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Primitive carnivory analyzed

Take a close look at photos of plants having sticky defensive glands such as Stylidium. Captured insects are stuck on the glands and not even in contact with the leaf surface.
There is a prevalent misconception about such sticky glands. The retentive glands of pseudo-carnivorous plants resemble those of Byblis and Pinguicula. Unlike in Drosera, the retentive glands of these plants only secrete glue and do not absorb. Absorption in Byblis and Pinguicula is carried out by the leaf surface through the digestive fluid secreted there.
Carnivory in Byblis linifolia is rather primitive. I have observed while growing the plant that there is no secretion of digestive fluid from the leaf surface unless the plant is in high humidity. Also note that the majority of the retentive glands are too long stalked and insects caught on them will be suspended well above the leaf surface and so unavailable for digestion. I suspect that these excessively tall retentive glands are primarily defensive. It seems to me that carnivory in this species is more of a side benefit of the plant’s defensive weaponry.
 
Interesting idea. It seems like the plants evolved from having using hairs as defense to using hairs to acquire more nutrients through capturing prey. Pinguicula are most closely related to Utricularia and Genlisea though, so maybe something different happened with those.
 
Interesting idea. It seems like the plants evolved from having using hairs as defense to using hairs to acquire more nutrients through capturing prey. Pinguicula are most closely related to Utricularia and Genlisea though, so maybe something different happened with those.

Thanks. Yes, the glandular hairs surly started out deterring plant eaters in both Byblis and Pinguicula. Although, these two probably do not have a common ancestor: Parallel Evolution. Note that butterworts have glandular hairs on their flowers stalks also which are not for carnivory.

I am studying a Monkey Flower (Mimulus sp.) found here in Southern California which intriguingly has another carnivorous characteristic. In addition to glandular hairs which capture insects, this plant is also able to take nutrition from them. The leaves (not the glandular hairs) secrete something analogous to digestive fluid. As in Byblis, this fluid is only secreted during high humidity. The fluid is from guttation which forms the morning dew so often seen on plants. Most curious though, the fluid does seem to digest. I am thinking this might be another defense mechanism. And if so, this is a case of carnivory only by accident; which is the most primitive level. Quasi (or seemingly) Carnivorous is a fitting term.
 
Hmm, I wonder if that plant is closer to being carnivorous than Ibicella or Proboscidea, which also have a reputation as being quasi-carnivorous. I also wonder why the plants only secrete those fluids in high humidity. It doesn't seem like they live in places which get very humid.
 
Good point; they do not. Perhaps a better term for those plants might be Pretend Carnivorous?
 
Recently I have been growing and studying another Monkey Flower from here in Southern California which is new to me. This one has the strongest reaction I have seen to being fed. See in my photo it secretes a fluid on insect portions placed upon the leaves, just as a butterwort would. Thanks to Naomi Fraga of Rancho Santa Ana Botanic Gardens for identifying the plant as Erythranthe nasuta.
 

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Perhaps a new genus to be added to the list then?
Also, as per personal observances and articles in the recent CPN, it's not a primarily humidity-related phenomenon with Byblis secreting digestive fluids, but the time of day. They'll definitely secrete even in lower humidity, but it might not be visible when we're normally looking.
 
I am thinking this might be another defense mechanism. And if so, this is a case of carnivory only by accident; which is the most primitive level. Quasi (or seemingly) Carnivorous is a fitting term.

I also wonder why the plants only secrete those fluids in high humidity. It doesn't seem like they live in places which get very humid.

Couple possible reasons.
1) If the fluids were a defense against fungi like powdery mildew or other organisms which flourish under high humidity conditions, it would be most efficient to produce said fluid when humidity is high and little to none when humidity is low.
2) If the fluids are predominately water (yes, most fluids produced by plants are :) ), then the lack of observable secretions (or only minute amounts as Hawken mentioned he has observed such on Byblis) may simply be the result of high evaporation when humidity is low.

And, of course, even if one of these reasons is spot on for one or more plants in question, it could be for totally different reasons with other species.
 
It sure looks like it’s digesting that fruit fly butt. I’ll have to see if the fluid dissolves gelatin. Right now I’m waiting to see if there is a growth spurt after feeding. You can see one sundew in the cup; there is actually two. One I fed and the other not...
 
  • #10
Very interesting stuff! There are one or two other gland-covered genera/species that I have wondered about as well. I can see where stalked glands would be an effective defence against small insects. It also seems easy for an evolutionary leap to occur enabling the plants that have them to absorb the rotting remains as nutrients or better, to absorb the excreted waste of predatory insects that eat those captured insects. Developing digestive enzymes seems a much tougher development. It all seems so unlikely to me but there it is in the plants we know and love.

I am looking forward to seeing how the monkey flower plant does with the gelatin.
 
  • #11
Very interesting stuff! There are one or two other gland-covered genera/species that I have wondered about as well. I can see where stalked glands would be an effective defence against small insects. It also seems easy for an evolutionary leap to occur enabling the plants that have them to absorb the rotting remains as nutrients or better, to absorb the excreted waste of predatory insects that eat those captured insects. Developing digestive enzymes seems a much tougher development. It all seems so unlikely to me but there it is in the plants we know and love.

I am looking forward to seeing how the monkey flower plant does with the gelatin.

The enzymes may not really be that huge a leap; every cell produces a battery of enzymes already for various functions necessary for everyday life, including various ones that break apart proteins or nitrogenous compounds etc. etc., so what would really be needed is just modification of cells to excrete and absorb specific groups of those enzymes in higher quantity so they can act on compounds outside the cell/plant and then be retrieved.
 
  • #12
Thanks for your interest and thoughts guys. I fed my plants more stuff. There does seem to be digestion going on, but I cannot really tell if it is by bacteria. Also, there is a growth spurt following these forced feedings. I have seen plants in the wild capture insects on their own as well. However, I consider the case of this plant to be merely accidental carnivory: The most primitive level of carnivory.

Bluemax, please do let us know what you learn from species found around your area. This one I have growing now is not very dewy. Another I have grown, Mimulus / Erythranthe tilingii, is super dewy. Springtails (tiny algae eating soil insects) introduced to the growing container were readily captured. E. tilingii is very closely related to E. nasuta. Through hybridization and selection, and maybe a little genetic modification, we could accentuate the natural pre-adaptations and create a new carnivorous plant. Or, maybe there is already a Monkey Flower out there which is truly carnivorous waiting to be found.
 

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  • #13
I will keep my eyes open. I am out in the field often and now I will be looking for monkey carnivores. :bee:
 
  • #14
@Lechenaultia I figure that directed guttation is the first step towards carnivory; dissolving nutrients for absorption. As I have been discussing privately with @bluemax , I discovered the fluid secreted by my monkey flower dissolves gelatin but I don’t think it actually digests it since it does not dissolve egg whites. I noticed captured insects do their business on the leaves; pictured in post #12. The fluid dissolves this and may also release nutrients from within their guts. My monkey flower is carnivorous!
 
  • #15
Unless you're classifying any plant that may absorb nutrients through the leaves as carnivorous (which due to stomatal absorption is a lot of them), I don't think that qualifies. Liquid secretion can also have the purpose of removing contaminants so that debris etc. doesn't bloom bacteria or fungi that may infect the plant, secondarily may permit some absorption of minute nutrients through the stomata, but unless there's evidence of some sort of active enzymatic work (either from the plant or direct symbionts) and that the plant is benefitting clearly from the additional acquisition, evidence is lacking.
 
  • #16
@Lechenaultia I figure that directed guttation is the first step towards carnivory; dissolving nutrients for absorption. As I have been discussing privately with @bluemax , I discovered the fluid secreted by my monkey flower dissolves gelatin but I don’t think it actually digests it since it does not dissolve egg whites. I noticed captured insects do their business on the leaves; pictured in post #12. The fluid dissolves this and may also release nutrients from within their guts. My monkey flower is carnivorous!
Part1/4

Dear FrankenSnyder-san,

Konnichiwa!

Thank you very much for inviting me to a very interesting and nice thread.
The content of the conversation is so advanced that I don't think it's appropriate for me to join this thread, but I'd appreciate it if I could join a little.

The pooling effects I have observed were phenomena that occurred on the leaves of Lindernia cleistandra (KSV) plantlets inside small plastic containers.
Humidity was high because it was in a plastic container.

This work shed has no air conditioning other than the incubation room, so summer temperatures often exceed 40 degrees Celsius. I think the temperature inside the container was terrible / horribly hot. KSV didn't care at all.
I was trying to see if cutting propagation was possible with oasis foam.

I tried feeding to KSV out of curiosity in 2013. The photos were taken in 2013.
 

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  • #17
Part2/4

These photos were taken in 2014 when I was thinking of setting up for shooting.
 

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  • #18
Part3/4

These photos were taken when I actually succeeded in shooting the pooling effect.

In the room next to the bedroom, I used LED lighting and time-lapse software during the day to shoot automatically. I turned off the LED lights at night and turned on the lights when I woke up a couple of times and took pictures.
 

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  • #19
Part4/4

I'm busy this year so I still don't know what I can actually do. We have to work at night too, but maybe I can do something more than during the day.

If possible,
I would like to sow KSV in vitro. TC of KSV is very easy. Acclimatizing is a bit cumbersome because the tissue is soft.

I would like to aseptically place mosquito larvae or the boiled egg whites you mentioned on the KSV leaves to see if the pooling effect occurs.
If the pooling effect occurs, it may be interesting to collect the fluid with a pasteur pipette and place it on a boiled egg.

What do you think of it, FrankenSnyder-san? Please let me know if my English doesn't make sense. I will try to edit.

Kind regards from the Far East
 
  • #20
I like the idea of drawing off any pooling fluid and applying that to egg white to see if it breaks down. 'A simple way to determine if it attacks protein without needing chemical analysis. It might be useful to do a control with pure water also applied to egg white.
 
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