Lemna and other duckweeds

From: "Eduardo Goncalves" edggon at hotmail.com> on 2000.06.21 at 01:45:33(4863) Dear Aroiders, Since I received some private messages concerning my last not-so-funny joke, I think I should present this aspect to the whole list. Some say they are shooked-up about the fact that Amorphophallus and Lemna being close relatives. Others corrected me, saying that Lemna is a genus of Lemnaceae (duckweed family), not an aroid. Ok, I have a bombastic new to the members that have been sleeping for the last five years. Yes, all duckweeds are true aroids! In fact, duckweeds can be better considered like an aroid than Gymnostachys, Orontium and Symplocarpus! I will try to explain it (before you try to beat me)... Taxonomy has suffered an irreversible micro-revolution in recent years. Since Linnean times, taxonomy deals exclusively with morphological aspects like shape of organs, color, etc. The taxonomic dataset has been improved by plant anatomy (or micro-morphology), chromosomic features and phytochemistry, but all of this aspects concern phenotypic information. After the discovery of the structure of the DNA by Watson & Crick, we became able to take a closer look to the essence of the living beings, i.e. we can 'read' their genes. It is true that it is not so simple to access and compare genes, but it is potencially a very powerful tool. Lemnaceae has been considered a "good" family for much time, since they are all free floating plants, with similar reduced flowers. Until very recently, most taxonomic treatments include Lemnaceae as a distinct family, always based on phenotypic features. If I am not confused, in the book "Families of Monocotyledons", R. Dahlgren and colleagues included Lemnaceae in the order Arales, together with Araceae. In French's work (with collaborators) concerning the cladistic analysis of restriction site changes in Araceae, the genus Lemna was included. Interestly, it appeared well nested within the "advanced" aroid genera, being closer to a "twig" that includes Amorphophallus, all Caladieae, all Areae and all Colocasieae. Just for information, the "twig" with Gymnostachys, Orontium and Symplocarpus ("Proto-Aroids") are very far from it, and seems to be almost as a syster family. The same you can see if you analyse the sequence of the genetic marker rbcL. These data with rbcL were not published, but I used the sequences I imported from GenBank, just for fun. I surveyed Lemna and Spirodela (both from the Lemnaceae) and both appeared like "advanced" aroids. Once again, the Proto-Aroids appeared so related to the other aroids as a Potamogeton I used in this analysis! This is to show you that if you put Lemnaceae as a distinct family, you should also separate Gymnostachys, Orontium and Symplocarpus in a distinct family, and probably a miriad of other "small families". I don't think it would be a good idea, since I love aroids with all currently recognized genera! I know that Lemna and all the other genera in Lemnaceae don't look exactly like an aroid. They are a very specialized group of free-floating plants, with very fast vegetative reproduction. The reduction in their reproductive organs (maybe because big flowers make small plants to sink in the water) seems to be strongly adaptative, and resulted in the poor recognition of these plants like true aroids. However, we can't say that they are not aroids only because WE couldn't recognize them before! If we want a taxonomy based on the evolutive history, I think we should consider those diminute duckweeds like true aroids, just like we recognize an outrageous A. titanum! Ok, who will be the fist one to shoot me? Best wishes, Eduardo. +More ________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com

From: "Peter Boyce" p.boyce at rbgkew.org.uk> on 2000.06.22 at 00:36:02(4876) Eduardo Hurrah! Pete +More ---------------------------- Peter Boyce Herbarium Royal Botanic Gardens, Kew Richmond, Surrey TW9 3AE Tel. (+44) (0)20 8 332 5207 fax. (+44) (0)20 8 332 5278 email: p.boyce@rbgkew.org.uk (work) boyce@pothos.demon.co.uk (home)

From: "Gabe Thomas" CDANIELLE at prodigy.net> on 2000.06.22 at 00:37:45(4877) All this time I thought I didn't have anything I could trade to fellow aroid enthusiasts and it turns out I have millions of little aroids floating around in my water gardens... Duckweed anyone? Gabe Thomas +More ----- Original Message ----- To: Multiple recipients of list AROID-L Sent: Tuesday, June 20, 2000 6:48 PM Subject: Lemna and other duckweeds > Dear Aroiders, > > Since I received some private messages concerning my last not-so-funny > joke, I think I should present this aspect to the whole list. Some say they > are shooked-up about the fact that Amorphophallus and Lemna being close > relatives. Others corrected me, saying that Lemna is a genus of Lemnaceae > (duckweed family), not an aroid. Ok, I have a bombastic new to the members > that have been sleeping for the last five years. Yes, all duckweeds are true > aroids! In fact, duckweeds can be better considered like an aroid than > Gymnostachys, Orontium and Symplocarpus! I will try to explain it (before > you try to beat me)... > Taxonomy has suffered an irreversible micro-revolution in recent > years. Since Linnean times, taxonomy deals exclusively with morphological > aspects like shape of organs, color, etc. The taxonomic dataset has been > improved by plant anatomy (or micro-morphology), chromosomic features and > phytochemistry, but all of this aspects concern phenotypic information. > After the discovery of the structure of the DNA by Watson & Crick, we became > able to take a closer look to the essence of the living beings, i.e. we can > 'read' their genes. It is true that it is not so simple to access and > compare genes, but it is potencially a very powerful tool. > Lemnaceae has been considered a "good" family for much time, since > they are all free floating plants, with similar reduced flowers. Until very > recently, most taxonomic treatments include Lemnaceae as a distinct family, > always based on phenotypic features. If I am not confused, in the book > "Families of Monocotyledons", R. Dahlgren and colleagues included Lemnaceae > in the order Arales, together with Araceae. > In French's work (with collaborators) concerning the cladistic > analysis of restriction site changes in Araceae, the genus Lemna was > included. Interestly, it appeared well nested within the "advanced" aroid > genera, being closer to a "twig" that includes Amorphophallus, all > Caladieae, all Areae and all Colocasieae. Just for information, the "twig" > with Gymnostachys, Orontium and Symplocarpus ("Proto-Aroids") are very far > from it, and seems to be almost as a syster family. The same you can see if > you analyse the sequence of the genetic marker rbcL. These data with rbcL > were not published, but I used the sequences I imported from GenBank, just > for fun. I surveyed Lemna and Spirodela (both from the Lemnaceae) and both > appeared like "advanced" aroids. Once again, the Proto-Aroids appeared so > related to the other aroids as a Potamogeton I used in this analysis! This > is to show you that if you put Lemnaceae as a distinct family, you should > also separate Gymnostachys, Orontium and Symplocarpus in a distinct family, > and probably a miriad of other "small families". I don't think it would be a > good idea, since I love aroids with all currently recognized genera! > I know that Lemna and all the other genera in Lemnaceae don't look > exactly like an aroid. They are a very specialized group of free-floating > plants, with very fast vegetative reproduction. The reduction in their > reproductive organs (maybe because big flowers make small plants to sink in > the water) seems to be strongly adaptative, and resulted in the poor > recognition of these plants like true aroids. However, we can't say that > they are not aroids only because WE couldn't recognize them before! If we > want a taxonomy based on the evolutive history, I think we should consider > those diminute duckweeds like true aroids, just like we recognize an > outrageous A. titanum! Ok, who will be the fist one to shoot me? > > Best wishes, > > Eduardo. > > ________________________________________________________________________ > Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com > > > > >

From: Lewandjim at aol.com on 2000.06.22 at 00:39:18(4878) In a message dated 06/20/2000 9:46:06 PM Eastern Daylight Time, edggon@hotmail.com writes: << Since I received some private messages concerning my last not-so-funny +More joke, I think I should present this aspect to the whole list. >> Eduardo, I think you are correct in all you have said about today's knowledge of the duckweeds. What "tomorrow" holds is another story! Jim Langhammer

From: StellrJ at aol.com on 2000.06.22 at 00:45:59(4882) In a message dated Tue, 20 Jun 2000 9:46:08 PM Eastern Daylight Time, "Eduardo Goncalves" writes: << Dear Aroiders, +More Since I received some private messages concerning my last not-so-funny joke, I think I should present this aspect to the whole list. Some say they are shooked-up about the fact that Amorphophallus and Lemna being close relatives. .and your explanation of why they are shows just how far-reaching are the effects of new discoveries. >>If I am not confused, in the book "Families of Monocotyledons", R. Dahlgren and colleagues included Lemnaceae in the order Arales, together with Araceae. Interestly, it appeared well nested within the "advanced" aroid genera, being closer to a "twig" that includes Amorphophallus, all Caladieae, all Areae and all Colocasieae. Just for information, the "twig" with Gymnostachys, Orontium and Symplocarpus ("Proto-Aroids") are very far from it, and seems to be almost as a syster family. I expect we will see more startling changes before all this is done. But, as for Arales, Lemnaceae, et al., it must be remembered that, to my knowledge at least, there is no adequate working definition of the terms "Order" and "Family," as there is (or was) for "Species." These are simply convenient categories and subcategories, which serve an important purpose: to facilitate discussion. If we threw away these terms, how could we explain what subset of the plant kingdom we were talking about? Use the taxonomic system, but do not become uptight about it.... >>I surveyed Lemna and Spirodela (both from the Lemnaceae) and both appeared like "advanced" aroids. Once again, the Proto-Aroids appeared so related to the other aroids as a Potamogeton I used in this analysis! This is to show you that if you put Lemnaceae as a distinct family, you should also separate Gymnostachys, Orontium and Symplocarpus in a distinct family. Again, expect similar revelations throughout the plant kingdom over the next few years. >>Ok, who will be the fist one to shoot me? Shoot you? Certainly not! Jason Hernandez Naturalist-at-Large

From: "Eduardo Goncalves" edggon at hotmail.com> on 2000.06.22 at 02:39:02(4885) Dear Jim, Yes, you're correct. Let me try to say it with more precison: If you consider that all taxa are a somewhat stable assembly of genes that were transfered mainly in a "vertical" way in recent times, the best hypotesis we have now for the duckweeds is that they are very specialized forms of the assembly of genes we use to call aroids. They share very similar sequence of cpDNA genes we suppose that are homologous and they are also very similar if we compare the effect of restriction enzimes at the total DNA (nuclear + plastid). Since we don't know any other thing that could be considered better than DNA to show relationship without "morphogenetic black boxes", all this evidence make us believe that aroids+duckweeds can be considered a good taxonomic group together. I know there are lots of strong limitations (like reticulation, lost genetic information, possibility of "lamarckist genes", horizontal transference, etc), but I think it is the best information we have. Maybe, in the future, we will be able to travel back in the time and see different stages of evolution of the Araceae. Maybe we will discover that we will never now the true story of evolution (because it is unique and most evidences are lost) so the taxonomy will be deliberately artificial! (Hey, that will be really good... For the first time after Darwin's era, we will be able to be sure about our taxonomic concepts). Ok, I think I can't be more precise than this by now. I still can refine my concepts, but my poor English is already lacking! Maybe if I could write in Portuguese... :o) +More Best wishes, Eduardo. >Eduardo, > >I think you are correct in all you have said about today's knowledge of the >duckweeds. What "tomorrow" holds is another story! > > Jim Langhammer > > > > ________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com

From: DeniBown at aol.com on 2000.06.22 at 22:36:26(4888) Phew! Now I know no one is going to get shot at, I'll come out from under the bed and say that in the revised edition of Aroids - Plants of the Arum Family (to be published in September) I treat duckweeds as aroids and explain (in layperson's terms but with scientific references) the whys and wherefores of this fascinating taxonomic change. Thank you, Eduardo, for risking life and limb in giving us your lucid comments on the subject. I have always thought that the Araceae is the most mind-boggling family of plants on this planet, and now that it embraces the gigantic Amorphophallus titanum and miniscule Wolffia microscopica, no one can question it - unless to wonder if they are from another planet after all! Deni Bown (lurker)

From: Aroideae at aol.com on 2000.06.23 at 23:47:34(4897) I'm another one who very much enjoyed eduardo's very informative posting! i'm hungry for more. now, I cannot resist asking!! What is Wolffia microspopica? +More Lynn Hannon <<< under the bed and say that in the revised edition of Aroids - Plants of the Arum Family (to be published in September) I treat duckweeds as aroids and explain (in layperson's terms but with scientific references) the whys and wherefores of this fascinating taxonomic change. Thank you, Eduardo, for risking life and limb in giving us your lucid comments on the subject. I have always thought that the Araceae is the most mind-boggling family of plants on this planet, and now that it embraces the gigantic Amorphophallus titanum and miniscule Wolffia microscopica, no one can question it - unless to wonder if they are from another planet after all! Deni Bown (lurker) >>

From: Dean Sliger deanslgr at juno.com> on 2000.06.24 at 03:23:45(4901) On Fri, 23 Jun 2000 18:47:34 -0500 (CDT) Aroideae@aol.com writes: > I'm another one who very much enjoyed eduardo's very informative > posting! +More > i'm hungry for more. now, I cannot resist asking!! What is Wolffia > microspopica? > > Lynn Hannon Lynn -- The common name is "watermeal." As I recall, Wolffia is the world's smallest flowering plant. Looks like bright green poppy seeds floating on the water. I've had it get 1/2" or more thick in aquariums, where one has to be careful that it doesn't get sucked up into a filter, eaten by fish or snails, or overwhelmed by it's larger "cousins." I've carefully kept Wolffia going for years in cultivation but, despite rapid vegetative reproduction, I just can't imagine how this plant survives in the wild! Dean

From: Aroideae at aol.com on 2000.06.25 at 00:27:46(4908) dean--- thankyou for the information! aroids are amazing! no wonder we're 'hooked'. lynn +More << Lynn -- The common name is "watermeal." As I recall, Wolffia is the world's smallest flowering plant. Looks like bright green poppy seeds floating on the water. I've had it get 1/2" or more thick in aquariums, where one has to be careful that it doesn't get sucked up into a filter, eaten by fish or snails, or overwhelmed by it's larger "cousins." I've carefully kept Wolffia going for years in cultivation but, despite rapid vegetative reproduction, I just can't imagine how this plant survives in the wild! Dean >>

From: StellrJ at aol.com on 2000.07.07 at 23:42:34(5007) In a message dated 6/23/00 11:24:17 PM Eastern Daylight Time, deanslgr@juno.com writes: << I've carefully +More kept Wolffia going for years in cultivation but, despite rapid vegetative reproduction, I just can't imagine how this plant survives in the wild! >> Where have you seen it in the wild? The larger genus, Lemna, I tend to see in very shallow waters, even ephemeral puddles, where there are no larger plants nor fish. Never having seen Wolffia, I can only speculate, but I suspect is is an extreme specialist, surviving in places no competitior can reach. Jason Hernandez Naturalist-at-Large

From: Lewandjim at aol.com on 2000.07.08 at 02:38:36(5014) In a message dated 07/07/2000 8:00:11 PM Eastern Daylight Time, StellrJ@aol.com writes: << << I've carefully +More kept Wolffia going for years in cultivation but, despite rapid vegetative reproduction, I just can't imagine how this plant survives in the wild! >> Where have you seen it in the wild? The larger genus, Lemna, I tend to see in very shallow waters, even ephemeral puddles, where there are no larger plants nor fish. Never having seen Wolffia, I can only speculate, but I suspect is is an extreme specialist, surviving in places no competitior can reach. Jason Hernandez Naturalist-at-Large >> Hi Jason, We have quite a few Lemnaceae native here in Michigan. Almost all seem to like quiet back-waters of ponds and lakes where they grow happily entangled among large plants like Nuphar, Nymphaea, Typha, etc. I have seen a Wolffia sp. growing with Spirodela polyrhiza and both Lemna minor and Lemna trisulca - all in the same pond. Jim Langhammer

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