Drosera leaf vernation types

[Andreas Fleischmann]

Hello,

As this discussion of distinct leaf vernation types (i.e. the way that young leaves enfold from bud) that Fernando and I started in the CP photo part of this forum led too much from the original post, I decided to continue discussing here. Actually I would have started a private discussion with Fernando by e-mail or phone maybe, but as we started in this forum, some users might be interested to follow it? If not, we can easily delete this topic ;).

So the main question that came up (because Vince showed photos of a D. capensis that had circinate laminas in bud, not involute ones as usual for this species) is: does the way in which the Drosera plants enfold their leaves reflect systematic relationships?

Circinate vernation = leaves rolled inwards in bud, like prominently shown in Drosophyllum, for example.

Involute vernation = leaves folded in bud, margins of the leaf folded inwards, like the trap of Dionaea in bud, for example, or developing leaves of D. capensis

So I will resume with Fernando's last post here:

I agree that leaf vernation has more to do with leaf shape, but I guess this means that leaf shape is heavily influenced by phylogeny in Drosera, don't you agree?! :)

partially, yes, but with common exceptions! ;)

>You are right, the two South African groups of paraphyletic section Drosera and the included section Ptycnostigma generally show two distinct ways to enfold their leaves (involute in Drosera vs circinate in Ptycnostigma). But for example D. hilaris shows some transition, having involute short leaves after dormany in early growth, and circinate leaves (although the character is just pronounced weakly) in full growth.

Interesting! It could be an intermediate between both groups, don't you think?

That's what I already suggested because of various other characters, too: highly reduced stipules (lacking fully in Ptycnostigma); tendency for pronounced dormancy, even if kept wet; stigma shape (tending towards the type of Ptycnostigma); and, maybe not as essential, even flower size.

>In D. alba, the rosette leaves are more or less involute, whereas the upright filiform leaves are fully circinate.

Hmm, I couldn't find any pics of your D.alba rosette leaves to see this, do you have any?

Will post them later here.

>Circinate leaves are much more rare among Drosera, and can be found at least in those species (from memory)

>D. regia: circinate, but with involute margins

D.adelae is like this too, right?

Yes, you are right, same for D. schizandra, too. However, D. prolifera has involute leaves.

>D. villosa-ascendens-complex

>D. graminifolia

>D. chrysolepis

>D. camporupestris

>D. montana-tomentosa-complex

And D.schwackei, D.grantsaui, D.tentaculata, and a few other undescribed species from Brazil... ;)

Sorry, I did still count D. schwackei as member of the montana-complex, which it is clearly not ;)

I will have to disagree with D. grantsaui, which has involute leaves (see photo, inserted later), like it's sister D. communis.

Edit here: I just looked at my plant of D. grantsaui, and noticed the following: juvenile plants and short leaves are involute in bud, whereas the larger leaves of fully mature plants are circinate! Thus in this species, it seems to switch!

The hirtella-complex, D. brevifolia-complex and the Venezuelan Drosera have involute leaves. I cannot say for sure for D. cendeensis, which would be interesting because of the shape of leaves, but I think from memory that it's involute. I'm not sure for D. tentaculata, but can certainly say that D. spec. 'Shibata's' has circinate leaves.

>D. caduca, non-carnivorous leaves (which are just a petiole) just had a look at it, interesting: the petiole is involute itself, but the tip is circinate

Do you have any pics of this???

As son as I'm back home from university, I'll insert the photos here. ;)

>D. filiformis of course

But curiously not D.linearis nor D.anglica, correct?

You are right, they have involute leaves. Thus once again a mismatch with phylogeny.

All the best,

Andreas

Edited April 2, 2009 by Andreas Fleischmann

[Fernando Rivadavia]

Hello Andreas,

Interesting to think that Vince's plant could be a hybrid with a S.American species... that would be fantastic!!

partially, yes, but with common exceptions! ;)

This is what I want to find out: are the exceptions common or is there an underlying rule possibly showing relationships...

That's what I already suggested because of various other characters, too: highly reduced stipules (lacking fully in Ptycnostigma); tendency for pronounced dormancy, even if kept wet; stigma shape (tending towards the type of Ptycnostigma); and, maybe not as essential, even flower size.

See?? Even the exceptions may pinpoint some interesting data regarding Drosera relationships... I thought it was strange in my phylogeny how D.hilaris showed up close to D.alba -- but maybe not that strange anymore.

I will have to disagree with D. grantsaui, which has involute leaves (see photo, inserted later), like it's sister D. communis.

Edit here: I just looked at my plant of D. grantsaui, and noticed the following: juvenile plants and short leaves are involute in bud, whereas the larger leaves of fully mature plants are circinate! Thus in this species, it seems to switch!

Good thing you edited before I could finish my post, hehehe! I was looking through my pics and it seems that the leaves are circinate -- but they're all mature plants. See pics below:

(Last picture taken by Ed Read)

This brings up a very interesting subject: I've always been curious about the phylogenetic position of D.grantsaui. You said it's sister to D.communis, but do you have any molecular data to support this? The fact that it has 2n=40 and crosses with D.tomentosa tells me it may convergently be similar to D.communis but may actually be closer to D.tomentosa.

The hirtella-complex, D. brevifolia-complex and the Venezuelan Drosera have involute leaves.

And they're apparently all on the same phylogenetic branch of mostly New World and mostly diploid taxa...

I cannot say for sure for D. cendeensis, which would be interesting because of the shape of leaves, but I think from memory that it's involute.

I'm not sure either, in the crappy pictures I got from Dunno they look circinate. It would be interesting to find out about D.peruensis too. In fact, what about D.arenicola and D.neocaledonica?? They look involute in the few pictures I've got...

I'm not sure for D. tentaculata, but can certainly say that D. spec. 'Shibata's' has circinate leaves.

Yep, both circinate!

You are right, they have involute leaves. Thus once again a mismatch with phylogeny.

Nope it's a MATCH! All the species which seem to fall into my phylogenetic branch of mostly New World and mostly diploid taxa have involute leaves (except for D.filiformis), see pic below:

Best wishes,

Fernando Rivadavia

[Dave Evans]

I don't know what to make of this... I'm not seeing anything but Involute vernation in Drosera.

 

The leaves unfurl outward in all directions, some are just more spiraled because the lamina are super long.

[Fernando Rivadavia]

Dave, compare similar shaped leaves like D.aliciae and D.tomentosa. Notice how the first has the lamina folded over the petiole, while in the latter the leaf is all rolled up. Then compare plants like D.capensis and D.villosa and you will see the same thing (with the exception of that one D.capensis form that caught our attention *because* it was the exception). Although in some cases vernation seems to correlate to leaf shape, in most it seems to follow a phylogenetic pattern.

 

 

Best wishes,

Fernando

[Zlatokrt]

Interesting discussion. Thank you Andreas for pointing it separately, i would probably miss it in the general forum :-)

I can see some pattern too, however i am quite curious about a few things. Is there any anatomical difference between leaves with circinate/involute vernation? It does not sound like it is only a function of a leaf shape, it appears across different leaves, but still, what causes the leaf to vernate in a certain way? And what makes me also curious is the fact, that circinate vernation is quite ancient trait, found mostly in ferns and cycads. Is the circinate vernation in Drosera the same, caused by some ressurected ancient genes or something like this, or is it a newly evolved trait, just a convergency? I would guess the latter option...

 

I found an article (Grubb & Jackson 2007; link), where the authors hypothesize the importance of rolling and folding of leaves as a protection against invertebrate herbivores (they did not include Droseraceae, but i find their hypothesis quite interesting). Some type of vernation is found in all Drosera species, however it could explain how this trait is useful to them and its ancestral origin - the leaves of CPs in general are quite expensive organs, photosynthetically unefficient, and most CPs do not produce many leaves, at least compared to other plants. Protecting them during the developement would definitelly be a good idea :-)

 

Regards

Adam

Edited July 31, 2014 by Zlatokrt