Utricularia intermedia, southern Oregon. July 11, 2011. (Click photo for more)

I was in a local Home Depot store yesterday and noticed a new shipment of Venus flytraps and some other CPs (sundews and Sarracenia). As I was going through VF pots I noticed some unusual VFs among the normal specimens. They were a "Cup Trap" variant. Since I never grew them before, I got one pot. As many of you may know, these plants produce a trap shaped like a cup. That is, the two lobes of a normal trap are fused at the terminal end, making the trap look like a cup. As you can easily guess, the trap does not close very well. This is a genetic error during gene replication... Or, a mutation that may, in time, lead to something unthinkably interesting. Click photo below for more.

  APG III - LIST         APG III - TREE SUMMARY          APG III - REAL TREE        TREE OF PLANTS         TREE OF LIFE

I created a list of all flowering plants "orders" based on APG III (2009) - Angiosperm Phylogeny Group. The APG is an international group of systematists trying to establish a consensus on flowering plants classification - a collaborative effort to construct a family tree of plants utilizing molecular systematics. My main objective here is to put the names of all taxonomic orders on one sheet of paper (8.5 x 11), so that I can hold it in my hand. This is all the orders of green, flowering plants on Earth today! Of course, I did not forget to identify where our carnivorous plants occur. It took me one whole day to put this list together. (Yep, I did not have anything better to do on that day.) The only software I used for this is Microsoft Paint program.

Being a visually oriented human being, I wanted to see this phylogeny in a pictorial form as well. So, first, I made a summary of the tree of flowering plants: Major groupings are clearly shown in this simple tree, such as "monocots" and "eudicots". Note that we do not have "dicots" (having twin cotyledons) anymore because the dicots do not form a "monophyletic" group (consisting of a node and all of its descentents). Therefore the term dicots (dicotyledons) is now deprecated in taxonomic classification.

Now a real tree. Oh boy, this took me two days to construct. I think I did a pretty good job considering the only software I used is MS Paint. Since a tree usually grows upwards, in defiance of Newton's gravity, I started out by flipping (vertically) the first list I created, and then manually added all branches, making sure the logical connections of the original graph are not altered. Initially I wanted to "circle" all major groupings as in the summary tree, but later decided against it to avoid clutter due to unwanted overlaps of circles.
 
Human minds have a very strong cognitive power to interpret patterns (a picture's worth a thousand words). That's why visual presentation is so important and useful over textual information. Looking at the tree I constructed, my brain can more easily recognize patterns and relationships that are less obvious in the list presentation.

Carnivorous plants in the order Poales are rather isolated from the rest, but it is somewhat expected considering they are all very primitive, para-carnivorous plants.

It is readily observed that, within "core eudicots", carnivorous plants are more numerous in the right major branch (leading to "asterids") than the left major branch (leading to "rosids"). In fact, within rosids, Cephalotus (Western Australian pitcher plant) is the only - and lonely - carnivorous plant. The Cephalotus pitcher very much resembles that of some tropical pitcher plants (Nepenthes), but the similarity is purely the result of convergent evolution - acquisition of characters resembling each other in function due to similar environmental conditions, not due to common ancestry.

The branch leading to asterids is teemed with carnivores, starting with the order Caryophylales, and then Ericales, and Lamiales. It appears that it took nature (or the creator) a long time to come up with the idea of bladderwort (and corkscrew) traps - and make them work remarkably the way they do - because it is positioned at the end of the long road. But then, I may be unduly influenced by a particular way the tree graph is visually presented here.

When you are looking at any visualization, you always must be cognizant of the level (or amount) of information present. In the case of this phylogenetic tree I constructed, the length of each branch, for instance, does not have any meaning. Whether a branch comes out on the left or right of the tree is also arbitrary - a mere cosmetic decision.
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If you are interested in printing these list/trees, click the above to enlarge. And then, the best way to make a good hardcopy is to copy the large image and paste it onto your Word document, adjust the picture size, and then print the document. (If you notice a typo or any mistake in these list/chart, please let me know.)

FAMILY TREE -  Pitcher Plants of Americas (family Sarraceniaceae)

Reference:
 Neyland, Ray and Mark Merchant. 2006. Systematic Relationships of Sarraceniaceae Inferred from Nuclear Ribosomal DNA Sequences. Madrono - A West American Journal of Botany, Vol. 53 (3): 223-232.

Carnivorous Plants at a Glance