I still have with me the jade plant that I bought for my classroom almost 25 years ago. I had to make a special trip to the garden center to locate one that year as I needed it for a prop in a lesson in AP Biology about photosynthesis.
Why did I need that plant? Well…do you remember anything about photosynthesis? (I mean, why would you unless you like to memorize chemical formulas from your days in the classroom, and then retain them for the rest of your life…) I’m guessing that you haven’t thought about it in a loooong time! I should start out mentioning that plants use their leaves as little factories to capture sun energy and then they transform that energy into a chemical form that can be used by the plant to make everything that it needs to stay alive. On their way to producing sugars (which we can think about as stored energy) the plants take carbon dioxide from the air, water from the ground, and then produce oxygen as a waste product along with the sugar that they need. Whew. Photosynthesis. There are a lot of structures and chemistry involved and it makes brains hurt everywhere when this unit is taught in biology classrooms. As a teacher I tried to use cute animations, labs, demos, activities, and as many props as I could drag into the classroom. Facing a section in the AP Biology curriculum that demanded that the students understand different types of photosynthesis (adaptations that plants have to survive in extreme environments), I needed examples of the different types of plants.
Which brings me back to the jade plant. This plant comes from Africa; southern Africa to be exact, and it is adapted to living in dry conditions. Remember that plants need carbon dioxide to do photosynthesis? The leaves of most plants have little trap doors (called stomata) that open to let air in. If the plant is losing water through these trap doors too quickly they shut. For plants growing in hot, dry conditions, this is a problem as plants need both CO2 and sunlight to do photosynthesis, but opening the stomata in the day dries out the plant. Jade plants solve the problem by only opening these little trap doors in their leaves at night. The jade does some chemical trickery to store the CO2 dissolved in water stored in the leaves where it is safely banked until the sun comes up. Did you notice how thick the leaves of the jade plant were? These plants need thick, waxy leaves with lots of stored water to support their photosynthesis. When the sun comes up the little trap doors are closed, but the CO2 is released from its chemically captured form in the leaf where it is now used for photosynthesis. Sneaky, right? Do your photosynthesis, minimize water loss, and survive in the wasteland: way to go, jade plant!! The whole process is called Crassulacean acid metabolism or CAM photosynthesis. The entire process was worked out in plants that belong to the same group as jades, which is why I needed a jade plant!
Anyway, back to my plant. It got really old and kind of ugly, so I took cuttings off it and gave plants away to people. When the plant that I kept grew into a shape I didn’t like anymore, I took more cuttings and started a whole new generation of plants growing.
So easy to get a new plant. I made four pots with cuttings, gave two away and kept two with me. They grew really well in my indoor garden under the grow lights and then in the summer I put then outside in a shady location, and they really took off then. These cutting are now the grandchildren of my original plant, but also genetically identical to that jade.
Yes, one plant is much larger than the other. I don’t know why, but I suspect that it may have something to do with the slime mold that suddenly appeared in the soil the first summer that the plants went outdoors. Actually, that’s why they went outdoors. No slime molds in the house!!! Mine looked exactly like the slime mold used in the opening credits of The Last of Us if you watched it. Do you see why the plants moved outside?
The jades are 4 years old now and too big to get behind the chicken wire indoor garden. Mateo and Hannah don’t mess with them, so they are growing in the front room. Everything was fine until…
…this picture arrived in my Facebook feed from Nick’s Garden Center, the place where I bought the first plant all those years ago. It’s a blooming jade plant!!! Me want, badly!!!!!
Dying of blooming jade plant envy, I hit the internet looking for ways to get my plants to bloom. Water more, some sites suggested. Hold the water said others. Everyone said to give the plants a high phosphorus fertilizer to encourage blooming. Do it in the late winter, early spring for best results.
Okay, let’s think about this. This plant comes from an arid region. These are CAM plants, so it makes sense that more water helps with photosynthesis and that means that they have all the materials that they need to grow, and they will prosper if they grow because they need to store extra water in their leaves. The plants actually don’t like overly damp soil, so they have been taking action to keep the soil the way that works best for them. These plants have been growing really well… I think that I have been overwatering them.
Yeah, these guys are totally going on a water diet. I gave the plants high phosphorus fertilizer April 1st, and that is the last water that they got. I don’t plan to give them more for at least another month. I also decided to heavily prune the plants as they are so heavy at this point, they struggle to hold their branches up. You can see all the stakes that have gone in over the last year.
I will probably water these plants with fertilizer again May 1st, but it will be a light watering. It is still too soon to move them outside, but by the middle of May the large plant will be back on the front porch doing its jade plant thing.
Remember that I started this plant with cuttings? That is a type of cloning, and this plant, happily growing on my front porch and hiding all of my delivered packages, is the same plant I used that day decades ago to teach about CAM photosynthesis. That lesson, taught so long ago, reverberates today as I try to convince this plant that it should bloom.
I used to tell my students that biology is life.
Yes, it is.
- There are three main types of photosynthesis in plants. C3 is the most common type that is used by the grass in my lawn, my roses, and the ash tree growing in the front yard. All of these plants struggle in the high heat of the summer because they have to keep the stomata in the leaves shut due to the extreme dryness of the air.
- C4 plants overcome this problem with some chemical trickery that lets them move lots of CO2 along in the cells of the leaf without losing too much water and they grow quickly in July. Corn and sugar cane are examples of these plants.
- Cacti are also CAM plants, but they have really gone to extreme measures to control water loss. The plant that we see is the stem (and the stomata are there) while the leaves have adapted into needles that help protect the plant.
- Class is dismissed.
- Oh, I forgot. Pineapple is also a CAM plant. Pina coladas for everyone who read all of this!!!