun to see. 

[96720]

I have noticed this and they seem to last way too long keeping the frond from opening I usually help the frond open I figured it was partially due to our dry climate interesting that it also happens in more humid places!!!

[Xerarch]

Looks like what I get on foxtail, but not always at the tip, this one is attached pretty far down the frond, but same thing, very brittle. 

[flplantguy]

I noticed that on a lot of mine and figured it was to help the new spear emerge properly without ending up deformed or something similar. One of the flamethrowers today looked like a perfect example of it.  I'll see if I can gets good photo of it.