中泥盆世晚期陆生植物的演化已经达到相当高的水平, 我国以云南中泥盆世晚期植物群为代表, 称为Lepidodendropsis arborecense-Minarodendron cathaysiense-Eocladoxylon minutum (LME)组合。当前在云南武定中泥盆世晚期地层(西冲组上部)中发现的植物主要有Lepidodendropsis arborescense, Eocladoxylon minutu, Rhipidophyton acanthum等, 其中, 在R. acanthum的茎干基部密集共生有腹足动物Valvata sp.。根据植物表面无动物咬食痕迹, 以及腹足动物生态特性和演化分析, 当前陆生植物与水生动物共生的原因是植物茎干飘落水体后, 为水生的腹足动物提供了新的栖息场所, 并随水流、风浪载运至异地埋藏。这种水生腹足动物寄栖于水中物体的生活方式很普遍, 是腹足动物迁徙、扩散的一种重要途径。

During late Middle Devonian, the diversity of land vascular plants had reached a fairly high level. In China, the typical flora of this period is represented by the flora in Yunnan, that is named as Lepidodendropsis arborecense-Minarodendron cathaysiense-Eocladoxylon minutum (LME) assemblage. At the locality of Yangliuhe, Wuding, Yunnan, the plants, including Lepidodendropsisi arborescense, Eocladoxylon minututm, Rhipidophyton acanthum, etc., were found from upper part of the Xichong Formation (late Middle Devonian). Among these plants, the 6 symbiosis specimens of plant R. acanthum and gas-tropods Valvata sp. had been found. Based on the absence of animal bits on the surface of stem, the evolution and palaeoe-cological characters of gastropods, the symbiosis of plant and aquatic gastropods is explained as: the stems fall into the fresh water, that provide the new habitat for aquatic and benthic gastropods; after that, these are carried by current and storm to be buried at other places. The life model of aquatic gastropods is very common, and it is also an important way of migration and diffusion of gastropods. This study provides new evidence to show the diversity in the terrestrial ecological system.