Wednesday, January 6, 2016

Australia 3. The Incredible Carnivores

Carnivorous plants, such as the clump of
Cephalotus at the lower right, often grow
in boggy marshes.
Everyone is fascinated by carnivorous plants.  Earlier, I documented the species found in Florida, but the numbers there pale in comparison with those to be found in Australia. According to the epic 3-volume work on Australian carnivores by Allen Lowrie (1987, 1989,1998), there is one unique pitcher plant, Cephalotus follicularis, three species of Byblis, 19 species of Utricularia, one species of Nepenthes, and the one aquatic species, Aldrovanda vesicularis.   However, the king of carnivores, in Australia and the world as a whole, is the genus Drosera - the sundews.  Lowrie lists just over 100 species, many divided into subspecies. The number of recognized species has increased over the years.  Florabase now lists 110 species for the state of Western Australia alone, which is where the majority of Australian species reside.

Cephalotus follicularis is a pitcher plant endemic to Australia.  It is not related
to the pitcher plants in the genus Nepenthes
One of my goals in Australia was to see as many of the sundews as possible, and maybe even to see Cephalotus growing in the wild.  With only a couple of weeks in Australia in October of 1998, I of course could only skim the surface of this vast assortment of carnivorous plants.  I had to confine myself to the southwestern corner of the country for my primary exploration, but later had an outing in the Snowy Mountains of New South Wales with my friend Heinar Streimann. Sundews were abundant everywhere, however.  Whenever I stopped my car beside the road, I had to step carefully to avoid these prolific, though often tiny plants.
Many species of Australian sundews
produce their trap leaves along upright
The bright orange flowers of Drosera hyperostigma are larger than the rosettes
of trap leaves that produce them.
And I did find Cephalotus!  At the Botanic Gardens in Perth, I asked where I might find them, and they referred me to a nurseryman who was propagating them for the hobbyist trade.  I visited his nursery and saw the baby pitcher plants being groomed for the market.  The owner was at first reluctant to reveal the location of a wild population, but I assured him that the only thing I would take was photographs, and he relented.

Drosera macrantha climbs by using its sticky traps to grab onto supporting shrubs.
After I drove to the location and climbed over a locked gate, it didn't take long to find them.  They were growing in the shallow water of a sedge-filled marsh, forming conspicuous reddish  clumps.  Similar in overall appearance to the tropical pitcher plants of the genus Nepenthes, and less so to our American Sarracenias, Cephalotus is unrelated to either and classified in a family of its own.  The pitchers form as specialized leaves intermixed with ordinary flat leaves, unlike those of Nepenthes, which typically  form at the end of each leaf.

Having satisfied my desire to see the unique pitcher plants, I focused on Drosera, and was soon flabbergasted by the variety of growth forms.  There were the tiny rosettes, which were the most familiar form, but also tall forms with leaves spread out along an upright stem.  Some of these were even vine-like, using their sticky trap leaves to adhere to the branches of shrubs as they climbed.  Later, in the mountains of the east, I would encounter the forking sundew, Drosera binata - a very different sort of beast!

Drosera menziesii is a climbing species with large
pink flowers.
There were all manner of colors in the flowers of the sundews, and sometimes the foliage as well.  I wished that I could have spent more time to document how the  differently colored flowers were pollinated.  I would guess that most were pollinated by small bees or flies, but  have no idea how many different species of pollinators would be involved.

Drosera glanduligera forms colonies of golden yellow rosettes with orange flowers.
I have done my best to identify all the species in my photographs, but some eluded me, and some are no doubt wrong.  As Lowrie himself stated, sundews are very difficult to identify.  So, I welcome corrections from anyone who is knowledgeable of this fascinating group of plants.  Enjoy!
Drosera erythrorhiza has flat, roundish leaves.
Drosera erythrocalyx has bright red leaves.

I have yet to identify this striking sundew, which forms a tangled mesh of red shoots
and an occasional bluish flower. It grows on granite seeps in D'Entrecasteaux National
Park at the southwestern corner of Australia.

Water seeping along this granite slope in D'Entrecasteaux National Park supports
species of  Drosera and Utricularia, along with other specialized shrubs and herbs.

Drosera binata (bottom of picture) grows along a stream in the Snowy Mountains of
New South Wales.

The leaves of Drosera binata split several times.  The ends of
the leaf segments unroll like fern fiddleheads as they grow.
Drosera adelae occurs along Australia's
east coast. The conspicuous sticky drops
at the tips of specialized hairs both
capture and digest insect prey.

References cited:

Lowrie, Allen. 1987, 1989, 1998,  Carnivorous Plants of Australia. Volume 1-3. University of Western Australia Press. Nedlands, Western Australia.