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  • #61
Hi Christian,

Those are beautiful flowers, but I question the identity of D. dielsiana based on the repeatedly divided styles which are more typical of plants in the Drosera aliciae/natalensis complex.  Although repeatedly divided styles (not simply bifurcated from the base) are occasionally found in D. dielsiana, they are rare.

Here is a photo I consider to be more typical regarding the bifurcation of the styles.

The smaller rosetted plants in your photo are likely to prove closer to D. dielsiana. As I mentioned earlier, D. natalensis and D. dielsiana are closely allied taxa. D. dielsiana was separated from D. natalensis by Exel and Laundon on the basis of seed shape and length. The seeds of D. dielsiana were described as “ovoid, 0.3-0.4x0.2 mm” vs. those of D. natalensis described as “ellipsoid-fusiform, 0.5-0.6 mm long …0.2 mm broad." I assume this rather precise measurement was used to divide the two taxa in the area where their range overlaps, and introgression produces too many phenotypes for floral criteria to be effective.

Drosera dielsiana has been successfully hybridized with D. nidiformis and D. natalensis, and since the F2 generation is likewise fertile, the possibility of different forms is endless.
("sp. Durban" and " sp. 4 South Africa" are likely to be 2 of them)

Drosera_dielsiana_flower_5!.jpg
 
  • #62
I have been cautioned by my mentors not to place any ultimate reliance on the various taxonomic keys for the process of species determination.  Field work and herbarium study is essential to understanding the nature of these populations.

For most of us, the literature is all we have to go by, and it is solely from my own experience with my plants, and from the various published keys that my comments are drawn, along with some very helpful education from Dr. Jan Schlauer, Robert Gibson and Vitor Olivera de Miranda that I base my comments on.

In reply to my question of "Just how reliable is the information found in the various published keys?" Robert Gibson had this to say in reply:

"Botanical knowledge is iterative, so even the best keys and
descriptions are dependent upon the nature and extent of the collections behind them and the authors knowledge of the living plants. So most keys and descriptions come unstuck somewhere along the way. Also, treatments
like Obermeyers were based on specimens in only part of the range, so may give a false impression where other variants exist further afield.

What is "typical" technically comes down to the type collection(s), which has inherent dangers if the collections are old or poor, not to mention that they may prove to be atypical to the rest of the population that is given the name from that type! Then there are also seasonality factors that can cloud the issue further, e.g. small compact rosette in
the dry season and large, luxuriant rosette in the wet season." (Robert Gibson Pers. Comm. 031603)


I like this comment as well, made by Dr. Jan Schlauer:

"The reason for the seemingly non-scientific (or non-exact) nature of taxonomy is that there are no nearly as finite, constant, and well-defined items in vivo as in litteris. Taxa are theoretical concepts constructed by the human mind, not the things that really exist and happen in nature. You may regard this insufficient and error-prone (and you are right&#33
wink.gif
, but I think (and I know many colleagues agree here) it
is the only way to think and to communicate about these natural beings and processes among humans. Our mind is not prepared for more complex analysis and comprehension. This is why names and their proper use are so important for most of us..... Mankind has tried to find a precise, general,
and reliable species definition for many generations without appreciable success. The crux is "species" do not really exist out there. Living beings are not constant."
 
  • #63
Hi Tamlin,

On our german board we also had a discussion about some of these sundews. The photo from above (the plants, not the flowers) was shown by another member, and I was told to have a form of Drosera dielsiana that is near to Drosera venusta.

I'm very interested in pictures, that show the flower details of these species. If someone has a good picture, it would be great if you could email them to me, or post them here.


Christian
 
  • #64
Hi Tamlin,

As per request here are some close-ups of the plant, a little sharper this time. The stipules are quite evident.

glabripes.JPG


and some close-ups.

closeupofglabripes.JPG
closeup2.JPG


I think the there are enough stipules present to point to a positive identification as Drosera glabripes. What do you think? From what I can see in the close-ups (my bare eyes can't on the plant) the stipules seem to branch, as you described.

-noah
 
  • #65
Noah,

Now I can see the stipules! This is D. glabripes in my opinion.
 
  • #66
Hi All,

Here are two pictures of my Drosera burkeana. The plant is still very small. I got them about 2 month ago. What do you think ? Could this be Drosera burkeana ?





Christian
 
  • #67
My initial impression is yes, this could be D. burkeana, or if you are lucky, D. pilosa - provided that the material originated in South Africa.

The pitted seed coat would be your best determinator. Should this plant prosper enough to produce seed, I would be very interested in seeing some of it.
 
  • #68
Hello,

My Drosera collinsiae flowers at the moment. Today one of my plants produce a flower with 6 petals and 3 styles. Here is the picture of the flower, as well as a picture of some of my plants.






Christian
 
  • #69
It's me Christian got the D. burkeana from.
My plants flowered recently - sorry, I don't have a digi cam, so I couldn't take photos. But I have seeds!
I'm happy to send a good number to you, Tamlin.
If you're interested, please e-mail me privately.

@Christian:
Do you still want seeds--in addition to the plant?

Best wishes,
Marcus
 
  • #70
Here are a couple of photos of the plants I'm growing as D. dielsiana, all comments welcome, are they correctly IDed? I grew them  from seed from the UK CPS Seed Bank.

1. Rosettes

Dielsiana1.jpg



2. Flower, they are a bit darker in reality.

Dielsiana2.jpg


Cheers

Vic
 
  • #71
Hi Vic,

Your plants look similar to the plant in the right corner of the photo i posted above [I don't believe it's Drosera dielsiana anymore (too big, repeatedly divided styles, form of the leaves)]. The flowers of your plant look differnet to the of mine. Take a look at the pictures, i posted above. Can you say anything about the size of your plants, or the height of the flower stalks ? I would be interested in this.

Here is a photo of a plant i have as Drosera dielsiana. I believe it's correctly identified. They look quite different to yours. The diameter is 3.5cm and the flower stalks reach up to 25cm.

<a href="http://www.utricularia.net/Bilder/d-dielsiana2.jpg" target="_blank">
d-dielsianatn2.jpg

</a>

best wishes
Christian
 
  • #72
Hi Christian

I'm not sure that they are D. dielsiana either, I'm also aware of the taxonomic nightmare that most S. African rosetted sundews present.

The largest rosette in my colony has a diameter of 3.5 cm and the tallest flower stalk is 25cm, which is an amazing coincidence!!, but true, I've just measured them without reference to your dimensions.

Maybe the flower picture isn't too clear, just my luck to catch them flowering on a cloudy day. The styles on my plants are not repeatedly divided however. They are only divided once = bifurcate, though this is more obvious, or deeply so, on my flowers than on the picture Tamlin posted above.

Cheers

Vic
 
  • #73
Vic, can you give us an idea of the scale of your image?

In appearance it seems more like Drosera natalensis or even Drosera venusta than Drosera dielsiana.

Tamlin we could use your expert eye.
 
  • #74
The largest rosette in the photo (bottom right-hand corner) has a has a diameter of 3.5cm. The plants are all, mature, flowering plants, two years-old.

Vic
 
  • #75
This appears to me to be a variant of D. dielsiana. I trust you all have read what I have said concerning specation in the South African plants. There are no easy answers. The simple bifurcation of the styles does not support D. natalensis or D. aliciae as a determination. The petiole is not tetrete, so it cannot be D. burkeana. Since the plant is flowering, I doubt it is a juvenille form of D. nidiformis, although there is a good chance that this may be a hybrid of D. dielsiana and D. nidiformis which are closely allied species. Sorry I cant help more. If I ever get back online to get to my email, I will ask Robert Gibson's opinion, and will post his reply as soon as I have it.
 
  • #76
Hi,

Here is a photo of my Drosera natalensis. It should be a correctly identified plant.





Christian
 
  • #77
Hi William,

I read your post on the CP listserve. You described exactly my situtation. I do have many Drosera, which i'm not sure about the identity and they all look somehow different. All i can say is, they look like, or it could be a
confused.gif
, as you wrote in your post. I will not come to a definite determination, cause i have too less experience in identifieng them. I'm of the opinion, that in some cases a definite dermination is nearly impossible. The species seem to be very variant. So, it's quite hard, if not nearly impossible, to find a plant, that matches exactly the published descriptions, like Obermeyer's Key or Robert Gibson Article. I really woud like to know, which plants i do have in my collection. Maybe there are some surprises, i never thought of.

I know many people, who have the same problem. And much mor will most probably not even know, they have wrong labeled plants. These facts are very disappointing.

best wishes

Christian
 
  • #78
I am still waiting for an informed answer to my questions, but it is likely not to happen on the listserve.  I am going to try to get Robert to join the group (at least long enough to give his opinion, he is VERY busy) and hopefully shed some light on the problems regarding identification of South African species.  Hang in there Christian, but be prepared to accept the possibility that we will NEVER be able to assign a species determination to an isolated example of a South African population.  This is my current opinion, and I am waiting for a reply that changes my mind on this issue.  So far, there have been no convincing replies.
 
  • #79
Tamlin

Good luck in your efforts with regard to trying to unravel the complex taxonomy of the rosetted S. African Drosera. It would be excellent if the likes of Robert Gibson could be persuaded to shed some light.

Below are a couple of pictures I took yesterday of a plant labelled as D. admirabilis growing in the collection of a well known UK grower, **** Jones. The rosettes on these plants were tiny, less than 1cm on the largest and smaller than that on several in flower, which was about 1cm diameter. Any comments/discussion on this one welcome, I have seen other plants labelled as this species, but these look like the real McCoy to me.

admirabilis1.jpg




admirabilis2.jpg


Cheers

Vic
 
  • #80
Vic,

As I understand it, D. admiribilis was rejected as a synonym for D. cuneifolia...I need to research this. I have no experience with with either form, and am working on acquiring D. cuneifolia to become better acquainted with it. There's not much I can offer on this one I'm afraid, other than to note an absence of the constricted cells along the lamina which gives both D. cuneifolia and D. slackii a sort of bulge.

I can say that it looks like nothing I have seen but this looks very much like a plant I was recently sent photos of which I likewise did not recognize, Patrice, if you read this take note! Its a real beauty though, and the flower is unique to me!

Robert is a very busy man, but let's hope for the best. I have yet to plead my case with him, but I will soon! Let's all hope that his book comes out: he's writing one on South African CP, which he told me should be out around 2005. Personally, I am drooling!
 
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