Sunday, July 22, 2007

Seeds of the Sea

Tide too high to go out yet?
Raining and have to hide in the shelter on the high shore?
Here's some things you can do on the high shore.

Get everyone to collect seeds and other things they they can find. Give them a time limit or they will take forever. Come back and have a look at what they've found.

Three NAKED facts about plant seeds on the shores

naked fact #1: Shore plant seeds are Real Tough!

The seeds of shore plants often travel a long distance in the sea to find new places to grow.

Let's see some of the special ways they have to survive this long and dangerous journey.

Thoughtful question: Imagine you have to travel miles and miles in the sea. What do you need to survive?
  • Food
  • Water
  • Ability to float
Talk about these features for the seeds that you might find.

A: Seedling of the Avicennia mangrove tree, already starting to grow
B: Fruits of the Rhu tree
C: Fruits of the Sea Almond tree
D: Part of the ball of fruits of the Nipah palm, already starting to grow
E: Seed pod of Derris, a climber of the mangroves
H: Part of the seeds found in the round cannon-ball like fruit of the Xylocarpus tree
I: Part of the ball of fruits of the Seashore pandan
J: I have no idea what it is

naked fact #2: Staying with mama until they are teenagers?

Some mangrove seedlings are already half grown when they fall off the mama tree
F: Rhizophoa
G: Bruguiera gymnorrhiza

Unlike other seeds which don't start to grow until they drop off the mama plant.

On some mangrove trees (Rhyzophora, Bruguiera) fruits start to shoot while still on the tree. They look like 'long beans' on the tree. Others like Avicennia are also growing inside the fruit and quickly sprout once they leave the mama tree.

naked fact #3: Being long has its advantages!

Trees have to breathe. Being tall means the seedling gets above water more rapidly and can breathe sooner as the tide falls.

Common misconception: It is not true that the long pointed seedlings fall off the mama tree and stab into the mud to grow. It's not good to grow in the shade of mama, for both mama and baby trees.

Ideally, the seedlings would drop off at high tide and float away lying horizontally. With time, the tip gets water logged and starts to dip downwards. Eventually, when they arrive at a good spot, roots grow from the tip and right the seedling in a vertical position. Leaves then sprout from the top.

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