Phyllotaxy is the pattern of arrangement of leaves on the stem or branch. This is usually of three types - alternate, opposite and whorled. (i) In alternate phyllotaxy, a single leaf arises at each node in alternate manner, as in China rose, mustard and sunflower plants. (ii) In opposite type of phyllotaxy, a pair of leaves arise at each node and lie opposite to each other as in Calotropis and guava plants. (iii) If more than two leaves arise at each node and form a whorl, it is called as whorled, as in Alstonia.Opposite superposed is a type of phyllotaxy in which successive pairs of leaves are present just above each other, in such a way that all leaves appears to be present in one plane, overlapping one another. Example of such type of pattern of leaves is Psidium guajava (guava).

Phyllotaxy in Guava

In guava plants, the type of phyllotaxy that occurs is opposite decussate. Let's delve into the details of each type of phyllotaxy and understand why opposite decussate is the characteristic phyllotaxy of guava.

1. Opposite Superimposed Phyllotaxy:
Opposite superimposed phyllotaxy is a type of leaf arrangement where the leaves are arranged in pairs on opposite sides of the stem, and each pair is positioned slightly above the previous one. This pattern creates a spiral-like arrangement along the stem. However, in guava plants, this type of phyllotaxy is not observed.

2. Opposite Decussate Phyllotaxy:
Opposite decussate phyllotaxy is characterized by the arrangement of leaves in pairs, with each pair situated at a right angle to the pair below it. This pattern creates a crisscross or X-shaped arrangement along the stem. Guava plants exhibit this type of phyllotaxy, where pairs of leaves are positioned opposite each other and form a distinct X-shaped pattern.

3. Cyclic Phyllotaxy:
Cyclic phyllotaxy refers to the leaf arrangement where multiple leaves are attached at the same level on the stem, forming a whorl. This type of phyllotaxy is commonly observed in plants like sunflowers. However, guava plants do not exhibit cyclic phyllotaxy.

4. Verticillaster Phyllotaxy:
Verticillaster phyllotaxy is a type of leaf arrangement where the leaves are arranged in whorls, but the whorls are spaced apart along the stem. This pattern is commonly seen in plants from the mint family, such as basil. Guava plants do not display verticillaster phyllotaxy.

Why Opposite Decussate Phyllotaxy in Guava:
The opposite decussate phyllotaxy in guava plants provides several advantages. The arrangement allows for efficient exposure of leaves to sunlight, ensuring maximum photosynthesis. The crisscross pattern of leaves also helps in reducing self-shading, as each leaf is positioned at a right angle to its adjacent leaf. This allows for better light penetration and air circulation, reducing the risk of disease and promoting healthy growth.

The opposite decussate phyllotaxy in guava is an adaptation that optimizes the plant's ability to capture sunlight and carry out essential physiological processes. It contributes to the overall growth, development, and productivity of the guava plant.

Opposite phyllotaxy