Plants of the Amazon Rainforest

Plants of the Amazon Rainforest
“Hence, a traveller should be a botanist, for in
all views plants form the chief embellishment.” C. Darwin, HMS Beagle
The Amazon Rainforest biome
2,100,000 sq mi
an estimated 390 billion individual trees divided into 16,000 species
The Amazon is one of the true Tropical Rainforests on earth
The climate maintains a dense and diverse plant cover
red and purple colors: rainforest cover
green: (savannas) shades of green
Geologic forces during the Cenozoic (65.5MY to present) created the forest
Andean uplift created the environmental conditions that promoted plant and animal diversity
The forest has been in existence for at least 55 million years
The Amazon Rainforest contains c80,000 species of flowering
plants out of 422,000 world-wide
…and roughly 30 Million species of Insects
Titanus giganteus
700 species of beetle
discovered on just one tree.
The flora is extremely diverse, with up to 300 species/acre
Socratea exorrhiza
Bertholletia excelsa
Brazil Nut
…But very few individuals per species
This is in contrast to what is found in Northern forests
Zones, or “layers” of the tropical rainforest
Top layer: Emergent trees
Ceiba pentandra
Kapoc
The tallest trees are the emergents, towering as much as 200 feet above the forest
floor with trunks that measure up to 16 feet around. Wimba: Ceiba samauma 55m
Brazilian mahogany Swietenia macrophylla, 70m
Brazil nut, 50m
Lupuna (Kapoc): Ceiba pentandra 55m
Many emergents have Buttress Roots
Ceiba pentandra
Closed layer: the Canopy
The canopy contains most of the life of the forest
Epiphytes
insects (25% of all species)
lianas and vines
canopy trees
Epiphytes: Plants that grow on plants
Orchids
Bromeilads
Ferns
Staghorn fern
Bird’s nest fern
Lianas (woody vines)
Bauhinia (pea family)
Understory
Plants need to be shade tolerant as
only 5% of the available sunlight reaches this layer
Palms are well represented
34 genera (24% endemic), 189 species
Desmoncus mitis
The Amazon contains about 50% of the New World species
Aroids
Caladium bicolor
Alocasia amazonica
Ferns
Hymenophyllum sp
Filmy fern
Microgramma lycopodioides
Adiantum macrophyllum
The forest floor
Plants adapted to low light
fungi
bacteria
The soil depth is often <2”
Roots for an intertwined mat on top of the soil
Saprophytes: Fungi and Bacteria
Termite bacteria
Roots (probably) always are associated with fungi
Mycorrhiza
Nutrients are recycled almost immediately and absorbed by the biomass above
Due to this symbiotic relationship, nutrients are almost 100% recycled
Nutrients (C and N)
Biomass (plants & animals) = 50%
Forest floor and the first 50cm of soil = 40%
Microbial and Fungal activity in Rivers and the Forest floor convert
biomass back into CO2
45% from soil
55% from rivers
5% of the Carbon reaches the ocean.
Adaptations of plants to the Rainforest
Roots
Plants modify their three organs
Stem
Leaves
Roots
Plants of the rainforest have adapted to their epiphytic habit
prop
palms
buttress
Ceiba
clasping
Philodendron
aerial/contractile
figs
absorptive
orchids
Prop Roots
Buttress Roots
Clasping Roots
Phyllodendron
Aerial Roots, strangler figs
Absorptive Roots
Orchids
Adaptations of leaves
Leaf shape
Entire margin, thick and
tough, often waxy
Young leaves reflexed
and red pigmented
Large leaves capture light
Victoria amazonica
Manicaria saccifera
Leaves up to 30 ft long
Alocasia
Leaves form a “tank”
The leaves overlap to form a tank that catches water and detritus. Hairs
at the base of the leaves absorb nutrients.
Also, this genus can transform it’s photosynthetic mechanism to a more
drought-tolerant pathway (C3 -> CAM) during water stress.
Leaf Drip-Tip
Modifications of the Stem
Prickly Stems
Ceiba pentandra
kapoc
Desmoncus orthacanthos
Palm
Climbing stems
Ribbon vine of Bauhinia guianensis
Stolons for vegetative reproduction
Salvinia
Fruit dispersal
Hard Palm fruits are dispersed by large animals
Attalea palm
Agouti
New World monkeys
Astrocaryum palm
Smaller fruits are dispersed by smaller animals
Three-toed sloth
Fig tree
Really large fruits may have evolved when South America had Megafauna
Glyptodon
Megatherum
Couroupita guianensis
Cannonball tree
Theobroma cacao
cacao
Cuvieronius
Some fruits have been especially taken care of by humans!
Next Time!