BLOWING IN THE WIND

Gurjan (Dipterocarpus spp.):  

The mechanism that causes "helicopter seeds" to spin and keep these seeds aloft is almost identical to the aerodynamics that allow certain insects, bats and birds to hover.

Dipterocarp trees are the emergent giants of Asian tropical lowland forest. Only trees of this height can afford to rely on wind dispersal in a rainforest - where there isn’t much air current below the canopy. The mature fruits with wings of some species of Gurjan can extend up to 30cm.

 

Milk weed (Asclepias spp.)

In comparison to the number of flowers, the pods on this plant seem few. However, each pod is full of over 200 seeds! So, in a colony of a 1,00 odd shoots, thousands of seeds will spread into the environment. Milkweed's seed dispersal method is one that utilizes light, fluffy seeds floating on the wind. The seeds have a crown of silky hairs that carry on wind currents like miniature parachutes. Seeds with a tuft of hair are often referred to as ‘comose’ seeds.

 

Pencil Yam (Dioscorea sp.)

These pendulous clusters of seedpods develop rapidly after pollination and at first blend in perfectly with the plant. The three winged pods then turn pink before drying to a straw brown light papery texture. The rounded wings are about 14-16 mm and each pod contains about 6 seeds.

 

White Chuglam (Terminalia bialata)

The butterfly-shaped fruit of the Andaman Ash tree is about 11 cm across with broad, stiff veined wings. It is often easier to identify tree diversity from what we find on the forest floor as apposed to gazing up into the canopy.

 

DRIFTING IN WATER

The Black Mangrove (Rhizophora spp.)

This long smooth radicle (propagule) is an extension to the actual seed. It is both a float and an anchor for a plant that germinates while still attached to its parent. These trees live in the space between land and sea, forming belts of vegetation along the coast that is regularly inundated by tides. The perfectly balanced and buoyant structures maximize the chance for survival of each seedling and enable their journey to distant shores.

 

Sundri (Heritiera littoralis)

The ‘looking glass plant’ is also common along seashores and has devised a hard, thick walled floating seed. The seed is a 5 to 7 cm ovoid with a prominent keeled edge – This fin like structure has a slight curve to it and actually functions like an in-built sail by catching even a gentle gust of wind along the water’s surface.

 

 The elephant creeper (Entada sp.)

An enormous climber with twisted and angled stems that makes it’s way up to and across the rainforest canopy. Its massive woody seedpods grow over a meter long and about 10cm wide!

When the pod splits open, each seed is a glossy chocolate red disk with a 3-5 cm diameter. The attractive, light seeds with a hard waterproof seed coat, float well and are often found washed up on beaches and riverbanks.

 

HITCHHIKING WITH ANIMALS

 Cat’s claw (Martynia diandra)

This little flowering shrub has an ovoid drupe with an inner woody capsule. The woody part splits open at one end into two curved claws, and each capsule will eventually release about 40 seeds. The spiny structure of the capsules allows them to catch on and travel on animal fur.

 

The Achiote (Bixa orellana)

The Annatto or Achiote is a tropical shrub that can grows up to about 20 meters and is

cultivated primarily for the best-known source of the natural pigment annatto from its bright red seeds. The fruits are in clusters of spiky looking red-brown seed pods covered in soft spines.

These bristles can stick to the body of foraging animals and get transported to other parts of the landscape.

 

Wild millet (Echinochloa crus-galli)

This wild grass originating from tropical Asia is commonly known as cockspur grass or barnyard grass. Often used as cattle fodder and the grain of some varieties eaten by humans, it also disperses easily and is considered in weed in some areas.

The coarse stalk of grass has a tufted annual with ovoid spikelets, densely arranged on branches.

The tiny bristly seeds are dispersed by insects, birds and on the feet of larger animals.