Annette Klausegger, age 12, of Libertyville, Illinois, for her question:

Which is the fastest growing plant?

Those of us who do the weekly mowing suspect that the world's fastest growing plant is the green grass that grows on the lawn. Actually, it grows only a few inches a week. However, some researchers claim that the fastest growing plant is a member of the grass family. It is a certain bamboo that grows in Ceylon. This stiff, stately plant may reach a height of 120 feet. And under favorable conditions it can add 16 inches of new growth during a single day.

Many other fast growers live in moist, tropical jungles where vines add yards of tangles during a week or so. But some researchers suspect that some of the alga type seaweeds grow even faster than any of the land dwelling plants. For example, skimpy colonies of single celled algae can add tons of new growth in a few days. And possibly the kelp seaweeds, with wide 60 foot long ribbons, grow even faster than the bamboos. After cutting, they are ready to harvest again in just a few weeks.