1. The perimorphs produced by these two species are often infertile.
这两个物种所产生的杂种通常是不育的。

2. The perimorph is a result of the secondary branching on the main inflorescence.
次生花序在主要花序上的扩展分枝导致了这个次级花序。

3. The perimorph is a phenomenon of co-adaptation between multiple animal species.
多个动物物种之间的相互作用引起了这种相互适应的现象。