Definition of Rhizome
A rhizome is a subsurface modification of a plant stem which is capable of producing roots and shoots from underground. Rhizomes are the modified horizontally running stems of a plant which helps in their lateral growth. The rhizomes running laterally gives rise to roots and shoots from its nodes, that is, the upper part of a node gives rise to shoot and the lower part gives rise to roots. The rhizomes have short internodes. Rhizomes are not present in all the plants and are mainly used by the plants for their storage purposes. For example, rhizomes are used for storage of proteins and starch and other nutrients that a plant can use during unfavourable conditions. Rhizomes also help a plant to propagate vegetatively (asexual reproduction), for example, Ginger, Cannas, Lilly of the valley, Hogs, Asparagus etc. In plants such as ferns and water lilies, rhizomes are the only stem and which is present underwater and only the leaves and flowers are visible from above. Rhizomes are usually called as creeping rootstalk or simple rootstalk.
Rhizomes with culinary properties include Ginger, Lotus, Turmeric etc. Stem tubers are also the modified form of rhizomes, used for storage purposes by a pant. Stem tubers are sometimes the modified form of stolon too which is seldom confused with the rhizome. But a stolon is generated from an existing stem and unlike a rhizome, it has long internodes. Although all the rhizome structure thrives underground there are a few plants in which rhizomes are present on the surface, for example, a few ferns and some plants of the Iris species.
Examples of Plants having Rhizomes
We are well introduced with the plant rhizomes than we think we are because many of the rhizome parts like ginger, turmeric etc, is used by us in a day to day life for the culinary purposes. Following is a list of some of the plants having Rhizomes:
Ginger
This is the perennial plant scientifically known as Zingiber officinale. The underground stem of the ginger plant is modified into rhizomes, also called as ginger root or ginger. Ginger is commonly used as a spice and natural medicine for various home remedies.
Uses of Ginger
- In Indian food, ginger holds great importance, for example, flavouring the curry, making them thick and spicy, used in vegetarian and no vegetarian dishes etc.
- Ginger is a natural medicine, often called ayurvedic medicine.
- Ginger is flavoured by some in the tea and coffee.
- In the Caribbean, ginger is used to make ginger beer.
Turmeric
Turmeric plant comes from the same family as ginger, that is, Zingiberaceae. It is a perianal, rhizomatous plant which is produced commercially every year for their rhizomes. The rhizomes are taken off the plant and then boiled before they are dried. The stick-like structure of the rhizome is then ground into a fine yellow powder which is used for cooking chiefly in Indian Subcontinent.
Uses of Turmeric
- Turmeric is used in Asian cuisine, mainly as a colouring agent imparting a yellow colour to the dish. It also gives a slightly bitter flavour to the food.
- Turmeric has significant cosmetic properties as well. It is considered as an antimicrobial/antibacterial which helps in keeping the skin fresh, glowing and is also believed to cure skin problems like ace and eczema.
- Turmeric, due to its yellow colour property, is used to dye clothes like sarees and Buddhist monk robes.
- It is used as an antiseptic to heal wounds.
Lotus
Nelumbo nucifera, also known as Indian lotus or simply lotus, is a flowering water plant. The submerged modified stem of the lotus plant which is invisible from above and is mostly confused with the root of the lotus are its rhizomatic stems. The cultivators of the rhizomes of lotus obtain high yield compared to the lotus flower cultivators.
Uses of Lotus Rhizomes
- The rhizomes of the lotus are eaten in Asian countries, primarily in India, China and Japan.
- Rhizomes of the lotus are cooked in curries, as a vegetable, taken boiled with vinegar, as a salad etc.
- The dried rhizomes of the lotus plant are also used in the preparation of many vegetables.
Bamboo
The root system of the Bamboo plant also consists of rhizomes. Although these rhizomes are not used commercially they help in to thrive the plant mainly. Based on the type of rhizomatic root system the bamboo plant is divided into two, that is, Running Bamboo and clumping Bamboo. The running Bamboo is the type of Bamboo in which Rhizome only grows horizontally in the ground and never emerge out on the surface. Although new buds arise from the internodes of Rhizome, these buds also never grow as a culm and mostly remain dormant except for few. And clumping Bamboo is the type of Bamboo in which the Rhizome starts growing vertically and emerge from the ground and ultimately grows into a culm. Next Rhizome (Newer) grows from the bud on the previous Rhizome(Older) and the process goes on. Clumping Bamboo have Pachymorph rhizomes. This leads to the formation of a clump.
Other than these plants, some more examples of the popular plants consisting of Rhizomes are:
- Pteridophytes (Ferns, Equisetum)
- Banana
- Canna
- Asparagus
- Iris
- Aloe vera (shallow Rhizomes)
Problematic Rhizomes
Although rhizomes are very beneficial for the growth and storage purposes of a plant, their growth can be problematic for the cultivators sometimes. Many plants that come on the list of invasive plants include rhizomes as a part of their root systems. The uncontrolled growth of rhizomes leads to invasive nature of a plant where it damages all the other plants grown in its vicinity. Also, when a plant with vigorous rhizome spread is taken out, a part of the rhizomes, if left, leads to the creation of a whole new plant from itself. The most aggressive plant species that thrive with the help of rhizomes are
- Urtica (Stinging nettle)
- Equisetum hyemale (Horsetails)
- Glechoma hederacea (Creeping Charlie)
- Polygonum cuspidatum (Japanese knotweed)
- Rhus radicans (Poison ivy)
But not all the rhizomatic plants are troublesome, in fact, some rhizomatic plants such as German iris (Iris germanica) and Tropicanna canna lilies (Canna Phasion) are specially grown by the gardeners for their invasive nature in order for them to multiply uncontrollably which is beneficial for commercially as these plants are grown for their flowers for the marketing purposes. And also, some rhizomatic plants fill up the spaces quickly and effortless which is sometimes required in the problematic areas which are otherwise not favourable for normal plants.
