Why aren't Darlingtonia posts under "Quasi-carnivr

[Mr. Darlington]

Since it is very clear that Darlingtonia has no innate enzyme activity, and therefore does not meet the strict definition of a carnivorous plant (as per Schlauer and others), why are not all the post related to that species placed on the "Quasi-carnivorous" board?

 

[Tony Paroubek]

I am not up on exactly what every plant produces but aren't there other plants that don't produce enzymes either? Like Heliamphora and S. purpurea?

I think alot of people disagree that enzyme production is a necessary requirement. More importantly in my opinion, does the plant actively attract, trap, receive benefit from trapped prey remains? Darlingtonia is highly specialized to attract trap and kill insects specifically to obtain nutrients as they decompose. The other plants listed in quasi-carnivorous don't have any specialized methods to attract insects and their capture is not clearly purposefull to kill and obtain nutrients as a result.

Tony

 

[schloaty]

Also, at least in the case of S. purpurea, the plant harbors bacteria that work to break down the carcasses. These bacteria provide the same function as ensymes (thought not produced by the plant).

 

[Mr. Darlington]

S. purpurea at least produces some enzymes at the first stages of the pitcher's life; later the enzyme activity stops and other methods of breakdown occur. Darlingtonia also relies on bacteria and other organisms to break down prey into usable elements, but no inherent enzyme production has been demonstrated.

I am not sure about the current thinking on Heliamphora. It seems likely that at least some produce enzymes.

Roridula is not considered carnivorous in the strict sense, but it is clearly adapted to trap and use insects, albeit with the help of a commensal insect or spider. It is a good parallel for Darlingtonia "quasi-carnivorous" (or perhaps para-carnivorous is a better term). In both cases they shoud be discussed as not truely CP.
.

 

[Tony Paroubek]

Suit yourself... Call them both quasi carnivorous if you want. To me Darlingtonia has evolved much more elaborate mechanisms to lure insects for the sole purpose of obtaining nutrients than Roridula. If it were not for the companion bugs on Roridula the sticky secretions would serve only as protection from insects eating the plant.

 

[CP2k]

Check out this CPN article:Carnivory in Byblis revisited II: The Phenomenon of Symbiosis on Insect Trapping Plants by Siegfried Hartmeyer
Personally, I consider Roridula to be carnivorous.

 

[sarracenia]

I think some people take the term carnivorous too seriously. It is true that some plants don't strictly fall under the "Webster's" definition of carnivorous, one must remember that the definition was developed with animals in mind. And while there is the order Carnivora in the animal kingdom, there is no such classification in the plant kingdom. It is simply an informal term for plants that obtain nourishment from captured animals. Perhaps a scientific term needs to be created to cover these plants, from the venus fly-traps to the cobra lilies, to the shepherd's purses. Maybe one has, that I just haven't heard yet. It certainly isn't 'carnivorous'.

 

[sarracenia]

To answer the genteman's, or gentlewoman's question:

I'm not responsible for setting these boards up, but I assume that Darlingtonia posts are included with Sarracenia and Heliamphora because they are all pitcher plants in the Sarraceniaceae, and therefore logically placed in that subforum.

Why Cephalotus is included, I don't know.  But I would guess that it wouldn't get enough posts to justify its own sub-forum, and the pitcher plant forum is as logical as any to place it in.

 

[CP2k]

Another interesting thing about Roridula is that the "glue" produced by this plant is very strong from what I have read. Here are some pics of Roridula with prey from Martin's website(www.drosphyllum.com): R.gorgonias with prey
R.dentata with prey
Another pic

 

[Mike King]

To call the Darlingtonia plant a quasi-carnivore is a nonsense. OK it may not produce enzymes, but does benefit by deliberately attracting,trapping, killing and finally absorbing nutrients DIRECTLY from captured prey where roridula does not..

 

[CP2k]

Hi Mike,

What do you mean by "Directly"? Do you mean that Roridula is quasi-carnivorous because the Pameridea insects digest the prey or because the nutrients are absorbed via the stomata?

 

[schloaty]

Guys, with regards to these "quasi-carnivores," what's the difference between having bacteria doing the digestion or a larger organism (assassin bug) doing the digestion?

I think you can call a plant carnivorous if it has evolved to attract, trap and kill with the intent of getting nourishment from the carcass. The means by which the plant attains the nutrients is mute. The cobra attract, trap and kill. I know Roridulas trap and kill, but do they lure? I'm unfamiliar with this genus, so I don't know if they have a sent or something that attracts prey.

 

[Darcie]

I do believe that the issue is sort of silly, because the newer definitions state that they must trap and kill.  With an attempt at attrating OR opertunistic traping.  If a relative of the plant produces digestive enzyms or the plant is host to a symbiotic organism that helps with the digestion it counts as being able to digest prey.  That is why some of the older suedo's are being reclassified right now

 And it should also be noted, the key feature looked for currently is the presence of an adaptation within the trap to let the plant absorb the nutrients.  At least according to my 2003 addition of my GIGA bio book.  If I had it here I would quote, but it's at school...

... I've also read no one has ever looked at Cobra's morphology enough to determin what the inside of the traps can do, so it may actually secreat digestive enzyms opertunistically and we just don't know it yet

 

[nepenthes gracilis]

Well If a plant is luring bugs to it regardless of what it is and it benefits from them after they have been broken down into simpler elements then I say it qualifys as carnivorous. So you can look at my theory as this:

Qualities of being a CP:

1.) Plant must lure some sort of potential prey.
2.) Plant must have a way to digest/break down prey.
3.) Plant must benefit from prey.
4.) Plant must continue carnivory.

My .02 cents.

 

[CP2k]

Hi Schloaty,

Roridula lures its prey in the same way that Drosera lures its prey. I do not recall either genera utilizing scent as a lure, but I may be wrong. Roridula seems to attract bugs quite well as evidenced by the photos in my previous posts. I have heard of cases where growers had to remove the insects trapped on Roridula to prevent fungus when they did not have any Pameridea bugs.