comprise vs compose
The traditional meaning of comprise is "to include all parts" or "is made up of".
a) The circus comprises lions, elephants, and clowns. (active voice)
b) Lions, elephants, and clowns are comprised by the circus. (passive voice)
But comprise is often incorrectly used in place of constitute or compose.
c) The plant is comprised of leaves, stems, and roots. (passive voice)
(should read: Leaves, stems, and roots are comprised by the plant.)
d) Leaves, stems, and roots comprise the plant. (active voice)
(should read: The plant comprises leaves, stems, and roots.)
Because they support the traditional, narrower definition of the word comprise, grammarians consider c) and d) to be incorrect.
Stylists dislike c) and d) because those uses indicate ignorance of the traditional definition and more importantly, those uses seem inflated. In c) and d), comprise can easily be replaced by the more common verbs compose, consist, and constitute.
e) The plant consists of (or is composed of) leaves, stems, and roots.
d) Leaves, stems, and roots constitute the plant.
Scientists and academics often use comprise and usually use it incorrectly. Why would anyone use comprise in place of the simpler verbs? --see Politics and the English Language and also ask yourself when you last heard your aunt Martha or uncle Louie use comprise.