My first thought was that under the 2/3 merging arrangements this could go into 1387180, which has 仙人掌/cactus. But that's all tied up with the source of サボテン, so it's probably worth keeping this one on its own.

daijr/s, koj

Google N-gram Corpus Counts
╭─ーーーーーーー─┬────────╮
│ 仙人掌　　　　 │ 10,058 │
│ せんにんしょう │     62 │
╰─ーーーーーーー─┴────────╯