Halliday & Matthiessen (1999: 86):
So far, our discussion of taxonomic elaboration has focussed on those steps in delicacy that tend to be construed lexically in the lexicogrammar. But in the overall meaning base, lexically construed folk and scientific taxonomies do not start at the highest degree of generality in delicacy; they are ordered in delicacy after those systems that are construed grammatically. For example, while 'plant' is the "unique beginner" of a particular folk taxonomy, there are several steps in the construal of things that are more general than this — steps that are constructed in the grammar, in categories such as 'thing', 'conscious/ non-conscious thing', 'countable/ non-countable thing' and the like.