This pattern is called a series out of control (Bryson, 2004, p. 13) or bastard enumeration (Fowler, 1926, p. 22). It belongs to the broader class of failures of parallel structure such as "Mary likes hiking, swimming, and to ride a bicycle.", where the first two items of the list are gerunds but the last is an infinitive (Purdue OWL, 2018). In a series out of control, the parallelism failure is such that literal extrapolation of the list into independent phrases makes one or more of the phrases nonsensical or ungrammatical.
Consider, for example, "Dragons are big, green, and eat people.". We can view this sentence as a compressed form of three sentences:
- Dragons are big.
- Dragons are green.
- Dragons are eat people.
Oops, that last one doesn't quite make sense. The writer meant for the "are" to only apply to "big" and "green", but the syntax connects "are" to "eat people", too. There are lots of ways you could correct this problem. Here are several versions that pass the above test of expansion into separate sentences:
- Dragons are big and green and eat people.
- Dragons are big and green, and they eat people.
- Dragons are big and green. Dragons eat people.
- Dragons are big, are green, and eat people.
(1) is okay but could be a little hard to read. (2) and (3) are more comprehensible. In (2), the comma helps, but it isn't required. (4) is somewhat awkward and would be discouraged by many authorities. This more unusual kind of split, a less blatant kind of faulty parallelism, is attention-getting and most useful for rhetorical or humorous effect, as in "She made no reply, up her mind, and a dash for the door.", from the Flanders and Swann song "Have Some Madeira M'Dear".
Bryson, B. (2004). Bryson's dictionary of troublesome words. New York: Broadway Books. Retrieved from https://penguinrandomhousesecondaryeducation.com/book/?isbn=9780767910439
Fowler, H. W. (1926) A dictionary of modern English usage (1st ed.). Retrieved from https://archive.org/details/dli.ernet.15684
Purdue OWL. (2018). "Parallel Structure // Purdue Writing Lab". Retrieved from http://web.archive.org/web/20181119195059/https://owl.purdue.edu/owl/general_writing/mechanics/parallel_structure.html