Freethought & Rationalism Archive

Doubting Didymus · 11-21-2002, 07:16 PM

Quote:

Interestingly, Linneaus thought that Venus Flytraps just held insects temporarily, and then nicely opened up and let them go.

Ha! Hahaha. Venus flytraps were originally designed as hug-vendors for lonely depressed insects. Insects that felt a little blue, like the world just doesn't care, or insects that felt as though they were tiny and insignificant could just nuzzle up to a venus flytrap and get a big wet comforting hug. Praise be!

Unfortunately they have now gone horribly wrong and become death machines. Imagine the first post fall depressed insect hovering in for his hug and a theraputic chat ("Doctor, ever since the woman ate that fucking plum, I suddenly feel the urge to use my massive sharp rostrum to peirce my neighbors exoskeleton and suck out his innards"), and he gets digested alive instead. Praise be!

theyeti · 11-22-2002, 07:13 AM

Quote:

Originally posted by Nic Tamzek:
<strong>
Interestingly, Linneaus thought that Venus Flytraps just held insects temporarily, and then nicely opened up and let them go.
</strong>

That is funny. BTW, can you relate what Linneaus' rationale was for this behavior? I find it interesting because post-Darwin we see the teleos of all functioning organs as being geared to the survival and/or reproduction of the organism in which they reside (or to be more specific, the genes from which the functions originate). If we were to take Linneaus' hypothesis seriously today, we would want to know what benefit the Flytraps were getting out of temporarily trapping insects; in the absence of such benefit, we would consider this behavior inconsistent with what we know of nature. I suspect that Linneaus probably didn't think in these terms, which shows us the difference between teleological thinking pre and post Darwin. It also shows how Darwinian evolution could be falsified, but so far hasn't.

theyeti

Nic Tamzek · 11-23-2002, 04:06 PM

Quote:

Originally posted by theyeti:
That is funny. BTW, can you relate what Linneaus' rationale was for this behavior? I find it interesting because post-Darwin we see the teleos of all functioning organs as being geared to the survival and/or reproduction of the organism in which they reside (or to be more specific, the genes from which the functions originate). If we were to take Linneaus' hypothesis seriously today, we would want to know what benefit the Flytraps were getting out of temporarily trapping insects; in the absence of such benefit, we would consider this behavior inconsistent with what we know of nature. I suspect that Linneaus probably didn't think in these terms, which shows us the difference between teleological thinking pre and post Darwin. It also shows how Darwinian evolution could be falsified, but so far hasn't.

theyeti

Here is what I know about Linnaeus on VFTs, from Juniper, Robins, and Joel, The Carnivorous Plants, London: Academic Press, 1989, p. 15:

Quote:

In 1769 Ellis, who acheived other fame from his better known text 'Directions for Bringing Over Seeds and Plants from the East Indies' (1770) sent Linnaeus a drawing and a good description of a plant to which he had given the name of Dionaea; the name being derived from one of the synonyms for Venus. He stated that he had received the specimen from Peter Collinson who had been given it by John Bartram of Philadelphia, botanist to the late king. Ellis wrote to Linnaeus:

'...Nature may have some views toward its nourishment in forming the upper join of its leaf like a machine to catch food: upon the middle of this lies the bait for the unhappy insect that becomes its prey...the two lobes rise up, grasp it fast, lock the rows of spines together, and squeeze it to death...three small erect spines are fixed near the middle of each lobe, over the glands, that effectually put an end to all its struggles.'

The overall description is so accurate as to indicate, at least second-hand, that it was based on field observation; although certain details, in particular the role of the spines, were erroneous [they are actually trigger hairs -- nt]. Enoromous interest was generated by this extraordinary little plant and even the President of the United States, Thomas Jefferson, reported in his correspondance that he had collected and distributed Dionaea plants from Charleston in 1787 (see Boyd, 1955) [They sure don't make them presidents like they used to -- nt]. Linnaeus, however, with all the facts in front of him, but only dried specimens to study, refused to believe the obvious. He wrote (see Smith, 1821 and Darwin, 1888, p. 243) that as soon as the insects ceased to struggle the leaf lobes opened up and let them go.

Unfortunately it appears that only the 1st edition of Insectivorous Plants is online, and not the 1888 2nd edition (revised by his son Francis Darwin), so I'm not sure what Darwin(s) said about Linnaeus on p. 243.

We shouldn't be too hard on Linnaeus however, it appears that he did recognize the VFT as something special:

<a href="http://30.1911encyclopedia.org/V/VE/VERA_A_.htm" target="_blank">source</a>

Quote:

VENUS’S FLY-TRAP (Dionaea muscipula), a remarkable insectivorous plant, a native of North and South Carolina, first described in 1768 by the American botanist Ellis, in a letter to Linnaeus, in which he gave a substantially correct account of the structure and functions of its leaves, and even suggested the probability of their carnivorism. Linnaeus declared it the most wonderful of plants (miraculum naturae), yet only admitted that it showed an extreme case of~ sensitiveness, supposing that the insects were only accidentally captured and subsequently allowed to escape. The insectivorous habit of the plant was subsequently fully investigated and described by Charles Darwin in his book on insectivorous plants.

And despite working in a creationist framework, Linnaeus began to realize that species weren't constant and began to move the created "kinds" up to higher taxonomic levels.

And he was not alone; many early naturalists missed or misinterpreted carnivory in plants:

(Juniper et al., p. 12)

Quote:

Although occasionally not without unintentional humour, early studies of carnivorous plants do not, on the whole, reflect much credit on the observational powers of the early naturalists. There often seems to have been a marked reluctance on the part of otherwise highly respected scientists to admit to a carnivorous role for plants. This reluctance has a parallel in the far more significant inhibitions of many botanists, roughly over the same period, to admit to the sexual functions of flowers or even to the existence of sexual systems in plants at all (Delaporte, 1982; Mayr, 1983). There can also be no doubt that many competent artists failed, in their beautiful depictions, to record the dead insects on the sticky surfaces of, for example, Pinguicula, Drosera and Drosophyllum. Only Gerard (1633) left a few midges or gnats on his drawings of sundews, but he failed to realize their significance.

In the brief historical account that follows we have sought to indicate not only when the individual genus or species was first described but, more important to our argument, when its remarkable nature was first recognized. This understanding may come very much later than the actual discovery of the plant, and the year or spread of years is given after the generic name in the sub-headings.

[I will give the sub-headings; note that 1875 is when Insectivorous Plants was published]

Drosera 1780-1875 (The sundews)

Sarracenia 1737-1791 (Pitcher-plant or Trumpet-leaf)

Dionaea 1769-1834 (Venus's Fly-trap)

Cephalotus follicularis 1800-1823 (Australian pitcher-plant)

[...The rest of the list has no impressive lags except for Nepenthes, discovered in the mid-17th century...]

Nepenthes (Pitcher-plant: Monkey's cup, Dutchman's pipe)

[...]
However, as we have seen, Linnaeus was not inclined to accept the carnivorous nature of plants and, despite many beautiful depictions by Fitch in Curtis' Botanical Magazine in the first half of the nineteenth century, not until 1858 was the first tentative suggestion made as to its carnivorous proclivities. Hooker W.J. (1858) writes '...pitcher..no doubt is a great provision of nature for decoying and for the destruction of insects.'

[WJ Hooker was the father of Darwin's buddy JD Hooker BTW]

I'm doing a writeup of the evolution of carnivorous plants, so I've got the refs handy.

Some new stuff that turned up on a web search:

<a href="http://bestcarnivorousplants.com/aldrovanda/papers_online/Fossil.htm" target="_blank">Fossil seed and pollen record of Aldrovanda</a>

<a href="http://www.bestcarnivorousplants.com/" target="_blank">More C.P. Newsletter articles</a>

J.D. Hooker on Darwin's Insectivorous Plants: <a href="http://www.jdhooker.org.uk/" target="_blank">Address of Sir Joseph Dalton Hooker, C.B., K.C.S.I. The President,
Delivered at The Anniversary Meeting of The Royal Society, on Saturday, November 30, 1878.</a>

Good pics and recent discoveries concerning the in-again, out-again sorta-carnivore Roridula: <a href="http://www.calacademy.org/calwild/sum98/plant.htm" target="_blank">http://www.calacademy.org/calwild/sum98/plant.htm</a>

Obscure tidbits on Linnaeus, Darwin, and Dionaea:

<a href="http://www.math.auckland.ac.nz/~waldron/NZCPS/Auckland-newsbriefs/12.4.html" target="_blank">Origin of the "steel trap" analogy for VFTs</a>

<a href="http://www.dickinson.edu/~nicholsa/Romnat/dartrap.htm" target="_blank">Erasmus Darwin on the VFT</a>

<a href="http://www.rc.umd.edu/praxis/ecology/nichols/nichols_notes.html" target="_blank">Some stuff on sex and botany for Linnaeus and Darwin</a>

Looks like Linnaeus didn't get Aldrovanda right, either -- whereas Darwin just got himself confirmed by 21st-century science (although this article overplays it a bit):

Quote:

Darwin’s Insight

When Carolus Linnaeus, the founder of modern taxonomy, was naming plants in the 1700s, he surmised that the waterwheel’s whorls of snap-traps were little air balloons that helped the rootless plant float in water. (Indeed, his name for the species, Aldrovanda vesiculosa, attests to the idea of air vesicles). Darwin was the first scientist to make the connection with carnivorous plants, describing the waterwheel as “a miniature, aquatic Dionaea [Venus’ flytrap].” Darwin carefully studied live specimens of the plant and strongly suspected that it used its “air balloons” to capture tiny marine animals.

Botanists subsequently proved that waterwheel’s whorls did indeed consist of prey-catching snap-traps, but many still believed the plant’s resemblance to Venus’ flytrap was coincidental. For much of the 20th century, botanists debated exactly how carnivorous plants had evolved, and in what order. Many researchers concluded that the snap-traps of Venus’ flytrap and waterwheel were an example of convergent evolution—nature’s way of creating the same mechanism twice in unrelated organisms.

The sole phylogenetic systematic study of waterwheel’s relationship to other carnivorous plants, conducted at the University of North Carolina in 1994, suggested that waterwheel was most closely related to the sundew. (Phylogenetic systematics is a taxonomic system that links organisms based on shared characteristics.) This seemed logical, because its flowers strongly resemble those of the sundew. The sundew, however, uses sticky globules called “flypaper traps” instead of snap-traps to capture its prey. The North Carolina study implied that the sundew’s flypaper mechanism may have evolved from the waterwheel’s snap-traps.

Cameron thought this was unlikely, since other evidence suggested that the trigger hairs on a Venus’ flytrap were themselves derived from flypaper trap tentacles. So he found himself asking the classic evolutionary question: which came first?

A New Genetic Approach to the Question

To settle the issue, Cameron and his team at The New York Botanical Garden conducted the first molecular evolutionary study of this question based on carnivorous plants’ genetic similarities, rather than on their outward appearances. Working with DNA sequences from each genus of carnivorous plants, the researchers constructed a family tree by comparing several genes. The basic idea was that the greater the genetic similarity between two plants, the more closely they are likely to be related.

Taken all together, the team’s results showed that Venus’ flytrap and waterwheel were each other’s closest relative, strongly supporting the idea that these plants have a common ancestor and that snap-traps evolved only once in the history of plants. Data on these plants’ genetic relationship with other carnivorous plant species also showed, as Cameron had suspected, that snap-traps evolved from flypaper traps, not the other way around.

Intriguingly, field botanists have reported that when Venus’ flytrap’s habitat becomes flooded, the plant is still able to grow and capture prey. “Thus,” says Cameron, “it isn’t hard to imagine a common terrestrial ancestor adapting to life in the water and, over time, evolving into the waterwheel plant.”

Nic Tamzek · 02-25-2003, 03:51 AM

I was reading the carnivorous plants book Savage Garden by D'Amato and came across a pic of a weird-looking Nepenthes pitcher of Nepenthes infundibuliformis, aka N. eymai.

Strangely the pitcher was much simpler than your average Nepenthes pitcher, and furthermore was described as basically being a funnel with *sticky* (rather than slippery) sides. The sticky juices accumulated as a kind of sticky syrup in the bottom of the funnel.

Here is a typical Nepenthes pitcher (actually, just the lower pitcher of N. eymai -- most Nepenthes are dimorphic with different-looking lower pitchers (for ground/crawling insects) and upper pitchers (for flying insects)):

(this is a potted version of the plant, actually there is an upper pitcher in the background)

Another version:

But here is the upper pitcher:

(source page)

Why I am making this random post:

The significance of this comes from recent phylogenetic evidence that most pitcher-plants appear to have adhesive-trap carnivorous plants as either basal (as with Nepenthes) or sister (as with Sarraceniales) groups. The question of how a sticky-trap could convert to a pitfall trap has not, AFAIK, actually been addressed in any literature anywhere. Pinguicula gave some hints, they are adhesive traps but many of them display significant rolled-up morphology:

...but the upper pitcher of Nepenthes eymai would appear to give another analogous intermediate. I have no idea if there is any phylogenetic sequencing done on Nepenthes eymai yet, in general there appears to be very little info. about the plant available, so this pitcher form could just as well be derived as basal. But either way it does show the possibility of a transitional stage.

At the other end of the scale, here is an "advanced" pitcher form:

...must give them bugs nightmares.

PS: Here is a somewhat-closely related vine that is only carnivorous (sticky glands on the tendrils) for part of its lifetime, during the juvenile growth phase. Most online pictures suck because in the wild it is a 100-foot long tropical vine (endangered, BTW) and it does very poorly in cultivation (no reproduction or, usually, carnivory).

(source)

We now return you to your regularly scheduled evo-creo debating...

PPS: This thread appears somewhat messed up, the tags are appearing in the previous posts. This was occurring before this latest post BTW.

Vorkosigan · 02-25-2003, 05:39 AM

Nic! Great post!

What's the name of the carnivorous vine?

Coragyps · 02-25-2003, 11:14 AM

Quote:

Why I am making this random post

And I thought for a minute there it was to get me all excited about Douglas having some new word on King Juan Carlos, the Antichrist......

Tom Ames · 02-25-2003, 03:54 PM

Quote:

Originally posted by Nic Tamzek
[B]I was reading the carnivorous plants book Savage Garden by D'Amato and came across a pic of a weird-looking Nepenthes pitcher of Nepenthes infundibuliformis, aka N. eymai.

Nic,

I just visited Peter D'Amato's nursery ("California Carnivores") last week, and WOW, was it impressive!

I bought a Cape Sundew (Drosera capensis), a bladderwort (Utricularia livida) and a Purple Pitcher plant (Sarracenia purpurea). They're not as dramatic as those in your pictures, but beautiful nonetheless.

Makes me want to get back into systematics.

(D'Amato's discussion of evolution in his book leaves a lot to be desired, but what're you gonna do?)

Nic Tamzek · 02-25-2003, 04:29 PM

To various people:

The vine is Triphyophyllum peltatum, from West Africa.

Where is California carnivores, anyhow? I saw the address but I never got around to figuring out if it was northern California or what.

Tom, actually I did a paper for a class on CP evolution, give me an email and I will send it to you, I think it should have a future somewhere although I haven't been able to work on it this quarter. D'Amato is not a serious thinker on the evolutionary side of things, although his book has lots of nice pics.

nic

Nic Tamzek · 04-12-2003, 04:38 PM

Bump. Weird, I added some new notes on this topic to the thread in my bookmark, but that was on an old version of the thread, located here:

http://www.iidb.org/cgi-bin/ultimate...&f=58&t=000967

(...which has the original formatting for the old posts which is nice)

Anyway I just wanted to post some articles that came up as "related" to a carnivorous plants article.

=====

Quote:

Plant Mol Biol 2000 Jan;42(1):45-75

Contributions of plant molecular systematics to studies of molecular evolution.

Soltis ED, Soltis PS.

Department of Botany, Washington State University, Pullman 99164-4238, USA.

Dobzhansky stated that nothing in biology makes sense except in the light of evolution. A close corollary, and the central theme of this paper, is that everything makes a lot more sense in the light of phylogeny. Systematics is in the midst of a renaissance, heralded by the widespread application of new analytical approaches and the introduction of molecular techniques. Molecular phylogenetic analyses are now commonplace, and they have provided unparalleled insights into relationships at all levels of plant phylogeny. At deep levels, molecular studies have revealed that charophyte green algae are the closest relatives of the land plants and suggested that liverworts are sister to all other extant land plants. Other studies have suggested that lycopods are sister to all other vascular plants and clarified relationships among the ferns. The impact of molecular phylogenetics on the angiosperms has been particularly dramatic--some of the largest phylogenetic analyses yet conducted have involved the angiosperms. Inferences from three genes (rbcL, atpB, 18S rDNA) agree in the major features of angiosperm phylogeny and have resulted in a reclassification of the angiosperms. This ordinal-level reclassification is perhaps the most dramatic and important change in higher-level angiosperm taxonomy in the past 200 years. At lower taxonomic levels, phylogenetic analyses have revealed the closest relatives of many crops and 'model organisms' for studies of molecular genetics, concomitantly pointing to possible relatives for use in comparative studies and plant breeding. Furthermore, phylogenetic information has contributed to new perspectives on the evolution of polyploid genomes. The phylogenetic trees now available at all levels of the taxonomic hierarchy for angiosperms and other green plants should play a pivotal role in comparative studies in diverse fields from ecology to molecular evolution and comparative genetics.

Quote:

Biologist (London) 2002 Dec;49(6):245-9

Carnivorous plants--classic perspectives and new research.

Rice B.

The Nature Conservancy, Davis, USA. Barry@sarracenia.com

The ranks of known carnivorous plants have grown to approximately 600 species. We are learning that the relationships between these feeders and their prey are more complex, and perhaps gentler, than previously suspected. Unfortunately, these extraordinary life forms are becoming extinct before we can even document them

Quote:

Am J Bot 1999 Oct;86(10):1382

Structure and development of the pitchers from the carnivorous plantNepenthes alata (Nepenthaceae).

Owen TP Jr, Lennon KA.

Department of Botany, Connecticut College, 270 Mohegan Avenue, New London, Connecticut 06320-4196.

The pitchers of the tropical carnivorous plant Nepenthes alata are highly specialized organs for the attraction and capture of insects and absorption of nutrients from them. This study examined the structure and development of these pitchers, with particular focus on the nectaries and digestive glands. Immature pitchers developed at the tips of tendrils and were tightly sealed by a lid structure that opened during the end of pitcher elongation. Opened pitchers exposed a ridged peristome containing large nectaries. Like other members of the genus, a thick coating of epicuticular waxy scales covered the upper one-third of the pitcher. Scattered within this zone were cells resembling a stomatal complex with a protruding ridge. Cross sections showed that this ridge was formed by asymmetric divisions of the epidermal cells and lacked an underlying pore. The basal region of the trap had large multicellular glands that developed from single epidermal cells. These glands were closely associated with underlying vascular traces and provided a mechanism for supplying fluid to closed immature pitchers.

Chiron · 04-12-2003, 10:01 PM

[QUOTE]Originally posted by Kosh

Quote:

Originally posted by Gregg:
<strong>

Where do people learn to reason like this? Is there a School of Bad Logic somewhere?</strong><hr></blockquote>

Good logic is probably more a learned trait than we'd like to admit. However, I think this thread is yet another excellent example how the typical creationist argues.....

out of ignorance.

Argumentum ad Ignorance

(is there a better latin word for ignorance?)

Just thought I may as well chip in with the two best translations for "Argument from Ignorance" I can think of:
1) argumentum ab inscientiae (connotations of ignorance and inexperience)
2) argumentum ab inscitiae (connotations of ignorance, na�vet� (or naivety ;) and lack of skill)

I don't have much to add to the actual discussion, but since I'm much more versed in Latin than biology, no harm in clarifying things a bit.

-Chiron
For future Latin needs, try http://www.nd.edu/~archives/latgramm.htm and http://catholic.archives.nd.edu/cgi-bin/lookdown.pl
Use the first to translate from Latin to English, and the second to translate English to Latin.

02-25-2003, 03:51 AM	#34
Nic Tamzek Senior Member Join Date: Jan 2002 Location: California Posts: 646	Random thought... I was reading the carnivorous plants book Savage Garden by D'Amato and came across a pic of a weird-looking Nepenthes pitcher of Nepenthes infundibuliformis, aka N. eymai. Strangely the pitcher was much simpler than your average Nepenthes pitcher, and furthermore was described as basically being a funnel with sticky (rather than slippery) sides. The sticky juices accumulated as a kind of sticky syrup in the bottom of the funnel. Here is a typical Nepenthes pitcher (actually, just the lower pitcher of N. eymai -- most Nepenthes are dimorphic with different-looking lower pitchers (for ground/crawling insects) and upper pitchers (for flying insects)): (this is a potted version of the plant, actually there is an upper pitcher in the background) Another version: But here is the upper pitcher: (source page) Why I am making this random post: The significance of this comes from recent phylogenetic evidence that most pitcher-plants appear to have adhesive-trap carnivorous plants as either basal (as with Nepenthes) or sister (as with Sarraceniales) groups. The question of how a sticky-trap could convert to a pitfall trap has not, AFAIK, actually been addressed in any literature anywhere. Pinguicula gave some hints, they are adhesive traps but many of them display significant rolled-up morphology: ...but the upper pitcher of Nepenthes eymai would appear to give another analogous intermediate. I have no idea if there is any phylogenetic sequencing done on Nepenthes eymai yet, in general there appears to be very little info. about the plant available, so this pitcher form could just as well be derived as basal. But either way it does show the possibility of a transitional stage. At the other end of the scale, here is an "advanced" pitcher form: ...must give them bugs nightmares. PS: Here is a somewhat-closely related vine that is only carnivorous (sticky glands on the tendrils) for part of its lifetime, during the juvenile growth phase. Most online pictures suck because in the wild it is a 100-foot long tropical vine (endangered, BTW) and it does very poorly in cultivation (no reproduction or, usually, carnivory). (source) We now return you to your regularly scheduled evo-creo debating... PPS: This thread appears somewhat messed up, the tags are appearing in the previous posts. This was occurring before this latest post BTW.

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search

02-25-2003, 05:39 AM	#35
Vorkosigan Contributor Join Date: Jan 2001 Location: Barrayar Posts: 11,866	Nic! Great post! What's the name of the carnivorous vine?

02-25-2003, 04:29 PM	#38
Nic Tamzek Senior Member Join Date: Jan 2002 Location: California Posts: 646	To various people: The vine is Triphyophyllum peltatum, from West Africa. Where is California carnivores, anyhow? I saw the address but I never got around to figuring out if it was northern California or what. Tom, actually I did a paper for a class on CP evolution, give me an email and I will send it to you, I think it should have a future somewhere although I haven't been able to work on it this quarter. D'Amato is not a serious thinker on the evolutionary side of things, although his book has lots of nice pics. nic

Freethought & Rationalism Archive

The archives are read only.