Foliar roots, also known as epiphyllous (phyllous means leaf) roots, are defined as the roots which develop from leaves. The roots which develop from part of the plant other than the radicle are called adventitious; therefore, follicle roots are classified under adventitious roots. We all are familiar that plant originates from roots or stems, but have you ever thought of a new plant developing from leaves? Foliar roots possess this distinctive capability. The bryophyllum and begonia plants are the most common example possessing such roots.
Formation of Foliar Roots
Some plants have the ability to originate a new plant through leaves. This is possible only because of foliar roots. Formation of foliar roots occurs because the notches present at the margins of the leaves contain adventitious buds/epiphyllous buds. Epiphyllous buds are vegetatively grown small plantlets on the fringes of the leaves. Under favorable conditions, adventitious buds form foliar roots which give rise to new leaves and these then get detached from the leaf surface of the parent plant to form new plants/clones. This process is also known as vegetative propagation and the new plant formed is considered the clone of the parent plant as the genotype and phenotype of the clone plant is exactly similar to the parent plant.
Examples of Foliar roots
Bryophyllum is the most common example of plants having foliar roots. Bryophyllums are vegetative reproductive plants that are found in many parts of tropical and sub-tropical areas. They are notable for growing small plantlets on the fringes of leaves. These grown plantlets are a result of mitosis of the meristematic type tissue which occurs because of the building up of cytokinins on the margin of leaves. These plantlets are adventitious buds that form foliar roots and detach themselves from the parent bryophyllum to form a new plant. The genotypes and phenotypes of the parent plant and the formed plant are similar; therefore, the new plant formed is the clone of the parent bryophyllum.
Most of the begonia plants are tropical or sub-tropical in origin. They help in vegetative propagation through leaves as they contain epiphyllous buds which form foliar roots. These roots originate new plants under favorable conditions. They do best in situations with shade or morning sun/afternoon shade. The new plant formed is termed as clone of the begonia parent plant. Begonia plants do not have a long life span, and live only for 2 to 3 years, even with good care.