They look like twins!
X
Datura/Brug Bud Comparison .. No Wonder People Are Confused
I really like your photo comparison.
Thank you.
X
I am maybe old fashioned and out of date, but I still consider them to be one genus. If you think about it, Datura and Brugmansia has been considered one and sometimes two genus several times throught a few centuries. Right now consensus is that they are distinct, but what are consensus, but persons opinions blowing hither and dither by the wind of time. In for instance Peoneas there are both herbaceous and woody species and in apples, pears and grapes, there are species and lines which are not pollen compatible (but that doesn' t make the less apples etc.), along with lines which are self incompatible and lines which can pollinate itself.
Tonny are there any with intermediate seed structure?
I will try hard not to make this a long novel.
It is hard to say, Alistair. It has been a long time, since I had seeds under the microscope. There are visual similarities of the surfaces of the seed coats of B. sanguinea and D. ceratocaula. I don' t know, what the materials, it is composed of, is called, but compared to all other Datura and Brugmansia seeds, both of these have a much better abillity to withstand the penetration of water. They will sink to the bottom, if you put them in a glass of water eventually, but it take longer time. I can see why it is so with D. ceratocaula as it grows in the shallow waters of lakes in Guadalajara. I am not sure, if the populations along the lakes of Mexico city still exist. Of course, D. ceratocaula seeds has to withstand water for a while to be dispersed to other areas, but I don' t right get it, why B. sanguinea has inbuild the same mechanism? I hope that you have a few suggestions to help me out here?
Doesn' t you sometimes wonder, why the position of the flowers was used as one of the distinguising marks Between Datura and Brugmansia? ... or the fruits?
I do wonder if certain characteristics of D. ceratocaulis (which has sometmes been cited as an internediate in several respects between Brugmansia and Datura) aren't convergent with Brugmansia rather than evidence of them being deservedly regarded as one genus.
What really matters in this question is whether any species of Datura are more closely related to species of Brugmansia than they are to other Daturas (and vice versa).
If they are not, then the question of whether or not they are separate genera in the tribe Datureae, or different subgenera in Datura is largely cosmetic. In that case I think it should not be changed as we are now fairly used to calling them by separate names.
The flower position character (IMO) is not important in defining the genera , just useful to help people recognise/identify them (of course it doesn't work all the time anyway as there are some cvs of Brugmansia with upright or semi-upright flowers).
Has there been tested whether Datura can be cross polinated by brugmansia? I was just currious. In my climate, my brugs are killed back to the ground thus there would be no time to make seedpods. But, I can try to grow one under greenhouse and perform an experiment. What's your thought?
Tonny knows more about this than I do, but for normal practical purposes Datura and Brugmansia cannot be crossed.
There is some literature from the late 1940's (I think) where a Datura/Brugmansia hybrid was raised under laboratory conditions but I believe it died out.
I used to grow Datura, but since my beloved Brugmansia came into my life, I've dumped all of my Dats.
All I can say is, that Dats are normally annuals and I have to save seeds. Dat flowers point upward and don't last long. Brug flowers point downwards and last much longer. I can easily save cuttings.
There is no comparison, as far as I'm concerned. Brugmansia wins.
Can I take cuttings of daturas like a brug?
Being an annual, I've never heard of taking Dat cuttings.
Someone may prove me wrong, but I'm doubtful.
Datura and Brugmansia do not cross naturally and my attempts of crossing them in less natural ways always ended up as failures. It might have to do with the pollen and the pollen tube on the other species do not have the size to fit into one another. But don' t let that discourage you. Keep on crossing them, you never know, if and when you hit two parent plants with the right combination.
You can take cuttings of Datura. I have not had the best of luck myself, but a hybrid such as the variegated Datura wrightii 'Missouri Marble' is propagated by cuttings.
Alistair,
Yes, I read that thesis, that D. ceratocaula should be considered an intermediate species, but besides from the similarity to B. sanguinea in its seed coats and the fact that the fruits is spineless and consist of soft, green and white tissue, the similarities begin to cease rapidly. When I come to think of it, I have never found much woody fibrous tissue in D. ceratocaula, only a bit in at the base of the plants, whereas woody tissue are present in all older parts of any other Datura species. A species such as D. stramonium can be woodlike up above the Y in older plants. The three perennial Datura species are naturally also woody in the lower areas. It is funny, btw. that while D. ceratocaula nearly lack woody fibers, D. stramonium and many other has woody fibers mixed with firm herbaceous fibers, but in the three perennial species, the all of herbaceous fibers are soon growing into hardened, woodlike fibers.
That was a little beside the subject, I know, but I am not sure that there are an intermediate species. Why that is, I don' t know. You could be right in that they are two different genera. No one knows for sure, how many years the Datura and Brugmansia ancestors has been growing on earth. Now, this is pure speculation, but if they originally came from the same ancestors and these was strictly separated byt f. inst. earthquakes, iceages or in some other way ended up in each their insulated areas and have evolved further in each their different environment, then could it not be possible, that it explain the lack of the intermediate sp.? If the speculation holds I would prefer to think, that the ancestor species had a lot of intermediate seedlings, but that natural selection killed those not fit to survive in the environment? I mean, that when a Datura or Brugmansia wild species no longer have intermediate seedlings in ou days, that the reason is, that those plants which bore those particular genes was becoming extinct 100.000's years ago?
I always believed the dat was an annual also. But I planted seeds last year that my daughter-in-law gave me and they did great. Then died out in the winter and came back and are blooming beautifully -- behaved much like brugs. Must be the climate here in Florida. Since the original seeds had been a gift, I thought maybe I could carry it forward, so to speak.
As a lay person, and novice in Dats. I can confirm that Dats. cuttings can be done successfully. I've done it. :-)
Tonny in broad terms yes I imagine something like that happened. The taxonomic question can however be posed in (largely) present day terms: are either (or both) of Datura and Brugmansia heterogeneous i.e. containing species which are actually more closely related to another genus (be it Brugmansia, Datura or something else). I think there is broad agreement that they are not heterogeneous. Then matters become reduced to the question of the rank at which the groups should be recognised. Since genera don't "exist" except as concepts, it may come down to what is more useful, less annoying etc : Datura and Brugmansia or Datura subgenus Datura and Datura subgenus Brugmansia!!! I vote for the former :-)