Amazing Seed Germination

(A cluster of flowers from a tropical shrub I believe belongs to the Jatropha genus, Florida, January, 2008)

Over the last month and a half I have been propagating some seeds that I collected down in Florida in January. Thanks to a great friend who is a horticulturist and entomologist down there I was introduced to a woody tropical plant named Jatropha multifida. A member of the Euphorbia family found from Mexico down to Brazil, this tropical evergreen shrub has large deeply lobed leaves and blooms terminal clusters of red flowers. At one point we found ourselves in an area where they had been heavily planted and I thought they just looked great with their big textural look and spread of branches. Even though this shrub or small tree is said to bloom mostly during the summer months, there were still plenty of flowers on them in the middle of winter. Some pollinated flowers from months before had already developed into yellow-orange fruit which by this point had fallen to the ground. I picked one up to examine it since the shape and color were so intriguing. The slightly bulbous three-sided fruit was hiding underneath its thin sweet-smelling skin three dark seeds. Erin described how easy they were to propagate from seed. She told me that all I had to do was remove the seeds, soak them for a day, and then sow them shallowly in soil. So I through a few in my pocket and brought them back north with me.

Most people understand that seeds grow into plants, but I realize now that many people don’t understand the specifics of exactly how that happens. In the office I’ve been using these Jatropha seedlings to explain that very process, and I thought a short blog entry might be enjoyable for others to learn from.

So, let’s first revisit the steps. I gathered the seeds once they had been fully formed and dropped by the plant. Different seeds require different methods of being sown so that the seed coat properly breaks and the plant has the best chance of successful germination, but I knew that these were quite easy. I followed Erin’s suggestions, peeled the fruit off the seeds and soaked them for a day. For most seedlings, you want to initially sow them in what we call a soilless mix. This kind of mix is typically made of peat moss, perlite, and perhaps vermiculite. The mix is free draining, yet holds moisture, has a little bit of nutrient value, yet is not overloaded with organics, microbes, and bacteria that the seedling is not quite ready for at this stage. I, however, didn’t have any soilless mix on hand so I opted to take a little risk and sow the seeds in a reliable potting mix I already had in the office.

I placed the soaked seeds on top of moist soil in plastic containers, to retain moisture longer compared to clay pots, and covered the whole thing with plastic wrap to create a mini greenhouse. Then I waited to see what would happen.

Not even a week later I peaked under the plastic wrap to find that the seed coats had been cracked. A tiny growth had emerged out of the seed and right away began to dig down into the soil. This is called the radicle. The radicle is the initial growth out of the seed that will help the future seedling to get nutrients from the soil and establish roots for the plant. In order for the seedling to take and the plant to do well, it has to first have roots to anchor it and provide nutrients in order for stems and leaves to follow.By about two weeks later I pulled the seeds from their plastic pots to see if roots were developing. I was thrilled to see a number of healthy white roots so I transplanted the seedlings into a slightly larger container, the clay pot you see photographed above. I kept them under plastic wrap to keep the humidity levels high and watched them daily to make sure they didn't dry out. What you can see in the photographs above and below is the next step, a growth called the plumule. This is essentially the initial stem of the plant, from where leaves and other stems will emerge over time.

Jump to another two weeks later, now mid-Febraury, and you can see how quickly the plumule has developed into the initial stem of the seedling. Because this plant is considered a dicot, a certain kind of angiosperm, or flowering plant, it produces two leaves right away.
Now the seedling has established roots, stems, and finally leaves, and can photosynthesize and create energy to continue to grow on its own. It becomes less reliant on the energy stored in the seed, because the seed has already done it's part and gotten the process underway. This seedling actually held on to its seed for a long time and I was kind of surprised. When I thought the seed must have finally been empty and couldn't give any more, I was amazed that it was still pushing out new growth in the form of a long stem and many little leaves. Eventually I knew that the plant would become self sufficient enough that the seed would soon fall off the plant.
By the 22nd of February, you can see how the seedling has grown and become a new plant of its own. The seeds themselves had finally fallen off and were just laying on the soil surface. Today, March 2nd, I even found the roots growing out of the bottom of the pot so it is clearly time to repot the seedlings into larger containers. Since Jatropha multifida can grow to be a woody shrub well over 6' tall and wide I'm curious to see how much it will grow during the upcoming spring and summer!