A stricter definition excludes the red and glaucophyte algae; the group defined in this way could be called Plantae in sensu stricto.
An even stricter definition excludes green algae, leaving only land plants; the group defined in this way could be called Plantae in sensu strictiore.
[4] Conversely, where convenient, some authors derive expressions such as "sensu non strictissimo", meaning "not in the narrowest possible sense".
It normally refers to a sense which is considered invalid and may be used in place of the author designation of a taxon in such a case (for instance, "Tricholoma amethystinum sensu auct."
Given that an author (such as Linnaeus, for example) was the first to supply a definite type specimen and to describe it, it is to be hoped that his description would stand the tests of time and criticism, but even if it does not, then as far as practical the name that he had assigned will apply.
After a species has been established in this manner, specialist taxonomists may work on the subject and make certain types of changes in the light of new information.
It is in this process of species description that the question of the sense arises, because that is where the worker produces and argues their view of the proper circumscription.
Equally, or perhaps even more strongly, the arguments for deciding questions concerning higher taxa such as families or orders, require very difficult circumscription, where changing the sense applied could totally upset an entire scheme of classification, either constructively or disastrously.
In biological taxonomy the usual assumption is that circumscription reflects the shared ancestry perceived as most likely in the light of the currently available information; in geology or legal contexts far wider and more arbitrary ranges of logical circumscription commonly apply, not necessarily formally uniformly.
"This means that the members of the entire family of plants under the name Malvaceae (strictly speaking), over 1000 species, including the closest relatives of cotton and hibiscus, all descend from a shared ancestor, specifically, that they, and no other extant plant taxa, share a notional most recent common ancestor (MRCA).
In this example, we can know from additional sources that we are dealing with the latter case: by adding other groups of plants to the family Malvaceae s.l., including those related to cacao, cola, durian, and jute, the APG circumscription omits some of the criteria by which the new members previously had been excluded.