The Yellow River is the key corridor for <i>Tamarix austromongolica</i> to disperse from Asia inlands to east seashores

Plants of the <i>Tamarix</i> L. genus (Tamaricaceae) mainly occur in arid inlands of Asia, but a few species occur in the coastal areas of China, and the Yellow River may account for this. This study was conducted to elucidate whether and how the Yellow River affects the pattern and development of the <i>Tamarix</i> genus, involving two critical species of <i>Tamarix austromongolica</i> Nakai and <i>Tamarix chinensis</i> Lour. With geographical distribution data, relationships of <i>T. austromongolica</i> with the Yellow River and the pertaining watershed were examined using the method of random permutation. The base-diameter structures of <i>T. austromongolica</i> populations were investigated and compared between different riparian lands that suffer discriminative water inundation. The nearest distances from <i>T. austromongolica</i> locations to the Yellow River and the pertaining watershed were significantly lower than the theoretical expectations in the condition of random distribution (<i>p</i> < .05). In many riparian lands along the Yellow River, wild <i>T. austromongolica</i> populations occurred with vigorous juveniles, despite frequent human disturbances. In coastal areas near the present estuary of the river, wild <i>T. austromongolica</i> plants were still found. In <i>T. austromongolica</i> populations near the Yellow River and sea, the rates of juvenile plants were significantly higher than in other populations situated farther from the river or sea. These findings suggest that the Yellow River can facilitate the eastward dispersal of <i>Tamarix</i> plants that reasonably caused the evolution from <i>T. austromongolica</i> to <i>T. chinensis</i> in ancient coasts in the China east.