Crassula cotyledonis challenging perception

It is easier to say that the two plants on the left are Crassula cotyledonis than to confirm the same about the one on the right. Or might they be one of the C. nudicaulis subspecies?

This happens more if you are an amateur and know the species but vaguely. There is an uncertainty phenomenon where clarity meets vagueness, more than an uncertainty principle in all human observation. Epistemology irritates the soul.

Your children don’t look the same and do not all resemble the same parent equally, while some may be remarkably like one of the grandparents. When identifying plants, it is convenient if intraspecies differences are minimal, interspecies ones clear and unambiguous. All plant parts convey their specific identities with varying degrees of certainty; some plant parts are hardly helpful at all.

Life presents examples on a scale that is more continuous than discrete, challenging knowledge and sometimes proving experts wrong. Grey areas between categories dish out proverbial grey hairs to all taxonomists, also to those that "normally know".

Still, some amateurs with curiosity will want to know, their investigations and memory sometimes leading them astray, more than in the case of the scientists. Apologies to all those that have been led astray by identifications presented on this amateur Site.

Continual improvement is incremental and more descriptive of human achievement than the elusive objective of perfection. Judgment is used when one does not know the "right" answer and cannot know it for certain, but must make a call. If the right answer can be proven definitively, judgment is not applicable, should not be used.