Carnivorous Plants Website
Carnivorous Plants in the Wilderness
by Makoto Honda



Carnivorous Plants
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Anatomy of Carnivory

Under construction  ------------------  Anatomy of carnivory

2017-March-20

 

For carnivory to take effect, there must be contact between leaf and prey. If a fly lands on a leaf and a moment later flies away, the contact is not sufficient. A fly must be persuaded to stay for a period during which the digestion can take place. 

 

The first step in the sequence of events leading to successful carnivory is a lure (visual/olfactory/food) that brings prey to physical proximity. Capture -- forced retention -- follows. Digestion then starts that decomposes the prey -- the protein in the animal's body is broken down into amino-acids. The digestion proceeds with plant's own enzyme or with the help of other commensal organisms. 

 

The products of digestion are absorbed into the leaf and are carried to the growth site of the plant. The main nutrients selectively absorbed by carnivorous plants are nitrogen (N) and phosphorus (P) but some other elements required in trace amounts such as potassium (K: Kalium) and magnesium (Mg) are also utilized by some species.  

 

For various CP genera below, we present the anatomy of carnivory in four steps showing the basic mechanisms involved. 

 

1.  LURE 
   - visual (leaf color/shape)
   - olfactory (fragrance)

   - food (nectar glands)
 

2.  CAPTURE 

    - pitfall trap  (pitcher-shaped leaf)

    - adhesive trap  (adhesive glands - how many times)

    - snap trap  ()

    - suction trap  (glands water expulsion)

    - lobster-pot trap  (glands water flow)

 

3.  DIGESTION

    - digestive glands secrete enzyme - the Golgi apparatus (how many times.../how soon)

    - commensals (bacteria,,,,)

 

4.  ABSORPTION 
    - glands  (cuticular discontinuity)

    - no glands (cuticular discontinuity)

 

GLANDS - The gland plays a significant role in carnivory: Glands are used for lure (nectar gland), digestion (enzyme secretion) and absorption of the digestion products. For adhesive traps, the glands are also used for secretion of viscous mucilage (or resin in the case of Roridula). Generally, adhesive secretion can repeat many times, but can occur only once in Pinguiculas adhesive glands. Depending on the types of traps, different kinds of glands perform different functions, or the same gland assumes multiple tasks.

 

DIGESTION - In pitfall traps, the digestion can start in the preformulated fluids immediately upon prey capture. In other trap types, there is detection/perception of stimuli associated with prey capture, and the digestive process is initiated within a certain time frame. Also, the secretion of the digestive enzyme may repeat several times (as in Dionaea) or can occur only once (as in Pinguicula) depending on the structure of the gland (presence or absence of conducting tissues to the gland). The absorption of the products of digestion is usually carried out by the same digestive glands.     

 

MOVEMENT in CAPTURE - We note that in the course of adaptation to carnivory, there are two distinct points at which a physical movement was acquired, leading to so-called "active" traps in carnivorous plants. One is in the order Caryophyllales in the branch leading to Drosera -- namely the Drosera's tentacle bending (and leaf folding) that eventually led to Aldrovanda and Dionaea snap traps. In the same order, the branch leading to Nepenthes, Drosophyllum and Triphyophyllum did not acquire any such movement. The other is the leaf movement (curling and dishing) in Pinguicula upon prey capture that --- though not as direct or obvious a transition as in Droseraceae --- may have some connection to the workings of some aspect of Utricularia traps... 
 

EVOLUTION CP emerged from non-carnivores at several distinct points in evolution. They only appeared as either a pitfall or adhesive... and only the adhesives moved on to more sophisticated trap mechanisms...

a) CP emerged as pitfalls in:
           Sarracenia
           Cephalotus

b) CP emerged as adhesive traps in:
           Drosera  --- >> Snap traps (Aldrovanda/Dionaea)
                            --- >> Pitfall (Nepenthes) --- >> Adhesive again (Drosophyllum/Triphyophyllum)
           Pinguicula --- >> Suction traps (Genlisea/Utricularia)

 

ANATOMY OF CARNIVORY                                                       LURE / CAPTURE/ DIGESTION / ABSORPTION

 

Poales                 Bromeliaceae                Brocchinia
                                                                      Catopsis

                             Eriocaulaceae                Paepalanthus

 

Oxalidales           Cepalotaceae                Cephlotus 

 

Caryophyllales    Droseraceae                  Drosera

                                                                      Aldrovanda

                                                                      Dionaea

                             Nepenthaceae                Nepenthes

                             Drosophyllaceae            Drosophyllum

                             Dioncophyllaceae          Triphyophyllum

 

Ericales               Roridulaceae                  Roridula

                             Sarraceniaceae             Darlingtonia

                                                                      Heliamphora

                                                                      Sarracenia

 

Lamiales             Plantaginaceae              Philcoxia

                             Linderniaceae                Lindernia

                             Byblidaceae                   Byblis

                             Martyniaceae                  Ibicella

                                                                      Proboscidea

                             Lentibulariaceae            Pinguicula

                                                                      Genlisea

                                                                      Utricularia

 

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