Dr. Judy Rose

Incompatibility in Jasminum

Dr. Judy Rose is a retired research scientist. She is trying to establish a national collection of Jasmine with both pin and thrum plants of as many species as possible. Particularly keen to find thrum plants of J. azoricum, J. mesnyi, J. nudiflorum and would be interested to hear from anyone willing to exchange cuttings or seeds of Jasminum species.

Dr Judy Rose (UK)
email: judy.rose@care4free.net

"...Most Jasmine plants are self-incompatible, the pollen cannot fertilise the ovules. The incompatibility in Jasminum is similar to that in Primula, which is known to many people. The plants come in two morphs or forms. In one in form, the style is longer than the stamens, these are called "pin" or long-styled flowers. In Primula, the style and stigma (the receptive surface on the end) looks just like a pin. In Jasminum the shape of the stigma varies with the species and often does not look much like a pin. In the other form, the stamens are situated at the mouth of the corolla tube above the style, these are called "thrum" or short-styled flowers. Thrum is an old weaving term meaning that the threads pass over the top. In order to get seed set the pollen from a pin plant must fertilise the ovule of a thrum plant or vice versa. Below are pictures of a section of both a pin and a thrum flower of J. beesianum with the flower parts named for those not familiar with them..."