Tropical Botany: Admiration and Awe

 

Epiphytic bromeliad (Guzmania sp.).
Savegre Valley, Costa Rica. 

Ecosystems are defined by their plant life. Deserts by their drought resistant plants like cacti, grasslands by, well, their grasses, temperate forests by their deciduous trees and tropical ecosystems by their sheer abundance of plant life.   Tropical forests occupy only 7% of the Earth’s surface but they host about half the world's plant species. 

I find botanizing in the tropics a daunting experience.  There are so many species, even whole families of plants I don’t know. This high diversity is typically coupled with low numbers of any one species, so on an hour’s hike you might see a particular plant only once.

On our recent trip to Costa Rica, led by Epic Nature Tours, we found an abundance of plants in rainforests, cloud forests and the highland scrub called paramo. 

Epiphytic bromeliads.
Savegre Valley, Costa Rica. 

Blushing Bromeliad (Neoregelia carolinae).
The cup of this plant is filled with water and flowers are emerging.
Cartago, Costa Rica. 

Buffy Tuftedcheek (Pseudocolaptes lawrencii)
feeding on a bromeliad.
Quetzal National Park, Costa Rica. 

Bromeliads are common epiphytes in the tropical forests of Central and South America.  The family Bromeliadaceae contains plants as different as Pineapples (Ananas comosus) and Spanish Moss (Tillandsia usneoides). Many of the Bromeliads we saw had a cup-shaped arrangement of leaves.  These cups fill with rainwater and provide homes and breeding sites for animals like frogs, salamanders and mosquitos.  An unusual bird specializes in feeding on bromeliads.  The Buffy Tuftedcheek (Pseudocolaptes lawrencii) is a brown bird with a buffy throat and cheeks.  It moves between bromeliads, probing for small animals that live within the plants.  

Dancing Lady Orchid (Oncidium nebulosum).
Tampanti National Park, Costa Rica. 

We also found epiphytic orchids in the rainforest.  Members of this large family can be found in every habitat except ice caps.  Their greatest diversity is in the tropics with Costa Rica boasting about 1400 species of orchids. 

Monstera tuberculata on the trunk of a tree.
Carara National Park,  Costa Rica. 

Still another epiphyte we encountered was Monstera tuberculata, a close relative of Philodendron.  Members of the genus Philodendron are natives of tropical America and are commonly grown as house plants.  The Monstera tuberculata we saw was a young plant with leaves tightly appressed to the trunk of a large rainforest tree. The plant grows up the trunk of the tree into the canopy, then switches to a hanging vine with large leaves. 

Heliconia bihai. Theses South American and
Caribbean plants grow well throughout the tropics.
Lankster Botanical Garden, Costa Rica. 

Leaf of Heliconia sp.
Carara National Park, Costa Rica.

Heliconias are common understory plants or small trees in the Neotropics.  They produce large, colorful flowers that are pollinated by hummingbirds.  Heliconias have large leaves much like their relatives the bananas (Musa sp.).  

 

Banana Passionflower (Passiflora tripartita).
Canon, Costa Rica. 

A rainforest vine hanging from the canopy caught our attention.  It was a Banana Passionflower (Passiflora tripatita) with bright pink flowers.  This species is native to the Andes of South America but has become established in many tropical and subtropical locations including the highlands of Costa Rica.

 

Blood of Christ (Columnea consanguinea).
Tapanti National  Park, Costa Rica. 
Photo by Diane Coggin.

Detail of Blood of Christ red leaf spots.
Tapanti National Park, Costa Rica.

Green-crowned Brilliant (Heliodoxa jacula)
a pollinator of the Blood of Christ plant. 
Fortuna, Costa Rica. 

Columnea consanguinea is another interesting rainforest plant.  It is a small shrub of the understory.  The leaves of the plant have translucent red spots that give it the common name, Blood of Christ.  Columnea consanguinea grows in the mountains of Central and South America and is pollinated primarily by the Green-crowned Brilliant hummingbird (Heliodoxa jacula).  The flowers of the Blood of Christ plant are yellow and red and rather small.  The red spots on the leaves help direct the pollinating Green-crowned Brilliant to the flowers.  

Poor Man's Umbrella (Gunnera insignis).
Irazu Volcano National Park, Costa Rica. 

The underside of Poor Man's Umbrella leaves.
Irazu Volcano National Park, Costa Rica. 
Photo by Diane Coggin

Hiking through a stand of Poor Man's Umbrella.
Irazu Volcano National Park, Costa Rica. 
Photo by Diane Coggin

The paramo is a unique ecosystem found at high altitudes in Costa Rica and other countries of Central and South America.  It is a tropical scrub and grassland above the tree line where endemic plants abound.  At the lower reaches of the paramo on the Irazu Volcano we found (Gunnera insignis). This genus of ancient plants date back to the Cretaceous Era when Tyrannosaurus rex walked the earth. Gunnera is widespread throughout the southern hemisphere and Central America.  Gunnera insignis has giant leaves, some over 4 feet wide, supported by a stout petiole. This gives it the common name Poor Man’s Umbrella.  

Toad's Herb (Eryngium carlinae).
Irazu Volcano National Park, Costa Rica. 

We found other interesting plants on the Irazu Volcano paramo.  Toad’s Herb (Eryngium carlinae) is a member of the Carrot family (Apiaceae). These plants have a long history of medicinal use and are used to treat diabetes, digestive distress and high blood pressure.  

Costa Rican St. John's Wort (Hypericum iruzuense).
Irazu Volcano National Park, Costa Rica. 

Costa Rican St. John’s Wort (Hypericum irazuense) grows only in the paramo habitat in Costa Rica and western Panama.  With its bright yellow flowers and small opposite leaves, Costa Rican St. John’s Wort stands out among the paramo plants.  

Paintbrush (Castilleja irasuensis)
growing on the paramo.
Irazu Volcano National Park, Costa Rica. 

Castilleja irasuensis, Paintbrush, is an endemic plant with bright red flowers, growing on Irazu. This plant belongs to a large genus of more than 200 species that ranges from North and South America to northern Asia.  A field of these plants looks like brushes that have been dipped and are ready to paint. Castilleja irasuensis grows only on the paramo of high mountains in Costa Rica and Panama.  

Pelican Flower (Aristolochia grandiflora).
Heredia, Costa Rica.

An unopened Pelican Flower
that is supposed to resemble a pelican.
Heredia, Costa Rica. 

My favorite plant from Costa Rica was Aristolochia grandiflora or Pelican Flower.  This tropical vine produces one of the largest flowers in the world. Before the flower opens it is said to resemble a pelican, giving the plant its common name.  The 8-inch, heart-shaped flower is white with purple markings.  Aristolochia grandiflora is pollinated by flies and attracts these insects by releasing a smell like rotting flesh.  Even the color of the flower mimics a decaying animal.  When a fly, attracted to the odor and color, enters the tube of the flower it is forced deep inside by downward pointing hairs.  The fly is then trapped inside the flower where it drinks nectar and collects pollen.  The next day the hairs that had trapped the fly collapse allowing the fly to escape and carry the pollen to another Pelican Flower. 

Alfred Russel Wallace, who along with Charles Darwin, proposed the Theory of Natural Selection.  Wallace was a keen observer of tropical botany.  In his book Natural Selection and Topical Nature, he wrote, “Here no one who has any feeling for the magnificent and sublime can be disappointed… the parasitic plants growing on the trunks and branches, the wonderful variety of foliage, the strange fruits and seeds that lie rotting on the ground – taken together surpass description and produce feelings in the beholder of admiration and awe”.  Admiration and awe indeed.

Costa Rican Hummingbirds

Fiery-throated Hummingbird (Panterpe insignis).
Savegre Valley, Costa Rica. 

Hummingbirds abound in superlatives.  They are the smallest of all birds, they have the highest metabolic rate of any warm-blooded animal and they are counted among the most colorful creatures on the planet.  Hummingbirds are found only in the New World.  There are 366 species of hummingbirds, but the United States has only 15 species.  The diversity is much higher in Central and South America with Ecuador hosting an astonishing 132 species. 

As with many birds, the male hummingbirds typically have much brighter plumage than the females.  The males use their brilliantly colored feathers to attract females and warn off other males from their territories.

The color of hummingbird feathers can change before your eyes.  A male hummingbird with a black throat can turn its head and flash a brilliant red.  These changeable colors are not due to pigments but from the fine internal structure of the feathers.  Structural color is caused by light refraction and usually requires viewing from a particular angle to be seen.  This is why hummingbird color seems to appear then disappear just as quickly. 

The brilliant colors we see on hummingbirds is not how the birds see themselves.  Bird’s visual systems can discern all the colors we can see but they can also detect the ultraviolet part of the spectrum.  Humans have three types of color detecting cells in their retina called cones.  One type of cone is sensitive to red, another cone detects green and a third type is tuned to blue wavelengths.  Birds have these three kinds of cones, but they also have a fourth type of cone that detects ultraviolet radiation.  So, birds, including hummingbirds, experience the brilliant colors produced by their feathers in ways we can only imagine, combining the iridescent structural colors with ultraviolet radiation.  

Lesser Violetear (Colibri cyanotus) in a rainshower.
Savegre Valley, Costa Rica.

On a recent trip to Costa Rica, we saw some of these colorful hummingbirds.  One of our stops was Batsu Garden in the Savegre Valley of the Talamanca Mountains.  This garden is planted with hummingbird friendly flowers and feeders.  Here we found the beautiful Lesser Violetear (Colibri cyanotus). These birds are brilliant green with patches of iridescent purple feathers covering their ears.  Lesser Violetears are found high in the mountains of Central America and the Andes of South America.  

Brown Violetear (Colibri delphinae).
Talamanca Mountains, Costa Rica. 

Brown Violetear showing its iridescent green throat patch.
Talamanca Mountains, Costa Rica.

Brown Violetears (Colibri delphinae) are close relatives of Lesser Violetears but with muted brown feathers over most of their bodies and violet on their ears.  But Brown Violetears have a surprise.  When seen at just the right angle their throat feathers flash brilliant green.  Brown Violetears have a similar range to that of Lesser Violetears.  

Female Green-crowned Brilliant (Heliodoxa jacula).
Talamanca Mountains, Costa Rica. 

Green-crowned Brilliants (Heliodoxa jacula) are also found in the mountains of Costa Rica and range south to Colombia and Ecuador.  We saw a nice female with her throat and breast spangled with sparkling green feathers.  

Crowned Woodnymph (Thalurania colombica).
Guayabo National Monument, Costa Rica. 

On the Caribbean side of the mountains, we visited the Guayabo National Monument.  The monument is a pre-Colombian archaeological site with foundations of buildings, aqueducts, roads and tombs. In the rainforest near the ruins, we found a single Crowned Woodnymph (Thalurania colombica).  These dark hummingbirds are violet and bright green. They live throughout most of Central America and south to Ecuador.  

Talamanca Hummingbird (Eugenes spectabilis)
looking dull.
Savegre Valley, Costa Rica.

Talamanca Hummingbird. The same bird as above
showing bright color on its throat.
Savegre Valley, Costa Rica. 

Talamanca Hummingbirds (Eugenes spectabilis) are restricted to the mountains of Costa Rica and western Panama, and we saw them throughout the highlands.  It is one of the largest hummingbirds in Central America.  Talamanca Hummingbirds have green bodies and their heads and throats appear black. But if the bird turns its head in just the right way the throat flashes blue and the crown of the head purple.  The Talamanca Hummingbird was once classified as a subspecies of the Magnificent Hummingbird.  This species was split in 2017 into Rivoli’s Hummingbird that ranges from Nicaragua to the mountains of southern Arizona, and the Talamanca Hummingbird.  You can truly say the Talamanca Hummingbird was magnificent.   

Fiery-throated Hummingbird showing
relatively subdued colors.
Savegre Valley, Costa Rica. 

Fiery-throated Hummingbird flashing
brilliant, iridescent colors on its throat and crown.
Savegre Valley, Costa Rica. 

Perhaps the most spectacular hummer we encountered was the Fiery-throated Hummingbird (Panterpe insignis).  This green hummingbird looks rather plain until turns its head and looks directly at you.  Then the throat lights up blue, gold, orange and green while the crown of the head flashes purple.  The Fiery-throated Hummingbird is another species restricted to the higher elevations of eastern Costa Rica and western Panama. 

Hummingbirds are tiny avian jewels.  With their stunning speed, superhero senses and brilliant flashes of color, hummingbirds dazzle wherever we encounter them.  At our home in North Carolina, we are lucky to have a single species, the Ruby-throated Hummingbird (Archilochus colubris). But going south to the tropics we experienced some of the stunning diversity of hummingbirds.    

Thanks to Paul, Amanda and Richard Laurent of Epic Nature Tours for planning and leading us on this wonderful trip to see the bird life of Costa Rica.