"senryū" translates from japanese as "river willow."
"kiru"(cutting) or the "kireji"(cutting word) is considered essential to traditional haiku.
therefore i picture an ancient conspiracy of asian lumberjacks.

the same formal elements of syllable constraint, short-long-short, and juxtaposition have defined both senryu and haiku... so their difference is in the content: broadly, traditionally: natural vs. human.

but the literal translation of senryu conjures a tree by a river...
do willow's rarely grow by rivers in Japan? was that considered funny or odd at some point?
yet even if anomalous, wouldn't that just mean: there are diverse exceptions to patterns in nature?

aren't humans and all their inconsistencies still encompassed by 'nature'?
isn't what is considered 'outside nature' also encompassed in a more universal sense of the term 'nature'?
nature! nature! nature! and **** i'm a 'wild' human; can i escape my own humanity?
wait, is there a side to choose from? anymore? by necessity? such definitions seem like embryonic ideologies

haiku traditional senryū

traditional tradition,
tradition
of seasonal flouting--

whipped by the river, we laugh
willow switches turn to crowns