Bamboo and Rattan/Rattan/Course-1 Unit-2
- 1 2.1 General characteristics of rattan species
- 2 Check Your Progress Exercise 1
- 3 Assignment
- 4 Assignment
2.1 General characteristics of rattan species
As mentioned earlier Rattan is not one plant but many. If we are to understand which rattan we are dealing with or talking about we need to be able to differentiate the various Rattan genera and species. We need first to be able to differentiate Rattan from other similar looking plants. It is obvious the various Rattan have some common characteristics that make them ‘Rattan’ – what are these characteristics? (Drs. Haridasan/Renuka)
All Rattans are climbers – they need other plants for support.
- The stems are solid
- Member of the ‘palm’ family
Rattans, hence are climbing palms the stems of which are used to make canes, hence the common name ‘canes’. While they are superficially similar to bamboo, the distinguishing feature is that their stems have a solid core rather than a hollow one. Also, rattans need some sort of a support for growth while bamboos can grow on their own.
The question also arises why we need to understand these technical terms and study these descriptions. The usefulness of rattan depends on various stem characteristics. Depending on the use to which we aim to put our Rattan to we need to look at them for certain useful features. The ‘internodal’ length is an important character for choosing rattan for furniture. The thickness of the stem may also be important in its use for furniture but this may not be as important if we are to use it in matting (????). Of course tensile strength, durability and other such characteristics are equally important. There is available information about the suitability of different rattans for the various specific uses, so we first need to be able to identify the various commercially important rattans.
Check Your Progress Exercise 1
It is obvious that we shall not be able to differentiate the various Rattans if we continue to only use only ‘common’ terms for describing them – we need to use some ‘technical’ terms. Before we go into the details of the various Rattan species and their description let us recollect some of the common terms used to describe various parts of a plant. Let us also define some of the key technical terms used when describing the general characteristics.
We need to define these in simple terms)
Need diagrams of part of stem of rattan showing nodes, internodes,axil The spike in rattan with parts labelled, particularly axillary bud.
(Picture of a flower showing various parts (labeled) and an insect sitting on the anthers)
2.1.1 Growth Habits:
Calamus species are perennials. Stems of most species grow in clusters, called clumps. However, there are a few species with a solitary stem.
The slim stem of the liana like rattan palm - often winding like a rope and armed with thorns or bristles, has nearly a uniform girth about the complete length. The girth of the naked stem varies from species to species; this forms an important criterion for commercial classification or identification.
On an average the stem reaches a length of about 30 meters after ten years of growth. However, the stem length varies from species to species and in seldom cases it gets up to 200 meters long. By itself a rattan plant cannot grow higher – it needs the help of other neighbouring trees. Therefore, in its search for light and support it creeps up on neighbouring plants. In doing so it uses the whips, spines, hairs and bristles on its body.
Without this anchorage and entanglement it would sink by its own weight to the ground. Like the girth & length, the internodal length (an important character from the commercial point of view) also varies from species to species and also within the same species. It also varies with age of the plant: young plants have nodes at short intervals and as age increases, the internodal length increases. Another change that comes with the age of the cane is in the color: young stems are green while, mature stems are cream-yellow.
2.1.3 Leaf sheath:
If the upper portion of the petiole becomes broad and flattened so that it is able to wrap around the stem it is called the leaf sheath. The petiole originates from the nodal portion and extends upwards as the sheath, covering the stem compactly. This is an important part from the taxonomic identification point of view especially in the field. In most species of Calamus, the leaf sheath bears a large swelling at the base of the petiole where it is attached to the stem that is termed as the knee or geniculum. The sheaths encircle the stem along its entire length and only a small apical portion is free. They are often armed with straight or curved, needle like spines. After 3-4 years of age the leaf sheaths fall off, exposing the smooth and green stem.
2.1.4 Climbing organs:
There is a whip-like thorny organ originating from a 'swelling' at the lower portion of the leaf sheath, opposite or subopposite to the leafs direction of emergence. This is known as the flagellum. There are small spines on the lower surface of the flagellum. These stout, recurved spines help the plant in clinging to the trees for support.
2.1.5. Leaves and leaflets:
The leaves are large, about 60-80 cm long. They look feather-like, with many narrow long leaflets on both sides of the rachis (mid axis). The leaves are arranged spirally along the stem and alternate in regular intervals. The leaflets are few or many. Sometimes there is variation in the leaf arrangement plants of the same Calamus species. In some they are arranged regularly, while in others they are grouped or fascicled. The leaflets are reduplicate, mostly linear-lanceolate (and rarely broad-acuminate), with parallel nerves, and bristly margins & surfaces. The linear-lanceolate segments contribute to the dishevelled impression. The leaflets of different species vary in shape, size, venation, costae, bristle distribution, leaf margins, etc.
Calamus species are dioecious, i.e the male and female flowers are borne on separate plants. The inflorescence arises in the axil of a leaf and bears a series of tubular bracts. These bracts are a characteristic feature of the genus Calamus. Usually the male inflorescence is more branched than the female. The time from the emergence of inflorescence to anthesis is 45 to 60 days. The rachillae of the female inflorescence have flowers arranged in pairs, each pair consisting of a female with a sterile male. Hermaphrodite flowers are present in Korthalsia laccifera of Andamans.
The flowers are minute and generally pale-yellow in colour. They are sessile (have no stalk) with three sepals, three petals, six stamens in male flowers, and a trilocular (three chambered) ovary in female flowers. The ovary, from the very young stage itself, is covered with reflexed imbricate (overlapping) scales in vertical rows. The stigmas are large and reflexed (down curved). The pollination is carried out both by, insects, such as bees & wasps, and by wind.
Fruits are somewhat round in shape, and covered with scales. They have a small stalk and a protruding tip. They are big at the centre and tend to become smaller at the top and bottom portions. When the green fruits ripen, the scales take various shades of straw colour or chestnut brown. The scales are hard, closely fitted, shiny, and have a groove in the middle (?). The number of scales at the central larger portion is almost constant for each species (?). The ripening period of fruits varies from 16 to 18 months. Certain clumps and individual stems have been seen to flower almost every year.
Each fruit bears a single seed at maturity. The seed is roughly round in shape and either smooth, grooved or pitted. The seed has an outer fleshy jelly-like layer which in some fruits is edible and has sweetish-sour taste.
2.1.10 Roots and rhizomes:
The root system holds the plant firmly in the ground and absorbs nutrients from the soil. The primary root system is fibrous. It is observed that the roots spread to a width of 1-2 m and to a depth of 50-60 cm. Roots also develop from the base of the stem, and from small rhizomes, in clump forming rattan species. The rhizomatous roots (i.e., roots which develop from the rhizome) spread laterally and give rise to root buds at regular intervals which grow up as new plants. Thus, rhizomatous roots help in multiplication and spreading of the parent plants.
Check Your Progress Exercise 2