Carnivorous Bromeliads by Gerald Krulik

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PERSONAL BIBLIOGRAPHY REPRODUCTIONS--TWENTYSEVEN

36. Krulik, Gerald, "Carnivorous Bromeliads?", PUP TALK
(Saddleback Valley Bromeliad Society), 13(11) p.4-5, November, 2006.

Here is a controversial subject if I ever saw one. I thought it would be fairly straight-forward to research
this topic. I have seen occasional references to carnivorous bromeliads, and I thought it would be fun to
check them out. What I found, was that maybe there are, and maybe there aren’t, carnivorous
bromeliads. I also found that some typical carnivorous-listed plants may or may not be actually
carnivorous (1). Some typical carnivorous plants don’t secrete digestive enzymes. Some others trap
bugs, but do not digest them. Commensal bugs eat the trapped bugs, poop on the plants, and give
them their fertilizer boost that way! The distinction seems to be getting blurry due to actual biochemical
work that is being done to clarify what is really happening, versus the old ‘look and ponder’ approach.

What makes a carnivorous plant anyway? There are 5 types of carnivorous plants, but only one is
comparable to any bromeliads (2). So let us look at one of the common types, a pitcher plant like
Sarracenia. Pitchers hold water, just like tank-type bromeliads. They have some means of attracting
and trapping insect prey inside, like downward pointing hairs, pitcher covers, waxy smooth walls,
maybe attractive smells, or translucent eye spots or bright flower-like colors or nectar on the sides of
the pitchers to lure bugs inside. The pitchers usually have some chemicals that dissolve the dead,
drowned bugs and liberate their useful chemicals such as nitrogen and phosphorus. However, this is
not an absolute requirement as many of them rely only on bacteria to dissolve their dead insects. They
don't usually seem to have any poisons as such to kill bugs, except one type of Sarracenia which
secretes a poison in the water. Carnivorous plants are found in nutrient poor soils, like bogs or very
sandy areas. Bromeliads, often growing on trees or rocks, would seem to occupy a similar niche with
similar nutritional needs.

So far it seems like many bromeliads could qualify. The tank-type bromeliads have their leaf bases
tightly compacted and deepened to contain water, and do hold much rotting material. Any of us can
testify to that, as spilled bromeliad water has a characteristic foul smell and gritty consistency. They
obviously have substantial bacterial and fungal colonies in the water, breaking down any organic dust
and debris. Various bromeliads have attractive color spots on the leaves. While many bromeliad tanks
are open quite wide, some like various Quesnelias and Aechmaeas are long open tubes just like
some types of pitcher plants. Many bromeliads have smooth glabrous or waxy surfaces to help water
form droplets and flow down into the pitchers. In fact, many bromeliads may have water-absorbing
trichomes on the bottoms of their leaves, and water-repelling trichomes on the tops of their leaves. (3,
4, 5)

Now the counter-argument. I have washed off countless deposits of bromeliad scum from my arms
and hands. I rarely recall seeing any type of insect carcass, certainly not a packed deposit of ants or
flies or moths or termites, like have been quoted in Nepenthes and Sarracenia pitchers. This argues
against any type of attractive scent or nectar being used to attract bugs. The bromeliad pitchers
themselves seem to be designed to hold water, but not to let the plant directly absorb it very easily.
There are no roots, but there can be specialized trichomes, or modified hairs, to help absorb nutrients
and water as needed. Trichomes are a primary cause of the white colors of tree-living Tillandsias, and
often have characteristic and odd shapes. Other trichomes are smaller, sparser, and much less
obvious. This will be maybe a topic for a future article, as there are many types and functions.

Back to Carnivorous Bromeliads. There are about 2700 named species of bromeliads, according to the
most recent book on the subject (6). How many are considered to be carnivorous? At the moment,
exactly THREE species! (or maybe 4, or maybe more?) While many of the rest may superficially seem
to be pitcher-type carnivores, they fail one or more of the tests.

Catopsis berteroniana in habitat, south Florida (7).

This one is Catopsis berteroniana, from Florida and tropical South America. It has white slippery waxy
coatings on the top side of the leaves leading to the tanks, but the wax disappears where the water is
held in the tanks. Most important, the tanks are filled with the remains of terrestrial (ie, not aquatic-type
that could live in the water) insects. This is the only epiphytic carnivorous plant known, and the only
known carnivorous Catopsis.

The other two carnivorous bromeliads hail from the odd region of South America in southern
Venezuela, with the tepui formations, called the Guiana highlands. These are tall, isolated mesas
composed of sandstone rock, in very rainy areas. They rise abruptly from the jungle, so each mesa can
can be very isolated from the others. These are the ground dwelling plants, Brocchinia reducta and
Brocchinia hectioides. B. tatei is in one list too. These plants also have a loose, waxy interior lining. It is
quoted as having a sweet odor from the tank water, which if true is quite different from the normal
bromeliad water stink. In 2005, it was shown to secrete at least one digestive enzyme into the tank
water, qualifying it for full carnivore status.

This is Brocchinia reducta, in habitat (8).

Another Brocchinia reducta, in habitat (9).

Brochinnia hectioides, in cultivation. This photo was hard to come by, as it did not even show up in a
Google image search, and was not in the Wikipedia. I finally got this off a commercial Czech Republic
carnivorous plant seller’s website. Bless you, Internet! Here is a photo of the possible carnivorous
plant, Brochinnia hectioides (10). The frog one is from a source I lost track of.

Brocchinia tatei, possible carnivore, in cultivation in Germany (11). Note the healthy Heliamphora plants
that grow in the same area in South America!

Here are a few last tidbits about Brocchinia. Apparently, they are one of the two basal (ie, most
ancestral) genera of the bromeliads, based on the latest genetic de-coding. The area in which they
grow also contains some very unusual and hard to grow pitcher-type carnivorous plants called
Heliamphora, ten species of which are now known (12). There are some very tiny aquatic carnivorous
plants called Utricularia which have world-wide distribution (12, 13). Some species have become
adapted to live in the tanks of bromeliads, including Brocchinia. And then there is the odd plant,
Paepalanthus bromeliodes, which also lives there. It looks a lot like a bromeliad, unlike the other
members of its genus, and it is a possible carnivore too. But, it is a member of the Eriocaulaceae, a
completely different type of plant.

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