Abstract:Malcolmia scorpioides, Tetracme quadricornis, T. recurvata and Lappula semiglabra are common ephemeral plants in the desert of the northern part of the Xinjiang Uilgur Autonomous Region, China. Their biological characteristics such as seed biology, morphology and developmental rhythm make them adapt to the temperate arid environment.(1) Low daily maximum temperature is necessary for germination. Consequently, the seeds avoid germinating in the hot and dry summer, but germinate in the spring and autumn when there are suitable conditions for plants.(2) There are multiple germination periods during spring and autumn, with only a portion of the seeds from the seed bank germinating each time. Therefore, these plants can survive and propagate after certain catastrophic events, which can occur easily in the desert.(3) The shift from vegetative stage to reproductive stage is apparently affected by temperature. The termination of the individual’s life span depends on the soil moisture contents. This might suggest that the growth of these ephemeral plants would resemble the annuals or winter annuals if the soil moisture condition were appropriate for the growth of these plants in the summer.(4) There are two groups of individuals in one population, namely, spring-germinated plants and autumn germinated plants. They differ from each other in many aspects, such as morphology, biorhythm and reproduction rate.(5) with the active growth of plants, the spatial distributions of roots, assimilative organs and reproductive organs change with the changing environment.