The spore morphology of Pteris is stable, and the difference between species is distinct , but the features of spore and sporophyte are not related.

凤尾蕨属植物孢子的形态稳定， 种间差异明显， 但孢子形态特征与孢子体的形态特征是不相关的。

youdao

Or try buying yam and telling the seller you want a particular type when it is obvious to her you cannot tell the difference between the species.

BBC: Letter from Africa: Faking your fufu?

In only two species, robins and goldcrests, was there no discernible difference in size between the spleens of those pounced on by cats and those killed in collisions.

ECONOMIST: Survival of the fittest, and oldest