You could always try typing it out from the description. There's not enough detail of the stipules in the photos. Note it is mentioned that the flowers rarely open in cultivation.
5. Drosera dielsiana
5. Drosera dielsiana Exell & Laundon in Bol. Soc. Brot. 30 : 214 (1956). Type : Transvaal, Lydenburg district, near Spitskop, Wilms 35 (BM, holo.).
Small, hairy herbs with compact, basal rosettes and a few fairly long thin roots. Leaves 15-25, the old leaves soon disintegrating, apetiolate; stipules small, fimbriate, auriculate; lamina spathulate, up to 2 cm. long, 6 mm. broad above, apex rounded, tapered below into a broad, hairy petiolar part; both types of tentacles present; lower surface sparsely hairy. Inflorescence with the scape leafless, sturdy, straight or rarely somewhat curved below, 10-20 cm. long, hairy near the base; usually about 8-flowered (3-12) with the rhachis erect; flowers secund, small, seldom open according to collectors; pedicels 2 mm. Calyx-lobes c. 5 mm. long. Petals obovate, unguiculate, c. 7 mm. long, pink, mauve, violet or white. Stamens with narrowly winged filaments. Styles forked from the base with the stigmatic apex spoon-shaped, membranous. Capsule oblong, 5 mm.; seeds ovoid, 0.4 mm. black, honeycombed. Fig. 28:5
Found on the escarpment in the eastern Transvaal, in Swaziland and northern Natal and further northwards in southern tropical Africa, apparently on mountain plateaux. Flowering during the summer months.
NATAL.-Utrecht : Naauwhoek near Utrecht, Devenish 978.
SWAZILAND.-Mbabane : Nduma, Compton 25381
TRANSVAAL.-Barberton : Godwan River, Berlin, Hofmeyer sub PRE 15280. Letaba : The Downs, Junod 4427. Lydenberg : Steenkampsberg, 15 kilometres E. of Draaikraal, Strey 3031; Mount Anderson, Strey 3536; Galpin 13738; Prosser 1796. Pilgrim's Rest : Mariepskop, Van der Schijf 4544; Meeuse 9954.
Since the flowers seldom open, it is possibly an apmoict.
Grand Hotel... always the same. People come, people go. Nothing ever happens.
I knew that was online somewhere. kept on forgetting. Will be trying to do the microscopic photos of the seeds next week.
I think you are an "expert" on these South African taxa and have learned much from you! Besides, you've been there!
I've written to Robert regarding this strange and confusing plant and am awaiting reply.
NAN, part of the problem with diagnosis is that when using the published Keys all of the criteria must be examined and taken into account. Often, there are some criteria present that support a diagnosis, but rarely are all the criteria present in any given example, and my teachers have stressed there is no better or stronger indicator, all criteria have equal value. When studying herbarium sheets or doing field work, the difficulty is not so great because there are numerous examples from which to compare, but for "orphaned" plants in collections there is usually just the example presented and "pure" species meeting all the conditions for diagnosis simply don't exist in individuals. Even the "type" specimens are subject to this variability. Taxonomy is a highly opinionated science, and opinions are only good as familiarity allows. Christian has grown and studied these taxa more deeply than I have I believe so I respect his opinions more than my own impressions.
I agree, there isn't much sense in discussing origins except for the mental exercise (or head banging if you prefer). The best solution for future generations is to publish it at cultivar rank, providing some history and a central reference for horticultural growers interest vs taxonomists. I would be pleased to do so if I ever have a chance to grow and assess it. It needs doing!
Hopefully, Dr. Gibson will shed some light on the mystery, I respect his opinion most of all!
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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!
thanks! That's not ovoid to me! So, i still think i am right and almost noone is cultivating true Drosera dielsiana.
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........
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 ----------
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.
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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?