Saturday, May 19, 2012

Seed dispersal to germinate away from parent plant

Squirting cucumber (Ecballium elaterium)
Most plants have strategies to disperse their seeds which ensures that they germinate away from the parent plant. 

Seed dispersal is important because most plants have little or no mobility and thus would not be able to colonise new areas and habitats. 

Dispersal is also important as it takes seeds away from areas where they would face stiff competition from plants of the same species.

Plants use both internal and external forces to scatter their seeds far and wide. These include gravity, wind, water, explosive forces, and dispersion by animals including humans. Sometimes dispersal can be by more than one means thus a plant might allow a seed to fall onto the ground so that late it would be carried away by water. This often happens when coconuts fall to the ground along the coast and then carried away when the tide rises.

Some species can forcefully discharge their seeds long over large distances. The seed pods of the bear’s breaches (ħannewija) open with such force that they make a sound like a small pistol shot. 

The squirting cucumber, known in Maltese as faqqus il-ħmir, belongs to the cucumber family. During the summer months it forms a green-yellow fruit about the size of a large olive. 

It gets its name from the fact that when ripe the fruit ejects the seeds out together with a stream of thick liquid. When very ripe the slightest touch is enough for the fruit to explode. 

Children sometimes play with these fruit shooting the seeds and liquid at each other or throwing them in the direction of each other to see them explode and hitting each other with the seeds. 

The liquid that forms in the fruit is highly toxic but it has been used medicinally since classic times. It can act as a laxative and is known as a violent purgative. In parts of Cyprus and Turkey the juice is believed to cure cases of sinusitis, hepatitis and earache.

This article was published in The Times on 24.08.11

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