Abstract: The seeds of Iris ensata, Iris setosa, Iris chrysographes and Iris bulleyana, the four species of Apogon iris are all dormant. The failure in germination of the seeds were studied by embryos in vitro culture, endosperm scarification treatments, seed coat removal and measuring the force need to pierce the structure in the micropylar end with Instron 5848 MicroTester. The results indicated that embryo was not responsible for dormancy and seed coat had something to do with it, while the mechanical resistance acted on embryo which came from endosperm at the micropylar end was the most important limiting factor to germination. We presumed that the endosperm of the four species of iris seeds may contain the germination inhibitors, which affected the stocking percentage significantly.

Key words: iris, Apogon iris, seed dormancy, germination, reason