INTRODUCTION

The fastest growing trees are the eucalypts, one type of which, found in New Guinea, has been known to add nearly 8 m to its height in 1 year. Even these “sprinters” are eclipsed by giant bamboo, which can grow over 1 metre a day, 30 m in under 3 months.

At the other extreme, a Sitka spruce found at the tree limit in the Arctic had one of the slowest growth rates on record. From measurements of the annual growth rings in the trunk it was estimated to be about 100 years old yet was only 28 cm tall.

The total growth of which some plants are capable in a lifetime is startling. One of the largest giant redwood trees found had a wood volume of more than 1500 m3 and weighed over 1000 tonnes. Since the seed of the giant redwood weighs less than 0.005 g, the weight increase over the lifetime of this specimen was more than 250 billion times. Large trees like these can live for more than 4000 years, illustrating that plants often combine in their bodies tissues of great antiquity with others that are still youthful, producing new leaves, shoots, roots, fruits, and seeds.

CONTROL OF DEVELOPMENT AND GROWTH FORM

In animals, organs develop very early in life and become an integral part of the whole organism without which it cannot function.