Cristation is a genetic mutation that can happen in many types of plants and which leads to an interesting formation of the plant’s stem, as it goes from growing in a normal stem shape, to looking like a fan, and eventually like a brain!
Mammillaria spinosissima 'Un Pico Cristata'
Where might I see Cristation?
Cristation can happen theoretically in any vascular plant- that is, a plant with the xylem and phloem vessels (like the veins of the plant). Most plants you’ll know are vascular plants, with the exceptions being things like moss, algae or lichen- in these more simple structures you won’t see cristation. The phenomenon has been directly observed in at least 107 out of 290 plant families, and no taxonomic group (classification of organisms defined by shared characteristics and genetics) of vascular plants has been totally ruled out.
Crested Jumping Cholla - Cylindropuntia fulgida f. cristata
What does Cristation do/ what does it look like?
Cristation is a kind of mutation which affects the top of a stem (the ‘apical’ stem, from ‘apex’). The tips of this stem grow much bigger, and grow outwards, or appear to converge with other stems. It’s like when spaghetti gets stuck together whilst cooking, but even more tightly attached! It grows into an unusually broad, flat shape and has unlimited growth. In this case, that means the part of the stem that is becoming broader will now keep growing indeterminately, and the change is not reversible. It begins in a fan-like shape, then as it grows the broader edge will start to fold over and over, until it is much more densely growing and looks more like a brain. Sometimes it can revert back to normal growth at this point too- also seemingly at random.
Monvillea spegazzinii cristata / Euphorbia mayurnathanii
How/why does Cristation happen?
Cristation is possible because of meristematic cells, one type of plant cell. These cells are like human stem cells in that they are unspecialised and can become different parts of the plant- so they might become a stem, or a leaf. They are also what makes propagation by cutting possible as they can even become roots! When a plant becomes cristated, the activity of meristematic cells changes as they are growing part of the plant because of a change to their cellular DNA. This type of change is called a ‘somatic mutation’, affecting somatic (bodily) tissue. It happens after fertilisation, so is not passed onto the plant’s offspring and cannot be inherited. It is defined as a natural kind of mutation, and there are a few known causes- but sometimes it happens seemingly randomly. The causes of Cristation that we do know about include hormonal imbalance, being eaten by insects, diseases, physical injury to the plant, sudden temperature changes, heavy watering after a drought, a deficiency in zinc or an excess of nitrogen.
Coral Cactus - Euphorbia cristata
Where do ‘cristata’ varieties for sale come from?
Because of its unusual appearance, of course cristata varieties have become desirable as houseplants! They can also be beneficial in crop cultivation as they can have bigger or more numerous yields thanks to the cristation. To meet this demand, growers artificially induce cristation in their plants. This can be done with chemicals or radiation, or by simpler means like altering the plants’ exposure to light. Certain selectively-bred varieties, or plant cultivars, are more likely to be cristated, and are also used in cultivating ‘cristata’ varieties. Once you have a cristated plant, any cuttings taken will also be cristated as they are clones of the original plant, so their DNA shares everything, including the mutations.
