Friday, July 6, 2012

Costa Rica

A traditional Costa Rican ox cart.
I continue remembrances of my early travels with an unforgettable summer in Costa Rica as a young graduate student.  I went there in 1970 to participate in the Organization for Tropical Studies field coure in Tropical Ecology. In fact getting there was an adventure itself.  I had agreed to share driving duties with another grad student, who was taking a jeep down to Costa Rica for the OTS program.  We met in Riverside and began the long trek, first over to Texas to pick up the Pan American Highway, then down through the length of Mexico, Guatemala, El Salvador, Honduras, Nicaragua, and finally Costa Rica.  There were armed conflicts in several parts of Central America at that time, and having groups of armed soldiers peering into our car was both scary and reassuring. 

Young people prepare for a dance in
celebration of Guanacaste Day
Costa Rica, on the other hand has been a stable prosperous democracy for a long time.  The people have a strong commitment to their environment and natural areas, and the small country has one of the best system of national parks in the new world.  It is an ideal place for young biologists or any nature lovers to poke around and enjoy the diverse wonders of the tropics.

We met the other students and instructors in San Jose, the pleasant capital city in the highlands.  In the course of the next two months, our motley crew would visit the major habitats of this small but diverse central American country:  the semi-dry tropical forest of Guanacaste, rain forests on the north and south sides of the country, and the mountain cloud forests and heaths of the central Cerro de la Muerte.

It was the dry season in the southwestern Guanacaste Province, so there wasn't much in the way of wildflowers.  We did have fun, however, tracking the local tribe of howler monkeys.
The howler monkeys at the Finca La Pacifica field station
in Guanacaste were engaged in a behavioral 
study of  North American graduate students.
At  Finca La Pacifica , Cydista sp.a vine in the 
Trumpet Vine Family, Bignoniaceae, was blooming.

In shady spots, an unusual sedge,
 Rhynchospora sp., with white bracts blooms. 
 Sedges are normally green and
wind-pollinated, but some forest species
have evolved white bracts to attract insect

At the Las Cruces field station near San Vito, the rain forest yielded diverse plant life, including species of Chamaedorea and Geonoma, .the gingers  Renealmia and Dimerocostus, the palm-like Carludovica, and cycads in the Zamia family
Renealmia, a relative of the old world
gingers, with pollinating butterfly.

Dimerocostus, a relative of ginger in the family Costaceae.
A wild Zamia, or related genus in the forest at Las Cruces.

An unusual species of the palm genus
Chamaedorea, C. arenbergiana with
multicolored, crowded fruits on
 a spike resembling Indian corn.

The Osa Peninsula hosted a spectacular tropical American rain forest, inhabited by tribes of spider and squirrel monkeys, macaws and toucans.  Small understorey palms were abundant and it was here that I had my debut as a tropical biologist.

We had to come up with an individual research project, and I had noticed a population of spiny palms, Bactris guineensis, blooming at the edge of a swamp.  I decided to find out what pollinated them. It turned out that the peak period of flower activity was at dusk.  So I ended up spending a couple of evenings out in the swamp, hoping for three things: to be able to find my way back to the field station, to not be eaten by some ill-tempered jungle creature with sharp claws and teeth, and of course to see the pollinators.

Happily, it all worked out.  I found that the inflorescences of this palm open quickly in the evening, and that the female flowers were already open and receptive to pollen.  The male flowers in rows next to them were still closed tight.  Immediately, clouds of small flies and weevils found their way to the fragrant flowers.  Some evidently had pollen from another plant on their feet or bellies, and pollinated the female flowers as they arrived.  24 hours later, the male flowers on the same inflorescences opened up quickly, and the small insects fed voraciously on the pollen.  The next morning, having depleted their food supply, they moved on to another fragrant inflorescence with receptive femal flowers, fresh pollen stuck to their undersides. The study was published in Principes, the Journal of the Palm Society.

This freshly opened inflorescence of Bactris guineensis is attractive to small flies and weevils, and the tiny female flowers, hidden from us by the large unopened male flowers, are open and receptive to pollen.  The next night the male flowers would open.
In a clearing in the forest at Osa, I also found an interesting club moss, genus Lycopodium, growing in a dense colony and reaching a height of about 4 feet.  Lycopodiums are  surviving members of an ancient line of spore-producing vascular plants. Non-botanical highlights of the Osa rain forest included the surprisingly marked "89" butterfly, and a transparent tree frog.

Lanky Lycopodiums fill a natural clearing in the
rain forest.
The striking "89" butterfly, Diaethria neglecta, brightens
the gloom of the Osa rain forest.

The fascinating transparent Glass Frogs, in the family Centrolenidae,
display their internal organs in the Osa rain forest.
Our final course segment was up in the Cerro de la Muerte, the highest mountains in Costa Rica, where temperatures sometimes fall below freezing at night.  We were introduced here to montane cloud forest, including some areas of heathlike shrubland, and some surprisingly familiar wildflowers.
In the dwarf shrubland of the Cerro de la Muerte, yellow St. John's Wort (Hypericum) and red Indian Paintbrush (Castilleja) species bloom.

Many species of Castilleja, known as Indian Paintbrush,
are found in the western United States

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