His apparent emphasis on animals rather than plants is a historical accident: his works on botany have been lost, but two books on plants by his pupil Theophrastus have survived.
hɪz ɐpˈæɹənt ˈɛmfəsɪs ˌɔn ˈænɪməlz ɹˈæðɚ ðɐn plˈænts ɪz ɐ hɪstˈɔːɹɪkəl ˈæksɪdənt: hɪz wˈɜːks ˌɔn bˈɑːtəni hɐvbɪn lˈɔst, bˌʌt tˈuː bˈʊks ˌɔn plˈænts baɪ hɪz pjˈuːpəl θiːəfɹˈæstəs hæv sɚvˈaɪvd.