My first horticultural project for 2015 is to grow a Flamboyant tree from seed. Delonix regia goes by many names—Royal Poinciana or Flamboyant tree in Florida, Gulmohar in Pakistan, or Flamboyán in my native Puerto Rico. Although it hails originally from Madacascar, it has long since been grown through most tropical regions around the world. It is found in the Caribbean islands, India, Nepal, Vietnam, Australia, China, Israel, among many others.
Puerto Ricans, myself included, hold this beautiful ornamental tree close to heart. It blooms in a profuse display of bright red flowers for up to 10 weeks in the summer season. Like many tropical trees, it grows at an incredibly fast rate. It can grow up to 5 feet per year under optimal conditions to a mature height of up to 50 feet. These trees can also be grown as bonsai in zones where they are not hardy.
Delonix regia on the Doddabellapur route in Doddaballapu, India.
Delonix regia featured in a traditional Puerto Rican scene.
We collected Delonix regia seeds on a recent trip to south Florida. When I brought them home to Iowa, I was eager to get them started. Delonix regia seeds have a very tough outer seed coat which must be scarified in order to germinate. After scarification, the seeds are soaked in water to initiate the imbibition process, in which the seed swells as it absorbs water.
From left to right, the first three seeds were scarified using sand paper.
The last two seeds were scarified using a nail clipper. The embryo is visible in the center.
To my surprise, after only a couple of hours of soaking, the seeds began to be enveloped in what appeared to be a frilled mucilage. The seeds scarified with the nail clipper appeared to have more advanced mucilage development than those scarified with the sand paper. They also appeared more swollen. I am amazed at how quickly these seeds have responded to treatment.
Initial appearance of soaked seeds.
Seeds after about 2 hours of soaking in water.
Frilled endospermic mucilage detail.
I have since planted the seeds in trays, about 1/2" beneath the soil surface. The seeds that displayed rapid mucilage development were planted first. the remaining seeds were planted 10 hours later. Germination is estimated to occur within three days.
I will keep you posted!