Accordingly, in the case where the spontaneous theory was adopted, from the distribution conditions of the Oshima cherry and Edohigan, the Izu Peninsula theory was advocated, stating that it had sprung up in the area around the peninsula.
これを受けて自然交雑説を採る場合、オオシマザクラおよびエドヒガンの分布状況から、伊豆半島付近で発生したとする伊豆半島発生説が唱えられた。