Boswellia carteri

Frankincense, anyone?

Frankincense- the very name conjures up a sense of intrigue and adventure as well as a spiritual feeling. I have always been interested in this plant. No one "had" it. Kew in England was reputed to have a plant, but material was hard to come by. The very rarity of the plant put it out of reach of even the most persistant hobbyist. Political instability in its native habitat (Yemen, Somalia and Eritria) made "going there and collecting it" a near impossiblity.

In the early 1990's Arid Lands Greenhouses obtained seed from Somalia and for the first time, plants were offered by mail order. Of course, the supply sold out almost immediately. In a 1993 conversation with the owner, Chuck Hanson, he indicated that only two plants remained which he was retaining for seed. He reported that his plants grew well, but bore no flowers. He graciously offered the plants to us to see if we could get them to grow out and produce seed. We agreed to bring the plants to the Cal State Biology Greenhouse.

Upon arrival at Cal State, the plants were placed in a well lit greenhouse and kept dry, as they were dormant. In fact, they were kept bone dry during the winter, as our heat was off due to boiler death. Repotting waited until the weather warmed up in the late spring as cold wet conditions would probably be fatal, and I didn't want to take the chance of losing the plants.

To encourage maximum growth I tend to plant into large pots, which I did with the frankincense. I used a medium of pure pumice. The thick-as-pencil roots were tangled and brittle. Upon closer inspection, a shoot was seen coming up near the base of one of the plants. It was growing from a root that had broken off, probably during an earlier repotting or just from the growth of other parts of the plant. Many times, the plant will "tell you" many things, one of which is how to propagate it. In this case, I could use root cuttings to produce new plants. You just have to look closely.

Well, with repotting, plenty of root fragments were generated. Where possible, they were placed "right side up." Where orientation was lost, roots were laid on their sides. The medium was also pure pumice. Water was sparingly applied to keep them from drying out.

Back up material was distributed to several institutions. I also decided to try one plant of each clone outside the greenhouse in full sun. During the first winter outside, a low temperature of 30F/-1C was recorded. The leaves didn't even discolor like the Adeniums beside them. As long as they were in full sun, the cold and subsequent wet weather didn't seem to be detrimental. Of course, we still have at least one of each clone in the greenhouse!

The fact that Boswellia grows from root cuttings is at least encouraging for the immediate propagation of the plant. Since root material will produce adventitious shoots, it is hoped that root material can be introduced into tissue culture which will be a significant future project.

We have one plant growing in a large pot in the enclosed atrium of the Science Lab Center against a south-facing wall. Temperatures there are considerably higher due to all the reflected heat and light. Night temperatures may be slightly moderated by radiative heat coming from the building. As the photo shows, the plant is doing well. So far, it has gone through two winters, one of which was the very wet but relatively warm El Niño of 1997-98.

So far, no flowers have been produced. When the plant flowers, be sure that photos will appear here. Now, we may only have to wait for them to "grow up."

Also note (to aid search engines): According to Nora Martinez, who has done extensive work on the Burseraceae, Boswellia carteri, is synonymous with B. sacra . The latter comes from the Dhofar area of Yemen. Superficial comparisons with the material brought from Yemen and our plants confirms her findings. More detailed comparisons will have to wait for the Yemeni material to mature.