The long isolation in the different phytogeographical units ( i . e . the northeastern gondwana unit and south china subunit during the early devonian ) and different environment may result in the evolution and diversify of numerous endemics 不同古植物地理区的长期隔离（也就是，早泥盆世的东北冈瓦纳古植物地理区和华南亚区）和独特的环境可能是造成众多地方性分子演化分异的原因。
