User Tag List

Informational! Informational!:  0
Likes Likes:  0
Page 4 of 5 FirstFirst 12345 LastLast
Results 25 to 32 of 38

Thread: What Exactly is D. sp. South Africa?

  1. #25

    Join Date
    Dec 2002
    Location
    Germany
    Posts
    361
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hi,

    this is looks like the plants again, that i do not think are D. dielsiana at all! Btw, the description above from Obermeyer is not the type description! But it is good enough to show you, that the plant above does not fit

    "Inflorescence with the scape leafless, sturdy, straight or rarely somewhat curved below"
    I can easily see a very much curved scape!

    "Styles forked from the base with the stigmatic apex spoon-shaped"
    The stigmatic are divided not only at the base, but also towards the apex. So, this should also not fit!

    I am really looking forward to the seed pictures! I would not be surprised if they would not fit: "seeds ovoid, 0.4 mm. black,"

    So far my understanding, others might have different opionos Btw, i really like discussing these plants!! Thanks for asking Dr. Gibson, William! I am really intersted in his opinion!

    regards,
    Christian

  2. #26
    kulamauiman's Avatar
    Join Date
    Jul 2009
    Location
    Kula, Maui USA
    Posts
    1,921
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)


  3. #27

    Join Date
    Dec 2002
    Location
    Germany
    Posts
    361
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hi,

    thanks! That's not ovoid to me! So, i still think i am right and almost noone is cultivating true Drosera dielsiana.

    Christian

  4. #28
    kulamauiman's Avatar
    Join Date
    Jul 2009
    Location
    Kula, Maui USA
    Posts
    1,921
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    without magnification they looked superficially round. Even at 10X hand lens inspection. Seems my eyes are going bad faster than I though. Put them under a scope and details start emerging.

    Have had one idea that is bugging me. can see cultivation conditions affecting things like color and leaf size and or shape in some cases. It probably wound never affect seed morphology (perhaps size at the most) so couldn't the shape and external morphology of the seeds be used almost like fingerprints? Admittedly might need to do SEM work to see the ridges and intricate details as I was pushing my scope and doubt I have the quality to do that much detail........
    MTF

  5. #29

    Join Date
    Dec 2001
    Location
    Oswego, New York, U.S.A.
    Posts
    5,290
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I have Dr. Gibson's response regarding Drosera dielsiana. As I anticipated, he referred me back to the publication by Excel and Launders and shares my opinion that the "best" criteria is the seed form and texture taken into account with the division of the styles.

    "You have raised an interesting question about Drosera dielsiana/ D. natalensis. Drosera natalensis is a highly variable taxon and I am not sure if I have seen its typical form (but have finally received seed of the apparently 'true' D. natalensis that I look forward to flowering over the coming summer). What I thought may have been D. natalensis in the field, on the South African south coast between George and Tsitsikama now appears to be D. aliciae - all of my samples were sent to Germany and I have so far not had a chance to study any material in more detail. I am reasonably confident that I saw D. dielsiana in the wild between Knysna and Durban, based primarily on leaf shape. However, as shown in the Exell and Laundon paper in which Drosera dielsiana was described the key difference between D. dielsiana and D. natalensis is seed size (and also style division) and between D. natalensis and D. aliciae is the nebulous character of leaf 'toughness'. The problem is also compounded by natural and artificial hybrids between D. natalensis, D. venusta (if indeed this is distinct from D. natalensis), D. dielsiana and D. nidiformis."

    I include this quote for the range data it contains, in hopes it may prove useful on your next visit to South Africa:

    "The chromosome counts would not suggest it is a recent hybrid, but other genetic work may shed some useful insights into its origins. Its current distribution is sporadic; along mountain
    tops from Natal to Zimbabwe".




    Unfortunately, neither of these characteristics are 100 percent dependable. Seeds from cultivated plants are typically longer, and there is always the question of random hybridization. Simple variability ( even in the field populations) means that taxonomy must be a best guess, taking into account all the criteria. As Robert cautions:

    "Seed and flower structure would help, but beware the absolutes in publication for these plants do not read them and merrily disregard them, e.g. Excel and Laundon's paper. As to to what the "true" species looks like this has been set by the designation of the type species. Hopefully what was collected and designated such was typical of what was there - but there are no guarantees. Also, many early collections have been made in the absence of a good knowledge of full variation within the species (e.g. within the D. peltata complex), and in the intervening time many populations have been wiped out. Thus it is all good arm-waving stuff, and an article on it would surely generate some interest, and show how much subjectivity there is in taxonomy."

    This brings me back to my assertion that purity in tfrica is optimistic in the extreme for this genus even for field researchers with long experience with these populations and likely totally impossible for horticulturalists dealing with orphaned plants.

    I believe that if the seed is small and ovoid, and if the styles are MOSTLY of simple bifurcation, a reasonable determination could be for Drosera dielsiana.

    ---------- Post added at 05:00 AM ---------- Previous post was at 04:48 AM ----------

    Aloha kulamauiman!

    As mentioned above seeds are indeed affected by etiolation in cultivation, and even seasonally (winter vs summer) when taken from habitat.
    There are no absolutes.
    "Grow More, Share More"

  6. #30

    Join Date
    Dec 2002
    Location
    Germany
    Posts
    361
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hi,

    thanks for the post, William!

    i don't doubt that seed shape and division of the styles are most likely the best way to differentiate between Drosera natalensis and Drosera dielsiana! Having said this, the flowers and the seeds in all plants i have so far seen identified as D. dielsiana do not look at all like what i would imagine from that species. I also can in no way imagine, that the seeds of the above shown plants would be ovoid if this plant grew in habitat. The seeds of the picture are clearly fusiform (according to my understanding). These caracters both put the plants to D. natalensis for me.

    William, did you show Dr. Gibson the pictures of the plants here? I would really like to know what he says to these plants. Could you get me in contact with him, Tamlin?

    regards,
    Christian

  7. #31

    Join Date
    Dec 2001
    Location
    Oswego, New York, U.S.A.
    Posts
    5,290
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hi Christian,

    Robert did not comment on the question of D. ?. although I do believe he is aware of this plant. I will write to him with an introduction to you, and will inquire if he wishes the correspondence. He is a very kind (but busy) gentleman and if he is willing I will send you his email addy.

    You are correct, the seeds are fusiform and do not support the determination for Drosera dielsiana based on this criteria.

    I have an off topic question for you. Have you ever seen any Drosera natalensis from Madagascar?
    Dr. Schlauer told me once in a correspondence that this locale is likely to have the most "pure" D. natalensis, but I have never seen these plants and would very much like to!
    "Grow More, Share More"

  8. #32

    Join Date
    Dec 2002
    Location
    Germany
    Posts
    361
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hi,

    thanks!

    So far i have not yet grown or seen D. natalensis from Madagascar. The type of D. madagascar is from the Area around Durban, so i really wonder why the plants in Madagascar should be the most pure ones. I will have to ask some of our german experts about this plants in the near future. This topic has really increased even more my interest in these species!!

    Christian

Page 4 of 5 FirstFirst 12345 LastLast

Similar Threads

  1. Anyone in Southern Africa?
    By nimbus in forum Foreign Carnivorous Plant Resources
    Replies: 1
    Last Post: 11-18-2008, 08:03 AM
  2. CPs of South africa & Last of the Head Hunters
    By swords in forum General Discussions
    Replies: 4
    Last Post: 10-26-2003, 08:57 AM
  3. Africa?
    By in forum Foreign Carnivorous Plant Resources
    Replies: 0
    Last Post: 02-02-2003, 10:45 PM
  4. Drosera in East Africa ?
    By Martin in forum Sundews (Drosera), Byblis, Drosophyllum
    Replies: 2
    Last Post: 08-08-2002, 12:13 PM
  5. Anyone in/going to Africa / South America?
    By in forum General Discussions
    Replies: 1
    Last Post: 05-25-2002, 06:30 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •