Haloxylon ammodendron and H. persicum are shrubs that occur in desert regions of western China.The germination unit of these species consists of fruit (urticle) with an attached winged perianth. To determine if the winged perianth influences timing of germination, seeds of H. ammodendron and H. persicum afterripened for various periods of time were incubated at a 12/12 h photoperiod at 15/5℃ for 10 days. The three treatments were seeds and attached winged perianth (control), seeds in the presence of detached winged perianths, and seeds with winged perianths removed. Freshly matured seeds of H. ammodendron (without perianths) germinated to a high percentage, but those with attached perianths germinated to a significantly lower percentage. The effect of the winged perianth on inhibition of germination gradually decreased with increase in storage time. Thus, winged perianths had no inhibitory effect on germination the following spring. Since attached winged perianths inhibited germination of H. ammodendron in autumn but not the following spring, dormancy of fresh seeds seems to be due to chemical inhibitors in the perianth. Apparently, then, the presence of winged perianths keeps seeds of H. ammodendron dormant until conditions are favorable for their germination. As such, the winged perianth may play a role in survival of this species in its harsh desert habitat. Fresh seeds H. persicum with winged perianths removed germinate slowly and to a low percentage. One month storage at room temperature caused an increase in percentage and rate of germination. The attached winged perianth significantly inhibited germination of freshly mature seeds in autumn and also in spring. Germination of seeds of H. persicum with winged perianths attached was strongly inhibited after all periods of storage. Germination also was partly inhibited in the presence of detached winged perianths. Thus, winged perianths inhibit germination of H. persicum seeds via both chemical and mechanical effects.