The New Neotropical Companion

Washington’s Olympic Peninsula and of coastal Oregon)

and throughout the tropics, abound with epiphytes

of many different kinds. Cloud forests also host an

abundance of air plants. In a lowland tropical rain forest

nearly one- quarter of the plant species are likely to be

epiphytes, though the representation of epiphytes varies

substantially among forests. As forests become drier,

epiphytes decline in both abundance and diversity.

Many different kinds of plants grow epiphytically. In

Central and South America alone there are about 15,500

epiphyte species. Looking at a single tropical tree can

reveal an amazing diversity. Lichens, liverworts, and

mosses, many of them tiny, grow on trunk and branches

and often on leaves (plate 3- 44). Cacti, ferns, and colorful

orchids line branches. Bromeliads, with distinctive

sharply pointed daggerlike leaves, are abundant and

conspicuous on both trunk and branch alike.

Epiphytes attach firmly to a branch and survive by

trapping soil particles blown to the canopy and using the

captured soil as a source of nutrients such as phosphorus,

calcium, and potassium. As epiphytes develop root

systems, they accumulate organic matter, and thus a soil

and organic litter base, termed an epiphyte mat, builds

up on the tree branch, adding weight (plate 3- 45). Just as

most terrestrial plants, most epiphytes have root systems

containing fungi called mycorrhizae (chapter 6), which

greatly aid in the uptake of scarce minerals. (Mycorrhizae

are also of major importance to many trees, especially in

areas with poor soil.) Epiphytes efficiently take up water

and thrive in areas of dense cloud cover and heavy mist.

Though epiphytes are not parasitic in the strictest

sense, they may indirectly harm their host trees through

competition for light, water, and minerals. Epiphytes

get “first crack” at the water dripping down through

the canopy. However, some temperate and tropical

canopy trees develop aerial roots that grow into the soil

mat accumulated by the epiphytes, tapping into that

source of nutrients and water. In such cases the host

tree benefits from the epiphytes’ presence by obtaining

nutrients from its own canopy. The accumulating

weight of epiphytes, however, may become sufficient to

cause limbs to break off, damaging the tree.

Bromeliads (family Bromeliaceae) are abundant in many

Neotropical forests. The most well known bromeliad is

the pineapple. Approximately 3,000 bromeliad species,

distributed among 56 genera, are known. Leaves of many

Plate 3- 42. Climbers often adhere tightly

to the bark of the host tree, as shown in

this photo, taken in Panama. Photo by

John Kricher.

Plate 3- 44. Epiphytes, or air plants, of

various sorts often coat trunks and

branches in tropical forests. Photo by

Beatrix Boscardin

Plate 3- 43. A large- leaved philodendron

(Monstera sp.) grows on the trunk of

this tree in Guatemala. Photo by John

Kricher.

Plate 3- 45. This deciduous tree in Belize

looks fuzzy due to the dense epiphytic

growth covering the major branches.

Photo by John Kricher.

chapter 3 rain forest: the realm of the plants 53