Bamboos – what are they?

Bamboos are grasses. What makes them different from grasses is the ability to branch and form woody culms and rhizomes.
Culms of some tropical bamboos can reach more than 30 metres but even the tallest representative of the temperate bamboos Phyllostachys pubescens can exceed 20 metres
in ideal conditions.
About 2000 species of bamboos are known, mostly occuring in the Southeast Asia and the Tropical and South America. China and Japan are home of the many hardy bamboos which are of the main interest to us.A heart of the bamboo is the rhizome - an underground part in which the plant stores most of its energy. Rhizome system formation determines the growth character of bamboo:

Pachymorph (thick and short) rhizomes are typical for most of the tropical bamboos and mountain species of the genus Fargesia. These bamboos form rather dense clumps of culms and are spreading slowly. We call them clumping bamboos.

Leptomorph (thin and long) rhizomes are typical for the temperate and subtropical bamboos. These bamboos can form groves or thickets in which the individual culms are more or less distanced from each other. They are usually fast spreading. We call them running bamboos.

Root system of bamboos is shallow, reaching only a maximum depth of 30-40cm. It is highly ramified. Roots at the base of a culm serve as an anchor.

Rhizomes contain buds from which the new culms grow. Culms are made of the nodes, internodes and branches. At the time of active growth the culms may increase as much as 30cm per day in our climate. Branches expand from the nodes in a similar way. The number of branches is often characteristic for the genus.

Sheaths are organs that protect young expanding culms and branches. They are deciduous or persistent.

Although bamboo leaves are evergreen, they are constantly renewed. Compared to the thick waxy foliage of some evergreen woody plants bamboo leaves look fragile. They can resist freezing temperatures by the unique mosaic structure of the veins called tesselation. This tesselation which is clearly visible in all hardy bamboos allows for the more intensive circulation of water in the leaf during the periods of frost.

Bamboos rarely flower. A period of 30-40 years between each flowering is not unusual.
During the flowering which may take several years the plant puts all of its energy into making seeds. After finishing of flowering the plant either dies (clumping bamboos), or may recover with a time (running bamboos). Why is it that the bamboos of the same species begin flowering at the same time yet growing many thousands of kilometers afar is a mystery still unexplained.