by Amanda Linke
Many people embraced becoming plant parents during the COVID pandemic, filling their homes with vibrant tropical houseplants. One of the most exciting aspects of plant care is propagation—creating new plants for free! People would trade their propagations with others for new species, expanding their collection of unique plants. Some even began to sell their propagations in bundles, helping others start their plant collections with an assortment of small plants. But what exactly happens when you propagate a houseplant?
Plant propagation is a type of asexual reproduction, meaning the new plant is an identical genetic clone of the parent plant. Plants constantly grow and have abundant stem cells that help them produce new leaves and stems. These stem cells are concentrated in actively growing areas called meristematic tissue. In this tissue, cells undergo cell growth and division, increasing in size and number, which assists a plant in growing wider and taller. Meristematic tissue also has a unique property which helps plants propagate: totipotency.
Totipotency is the ability of a cell to reproduce and develop into any type of plant tissue and eventually form an entirely new organism. This is different from how some animals can regenerate lost body parts. For example, if a lizard loses its tail, the tail cannot grow into a whole new lizard. In plants, however, when you cut a leaf or a vine, that piece can develop into a new plant while the original plant remains intact.
Not all plants have their meristematic tissues in the same locations. For example:
- Pothos plants are fast-growing vines which climb trees in nature. Pothos concentrate their stem cells at the nodes where leaves attach. Roots that form at the node also help the pothos cling to tree bark.
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Images from eGreenPlants (left) and DeshiRongonaUSA (right).
- ZZ plants are hardy and drought-resistant. They store their stem cells in the leaf axil (the angle between the leaf and main stems). ZZ plants also form rhizomes (underground shoots) to store water, just like ginger and turmeric!
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Images from G&J Florist (left) and Planterhoma (right).
- Snake plants are evergreen plants with stiff leaves that grow around underground rosettes. They have meristematic tissue throughout their leaves. Do you notice a difference between the new leaves coming from the cutting and the rosette?
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Images from The Sill (left) and HousePlantHouse (right).
The leaves from the cutting don’t have yellow edges, but the leaves from the rosette do! This is because the yellow coloring, called variegation, is caused by a weak mutation that will disappear if the plant becomes too stressed. Once the mutation goes away, it will never spontaneously come back. These plants may look different but are still genetically identical.
- Fiddle Leaf Fig Trees are ornamental trees with toxic figs that are infamous for being tricky to care for. Like many trees, Fiddle Leaves store their meristematic tissue in the stem. Stem-cutting propagations will work for most trees, such as willows, maples, and magnolias, but success depends on the season!
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Images from The Sill (left) and South Lumina Style (right).
But what actually triggers plant propagation?
Propagation is triggered by wounding the plant. When you cut or scrape it, the plant responds by healing itself. It first forms a callus over the wound to protect against bacteria. The callus forms quickly like a scab but never disappears like a scar. The plant then uses hormones like jasmonic acid to convert nearby cells into meristematic cells. These cells can then grow into new roots, called adventitious roots, which emerge from various plant parts.
The first time I propagated a plant was a coincidence. I accidentally snapped off a vine from my pothos plant while moving the pot and didn’t notice that the vine had fallen into a different pot. Weeks later when I found the vine in the wrong pot I tried to pick it up and was surprised that the vine was stuck in the dirt with new roots! Since then, I have (intentionally) propagated many of my plants and often share cuttings with friends and family.
The first step to plant propagation is understanding where the meristematic tissue is. It’s exciting to see new roots and leaves develop, especially now that you know those are meristematic cells that are hard at work creating a new plant for you! Based on the previous examples, how would you propagate these plants?
Images from This Day Style (left), BricksGardenExchange (top), OurHousePlants (middle), Shoppigment (bottom).
