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World of CitrusWorld of CitrusNatsudaidai Sour Orange
University of California, Riverside — Citrus Variety Collection
https://citrusvariety.ucr.edu/crc3235 (opens in a new tab)
Accessed
Tokurou Shimizu et al. · PLOS ONE · 2016-11-30
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0166969 (opens in a new tab)
Open-access DNA-marker study (CC BY 4.0). Apply only to the study accessions and preserve the authors’ stated identity and parentage limits; it does not by itself establish the identity of every catalog tree or clone bearing a matching cultivar name.
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Robert Willard Hodgson · University of California, Division of Agricultural Sciences, Berkeley · 1967
The Natsudaidai profile reports that its original seedling was said to have been found in a Yamaguchi garden toward the end of the 17th century. Hodgson characterizes pummelo involvement as his opinion based on the described characters, and identifies Kawano and Tajima as named commercial derivatives with distinct maturity/acid descriptions. These are historical and author-attributed claims, not accession-level genetic evidence; the exact printed page was not verified.
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SoCal2warm · Tropical Fruit Forum · 2019-04-18
https://www.tropicalfruitforum.com/index.php?msg=349149 (opens in a new tab)
SoCal2warm reports one fruit plucked from a large, heavily loaded tree at the Los Angeles County Arboretum and identifies it as Natsu daidai. He speculates that Amanatsu may be a somewhat sweeter variety of Natsumikan but does not identify this sampled tree or fruit as Amanatsu. No accession, rootstock, or exact collection date is supplied; keep the observed fruit separate from named Amanatsu/Kawano material.
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Masao Iwamasa · HortScience · 1988-08
https://doi.org/10.21273/HORTSCI.23.4.687 (opens in a new tab)
Table 1 (printed pp. 688–689) summarizes 1983 area, production, region, and shipping season. The common Natsudaidai row reports 2,250 ha and 28,900 t, with May–July shipping in southern Honshu, Kyushu, and Shikoku; a separate Kawano Natsudaidai row reports 11,100 ha and 316,400 t, with March–June shipping. These are historical national totals, not individual-fruit measurements or genetic evidence.
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Hagi Museum · 2026
https://hagimuseum.jp/event/260307_natumikan/ (opens in a new tab)
The museum states that economic cultivation of summer orange began in Hagi in 1876 through the efforts of former Hagi domain retainer Obata Takamasa (1817–1906), to help former samurai who had lost stipends. Current exhibition page; it is a retrospective account, not a contemporary 1876 record.
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Hagi City · 2024-08-26
https://www.city.hagi.lg.jp/soshiki/45/518.html (opens in a new tab)
The city account says summer orange arrived around the beginning of the Bunka era and was used as a yuzu substitute; it separately describes Obata Takamasa sowing seed and distributing seedlings to former samurai in Hagi. The page does not specify an exact arrival day.
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Nagato City · 2010-05-18
https://www.city.nagato.yamaguchi.jp/wadaiback/wadai/n1439.html (opens in a new tab)
Nagato City’s page attributes to a local account the arrival of a shore-washed fruit in An’ei (1772–1780) and says Nishimoto Cho planted its seed; it also says the citrus later spread to Hagi. This is an attributed local-origin account, not an independently dated cultivar identification.
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