With climate change, heat and drought events have become more frequent. A rise in temperature beyond a critical threshold for a period of time sufficient to cause irreversible damage to plant growth and development is defined as high-temperature stress. These events are often accompanied by drought. Water-limited conditions (also referred to as drought) occur when insufficient soil moisture is available to support the average plant growth and production. Plants must alter their morphology to adapt to the stress. However, little is known about the vessel characteristics of plants grown in different natural drought-gradient ecotopes. Ziziphus jujuba var. spinosa, which is distributed in the cities of Yantai, Shijiazhuang, Yinchuan, and Tulufan, was selected for this experiment. The characteristics of vessel elements in the secondary xylem in stems of Z. jujuba var. spinosa were studied using the isolation method. The results indicated that the stems of Z. jujuba var. spinosa contain various types of vessels with adaptive traits and regular patterns. The proportions of the vessel types differed among the natural drought-gradient ecotopes. The observed vessels could be divided into three types according to the number of tails: no tail, one tail, and two tails. From Yantai to Xinjiang, the length, width, and diameter of the annular vessels and spiral vessels decreased as the natural drought gradient increased, and the ply of the ductal wall thickened gradually; the width and diameter of reticulate vessels showed an increasing trend; the length of scalariform vessels also showed an increasing trend, and the diameter first increased and then decreased (Ningxia is the largest, and Xinjiang is the smallest city); the length, width, and diameter of the xylon also increased gradually. These changes in the stricture of the vessel elements, which improved their efficiency for conducting water and inorganic salts, can quickly supplement the water lost in transpiration in a dry environment, thus improving the plants' resistance to the harsh environment and ensuring normal growth.