From the Aggie Horticulture Goes to Italy student blog:
Saturday was a free day and some of us went to Bologna. While there we
visited the University of Bologna’s garden, the Orto Botanico. It is one
of Europe’s oldest gardens and was established in 1568. Today it has
I had a ton of fun walking around this garden.
There are many trees and little circular planters, each containing a
different species. The most interesting plants were the carnivorous ones
kept in a cage. The fact that they were in a cage made me laugh. There
were a few varieties including the cobra lily (Darlingtonia californica) and the venus fly trap (Dionaea muscipula).
I have not seen carnivorous plants in person so it was fun to look at
these. These plants became carnivorous through evolution to compensate
for nutrient poor soil. Both the cobra lily and venus fly trap can
tolerate fire and actually depend on fires to eliminate competition from
other plants which I think is a useful characteristic. Although the
cobra lily is a hardy plant, its roots are delicate and require a much
colder temperature to survive than part of the plant above the soil.
This is because the plant naturally grows in bogs and stream banks fed
by cold mountain water. I would never have guessed the roots need to be
kept at a cooler temperature than the rest of the plant.
I find most interesting about these carnivorous plants are their
trapping mechanisms. The cobra lily uses lubricating secretions and
downward-pointing hairs to force their prey into their trap. This is
common to all North American pitcher plants but this species also makes
use of false exits. This confuses the insect, exhausting it after many
attempts to escape through the false exit and not having the ability to
climb the slippery walls, it falls into the digestive acids at the
bottom of the plant.
Venus Fly Trap
venus fly trap uses an active steel trap mechanism. The trap is a
section of the plant’s leaf. The inside lobes of the trap have hairs
that must be triggered twice in succession or two different hairs on the
same leaf must be triggered in order for the trap to close. This
redundant triggering mechanism is capable of distinguishing between
living and non-prey stimuli and is a safeguard to conserve energy. But
if non-prey triggers the trap, it will reopen in 24 hours. This
mechanism is not fully understood and I think it’s very interesting that
the plant has a way of determining if the movement is from prey. The
fact that the plant can tell which hairs have been touched within a
certain period of time is remarkable. This closure occurs in about 1/30
second in full sunlight. The speed of closure is dependent on
temperature, cooler temperatures causing slower movement. When open, the
lobes of the trap are convex but when closed it is concave, forming a
cavity. The edges of these lobes are lined with stiff hairs intermeshing
when closed, keeping large prey in the trap. But there are holes in the
mesh allowing small prey to escape because the benefit of digesting the
prey does not outweigh the nutrition gained. Bologna is a wonderful
place to visit and I am glad we stopped by to see the university’s
beautiful garden. -Shannon Murray
"Cobra Lily Plants." Cobra Lily Plants. N.p., n.d. Web. 19 June 2013.
"Darlingtonia californica - the Cobra Lily." Darlingtonia californica, Carnivorous Plants Online. Botanical Society of America, n.d. Web. 19 June 2013.
"Dionaea Muscipula - The Venus Flytrap." Venus Flytrap. Botanical Society of America, n.d. Web. 19 June 2013.