Many people confuse roots and rhizomes and don’t know what’s the difference between these two. Although both are the underground part of a plant, they are fundamentally different.
What are rhizomes, and how are they different from the roots? Rhizomes are modified stems that store energy for the plant and can be used for vegetative reproduction. Some rhizomes, such as ginger or turmeric, are used as spices. Unlike rhizomes, roots have a root cap located on the tip of the root, whose role is to protect the soft root tip. Understanding the difference between roots and rhizomes is important for growing sturdy and beautiful rhizomatous plants.
What are Rhizomes?
Rhizomes, also called creeping rootstalk, are stems that grow horizontally. It’s usually underground, but it can also be seen on the soil surface in some species of iris and fern. Unlike true roots, rhizomes have internodes and nodes. They also have a dominant, terminal-growing bud. It can put out both shoots and roots: the bottom side of the rhizome grows roots, whereas the top sends up shoots.
Rhizome plants use rhizomes to store energy through proteins, starches, and glucose, which help the plant survive in unfavorable environmental conditions.
There are two rhizome types:
Dense or Compact
The classification is based on the length of the internode. An internode is a part of the stem between two nodes. Dense rhizomes have short internodes and they form dense and compact clumps that don’t spread. An example of a plant with a compact rhizome is ginger. It stays in a clump and doesn’t spread too fast horizontally.
Running rhizomes have longer internodes, and they spread horizontally. Bamboos have running rhizomes and can spread all over the garden, making them a bit tricky to control.
Rhizomes can also be divided into different categories based on their stem system:
Underground Stem System
The underground type is the most common type of rhizome. Rhizome plants like this type include grass species, ginger, bamboo, rhubarb, and poison oak.
Above-ground Stem System
Rhizomes growing above ground are less common and grow close to the soil. Ferns and some types of irises have above-ground rhizomes.
Multi-layered Stem System
A multi-layered stem system is the rarest type. Both roots and shoots form from the nodes in several layers, and plants with this type of rhizomes are intricate and complex-looking. Unlike other plants with a single layer of roots and shoots, multi-layered rhizomes have different layers of leaves. Giant horsetails are an example of multi-layered rhizomatous plants.
These are some of the most common plants with rhizomes:
However, you should be aware that some weeds and invasive plants also have rhizomes. They are very vigorous growers and they can grow even from a small piece of a rhizome. This means that they spread rapidly and the only way to eradicate them permanently is to remove every piece of a rhizome.
These are the most common weeds and invasive rhizome plants:
- Poison Ivy
- Japanese Knotweed
- Creeping Charlie
- Field Horsetail
Comparison between Rhizomes, Bulbs, Stolons, and Corms
Bulbs, Rhizomes, Stolons, and Corms are different types of modified underground stems. Each of them has unique features which help distinguish them.
This grows horizontally underground, storing energy essential for the plant’s survival in harsh conditions. Rhizomes also help the plant reproduce asexually, via vegetative reproduction. Examples of rhizomes include ginger, turmeric, and bamboo.
Bulbs are underground stems consisting of a center bulb surrounded by scale-like layers. These scales are actually modified leaves that store plant nutrients and are attached to a basal plate. A basal plate is the bottom of the bulb from which roots grow.
Some examples of bulbs include tulips, hyacinths, daffodils, and onions.
Stolons, or runners, are long stems that creep above the soil. The roots can grow at any node along the stem. Stolons aren’t thick and fleshy because their purpose is propagation, and they don’t store energy. The strawberry plant has stolons.
Corms are swollen stem bases that are modified into storage tissue. They consist of layers of tissue, attached to the basal plate. Corms also have a thin tunic and a growing point. If you cut a corm in half, you won’t see the storage rings, which can be seen in bulbs.
Corms store nutrients and produce cormels on top of the old corms. These cormels will produce a new plant, but it takes some time and patience until the plant reaches the flowering size.
These are some examples of corms: gladiolus, crocus, and freesia.
Tubers are a type of swollen stem with growth nodes, from which the new plants grow. Unlike bulbs and corms, tubers don’t have a basal plate or a protective tunic cover. Examples of tubers include caladiums, anemones, oxalis, and potato.
You can propagate plants with rhizomes easily by following these steps:
- Choose a mature and healthy parent plant
- Carefully dig out the rhizome from the parent plant, and make sure that it’s robust and intact. Don’t use rhizomes that are soft, mushy, or smelly.
- Use a sharp sterilized knife and cut the rhizome into sections. Each section should have at least one growth node.
- Before putting the cut rhizome sections in the soil, let them dry for a few days in a warm and dry spot, so they can form calluses over the cuts, which will reduce the chances of rotting.
- Fill the container with a well-draining soil mix. Using a porous potting mix is important to reduce the chances of fungal diseases. You can use a store-bought mix to improve aeration and drainage and add amendments with large particles, such as perlite or vermiculite.
- Put the rhizome sections in the soil ensuring that the growth points are facing upwards. Put a thin layer of soil over the rhizomes and gently press down.
- Water the soil thoroughly.
- The timeframe for sprouting depends on the environment and the species, and it can take from a week to a month for most plants. The exception is ginger which can take anywhere from 3 to 8 weeks to sprout.
- When the plant sprouts, it’s important to put the container in an area with plenty of bright indirect light to encourage optimal growth.
Since rhizomatous plants grow vigorously, some species can overspread and overtake your garden. Luckily, you can prevent them from overspreading by using two simple methods:
- Using a physical barrier.
- Using a spade to sever the excess rhizomes.
You can use a physical barrier to prevent rhizomatous plants from overwhelming your garden. You should put the barrier deep into the soil, and the plants won’t be able to grow past the barrier. For example, you can bury a plastic container so the plant can’t grow past it.
The second option is to spade deeply around your plants to remove and sever any straying rhizomes. It’s best to do this twice a year: once in the spring and the second time in the late summer.
Rhizomatous plants can be a great addition to your garden, especially due to their sturdiness and ability to be easily propagated. With some careful monitoring and planning, you can control their tendency to overspread and they will reward you year after year with their beautiful blooms.
Vladan Nikolic, also known as Mr. Houseplant, is a houseplant care expert with over 12 years of experience in indoor plants and gardening. He is the founder of Mr. Houseplant LLC and a social media influencer with over 500,000 followers on various platforms, including Instagram, TikTok, YouTube, Facebook, LinkedIn, and Twitter. Vladan grew up in Belgrade, Serbia. He spent ten years working in the non-profit sector, but he felt something was missing.
The love for plants was always in his family. His mother and brother always had a lot of houseplants. Vladan’s love for plants started when he began greening up the area around his home and realized how much he enjoyed gardening. He continued to pursue his love for nature by dabbling in organic vegetable gardening and starting a carnivorous plant business.
But Vladan’s life really changed when he won the US Green Card lottery! He made a big, bold decision to move to the United States and start life from scratch. He started working for a non-profit in Washington DC, but he also started building a small jungle inside his office and his new home. He felt the need to share his love for plants with the world, so he started posting houseplant care info on Instagram.
In the meantime, Vladan fell in love and met Jeannette, who helped him take his first steps on Instagram. He spent countless hours learning the intricacies of Instagram and producing social media content, including plant videos. His account slowly started growing, and he became a plant influencer, getting brand deals. Vladan realized he loved producing plant content and sharing his knowledge with others.
Now, Vladan does what he loves and lives in Washington DC, helping others discover a happier life with houseplants. His accounts are followed by over half a million people, and his videos have been seen over 60 million times.