species are arranged in an overlapping rosette, forming a
cistern that holds water and detrital material; the flower
grows from the rosette’s center (plates 3- 46– 47). Some
species have a dense covering of hairlike filaments, called
trichomes, on the leaves that help rapidly absorb water and
minerals. Though most bromeliads are epiphytic, there
are many areas where terrestrial bromeliads make up a
significant portion of the ground vegetation. Epiphytic
bromeliads provide a source of moisture for many canopy
dwellers. Tree frogs, mosquitoes, flatworms, snails,
salamanders, and even crabs complete their life cycles in
the tiny aquatic habitats provided by the cuplike interiors
of bromeliads. Some species of small colorful birds called
euphonias (Euphonia spp.; plate 3- 48) use bromeliads as
nest sites.
Orchids are a global family (Orchidaceae) abundantly
represented among Neotropical epiphytes. There are
estimated to be approximately 25,000 to 35,000 orchid
species worldwide. In Costa Rica, approximately 88%
of the orchid species are epiphytes, while the rest are
terrestrial. Many orchids grow as vines, and many have
bulbous stems (called pseudobulbs) that store water.
Indeed, the name orchid comes from the Greek word
meaning “testicle,” a reference to the appearance of the
bulbs. Some orchids have succulent leaves filled with
spongy tissue and covered by a waxy cuticle to reduce
evaporative water loss.
Like virtually all other plants, all orchids depend
on mycorrhizal fungi during some phase of their life
cycles. These fungi grow partly within the orchid root
and facilitate uptake of water and minerals. The fungi
survive by ingesting some of the sugary products
the orchid generates by photosynthesis. Thus, the
association between orchid and fungus is mutualistic:
both species benefit (chapter 10).The Tasty Pineapple
Pineapple (Ananas comosus) is a terrestrial bromeliad
originally from Brazil and Paraguay. It was widely
cultivated by indigenous peoples before Columbus
and the Spanish arrived in the New World, and thus it
spread north into Central America. After its discovery
by Europeans it was soon cultivated in various other
parts of the tropical world. The spiky, sharply spined
leaves protect the plant, whose single flower cluster
grows in the center of the leaf rosette. Wild pineapples
have flowers ranging in color from purple to red and
are normally pollinated by various hummingbird
species. Domestic pineapples must be artificially
propagated, though some pollination by insects can
occur. Most farming families throughout the tropics
have a few pineapples as part of their “dessert” crops.
In addition, pineapples are now grown commercially in
numerous tropical countries throughout the world and
have become one of the region’s leading export crops
(plates 3- 49– 50).Plate 3- 50. Harvested pineapples. Photo by John Kricher.Plate 3- 49. Pineapple crop. Photo by John Kricher.Plate 3- 51. Flowering
orchids are a highlight of
the Neotropical epiphyte
community. Photo by
Beatrix Boscardin.Plate 3- 52. This beautiful flower is
an orchid of the genus Sobralia.
In Spanish it is called flor de un
día, because the flower lasts for
only a single day. Photo by Scott
Shumway.chapter 3 rain forest: the realm of the plants 55