Z1 Tea Cultivar: The Unnamed Line Behind Saeakari and Seimei

by Christian, founder of One with Tea

Z1 is a Japanese tea plant that never got a name. It's a breeding-line code, selected from Tamamidori seedlings at Japan's National Tea Research Station, and it never entered the Cha Norin register. Yet it is the mother of Fuushun (Cha Norin No. 41) and Saeakari (No. 55), a parent of Meiryoku (No. 35), and the grandmother of Seimei, which NARO bred for matcha and powdered tea.

The trade remembers Z1 as a phantom that faded out of trials. NARO's breeding records call it vigorous and resistant to gray blight, and its breeders chose it as a mother in 1965 and again in 1989. Our guide to Japanese tea cultivars maps the wider family.

Key Takeaways

• Z1 (also Z-1 and Ｚ１) is a breeding-line code, not a cultivar name.
• NARO traces it to Tamamidori seedlings and an unknown pollen parent.
• No source gives its selection year; the first documented date is 1965.
• Breeders valued its vigor and gray blight resistance; the trade calls it hard to grow, and Senchado says it is picky about soil.
• Its grandchild Seimei was bred for sencha, kabusecha, matcha and powdered tea. The records don't support Z1 being Yamatomidori.

What is the Z1 tea cultivar?

Z1 is a Japanese tea breeding line that was never registered as a named cultivar, so it still goes by its trial code. In the Cha Norin registered cultivar list hosted by Minorien, Ｚ１ appears exactly twice, both times as a parent (of Meiryoku and Fuushun), never as a row of its own; the list ends in 2004, before Saeakari was registered in 2011. Senchado Tokyo (煎茶堂東京), a tea shop, lists it as unregistered under both MAFF's Norin system and the Seed and Seedling Act.

So "Z1 tea cultivar" is loose language, and I use it because that's how people search. Shinkoju's page address and the Shoutou tea school both read the code ゼットワン, zetto wan.

Z1 at a glance

Attribute	Detail
Written forms	Z1, Z-1 (1992 paper), Ｚ１ (register); read ゼットワン
Status	Breeding-line code; never registered
Origin	Tamamidori seedling; pollen parent unknown (natural cross)
Bred at	National Tea Research Station (国立茶業試験場), per NARO; its children Meiryoku and Fuushun were bred at Kanaya, Shizuoka
Earliest documented use	Seed parent of the 1965 Fuushun cross
Known descendants	Meiryoku, Fuushun, Saeakari; grandchild Seimei
Selection year, planted area	Not in anything I read

Where Z1 came from: a Tamamidori seedling at Kanaya

Z1 was selected from seedlings of Tamamidori, an Uji-line cultivar, and three breeders' documents agree. The 1992 Fuushun paper says so (宇治系品種の'たまみどり'の実生から選抜), and so does the 2012 Saeakari paper. NARO's 2022 handbook draws Tamamidori as mother and a question mark as father, notes 自然交雑, natural cross, and labels Z1 国立茶業試験場育成, bred at the National Tea Research Station.

My Japanese Green Tea (MJGT), Ricardo Caicedo's English reference site, calls Z1 "the result of tea plants from the Tamamidori cultivar that were allowed to breed naturally".

Tamamidori itself is Cha Norin No. 4, registered in 1953, former line 国茶U17, from Uji native seedlings, bred at Kanaya for tamaryokucha (玉緑茶). The register gives Kanaya (金谷) as the breeding place of Meiryoku and Fuushun too, and the 1992 paper's authors wrote from Kanaya town, Haibara District, Shizuoka.

The date nobody wrote down. No source I read gives the year Z1 was selected. The documented floor is 1965, when it was already the seed parent of the Fuushun cross. The trade's estimates: Ito Naoya, a Japanese tea instructor, wrote in 2018 that it was developed over 60 years ago at a Shizuoka tea research station; Senchado (2019) says it was trial-grown at the national station 40 years ago. Those don't line up, so I hold on to 1965.

And the "Z"? None of my sources explains the letter, so I won't guess.

Why Z1 has a number instead of a name

Z1 kept its trial code because it never became a registered cultivar, and none of the NARO papers I read says why. The trade's answer, from MJGT in 2017 and Senchado in 2019, is that it was too hard to grow, and Shoutou (2020) also calls it very difficult to grow.

In Senchado's 2019 account, Z1 was trial-grown at the National Tea Research Station but chose its soil and was hard to raise, so it faded away, a 幻の品種 or phantom cultivar. It suited so few sites that registration as a recommended cultivar (奨励品種) was passed over, and it kept its trial number because, Senchado says, only recommended cultivars were allowed names.

MJGT (2017): "It failed the process for the registration because it is difficult to grow. That's why it didn't get a name except for the serial number used during the tests." Nihoncha Kyoshitsu Shoutou (日本茶教室 松濤, 2020), a tea school in Kanagawa, calls it very difficult to grow and very rare, its name simply the number the tea research station assigned.

These are the trade's accounts, and I couldn't find Senchado's naming rule in any NARO text.

Vigorous on paper, difficult in the field

The people who bred with Z1 describe a strong plant. NARO's 2009 research result, its Saeakari cultivar record, its 2010 press release and a 2019 MAFF page all name Z1's vigor (樹勢が強い), and three of the four its resistance to gray blight (輪斑病).

The press release goes furthest: 樹勢が強く多収で、かつ輪斑病に強い, strong vigor, high-yielding and strong against gray blight. The 2012 Saeakari paper adds moderate anthracnose resistance (炭疽病中度抵抗性), citing Ikeda and Amma (2004). MJGT agrees: "good vigor and yield, and it's also strong against the gray blight".

So which is it? Probably both. My own reading, and it's only mine: vigor in a breeding plot and reliability across many farms are different tests. A plant can grow strongly where it's content and still refuse most ground. The NARO texts I read don't mention soil trouble for Z1 either way, and one small irony stands out: NARO's handbook rates Z1's daughter Fuushun highly in cool areas and on poor soils.

Z1's family: Meiryoku, Fuushun and Saeakari

Z1 has three children in the records I read. It is the seed parent of Fuushun (crossed 1965, Cha Norin No. 41) and Saeakari (crossed 1989, Cha Norin No. 55), and the pollen parent of Meiryoku (Cha Norin No. 35, registered 1986).

Z1's children and grandchild

Cultivar	Cross	Year crossed	Registration	Bred for
Meiryoku	Yabukita × Z1	Not in my sources	Cha Norin No. 35, 1986	Sencha
Fuushun	Z1 × Kanayamidori	1965	Cha Norin No. 41, 1991	Sencha
Saeakari	Z1 × Saemidori	1989	Cha Norin No. 55, 2011	Green tea; suits kabusecha, gyokuro, tencha
Seimei (grandchild)	Fuushun × Saemidori	1992	PVP No. 27874, 2020	Sencha, kabusecha, matcha, powdered tea

Meiryoku, former line Kanaya No. 6, was bred at Kanaya; our Meiryoku guide tells its story.

Fuushun (ふうしゅん, 富春) is where Z1's paper trail starts. The 1992 paper, which spells it Fushun, says Z-1 was crossed as mother with Kanayamidori in 1965. Kanayamidori itself came from a cross of S-6, a Shizuoka native selection, with Yabukita. Seed was harvested the next autumn and sown at once: 172 seedlings. Selection kept 10 by 1971 and two in 1973. After nursery tests on cuttings the line became F1-NN-71, then Kanaya No. 12 in 1983. Trials ran from 1984 to 1990, and it was registered as Cha Norin No. 41 in May 1991. NARO's handbook adds a variety registration, No. 3697 (general variety), in October 1993. By the paper's count, cross to registration took 26 years and 11 people.

Its English synopsis promises "hardy growth, high yield, and distinctive aroma" for "the cool zone of semi-mountainous region of mainland Japan". NARO's handbook describes an upright bush more vigorous than Yabukita, with first- and second-flush yields 30-50% higher, plucking 1-3 days later, and medium or better resistance to gray blight and bacterial shoot blight. It is weak to anthracnose and white peach scale, and its leaf tends dark, so deeper steaming helps. The name 富春 honors the satisfying flavor of new spring, and a wish that its yields would enrich the tea industry.

Saeakari (さえあかり) is the second cross with Z1 as mother, made in 1989 and bred at Makurazaki, with Saemidori (Yabukita × Asatsuyu) as pollen parent. NARO's 2010 press release explains the aim: Yabukita was grown in about 75% of Japan's tea-producing areas and was susceptible to anthracnose and gray blight. The 2012 paper says Saeakari was chosen from 61 plants and trialed as Makurazaki No. 30. It was filed for plant variety protection on 8 April 2010 (No. 24796), recognized as Cha Norin No. 55 on 28 March 2011, and registered as No. 22070 on 14 November 2012. The paper counts 21 years from cross to registration.

Inoculation tests rated it somewhat strong against anthracnose and strong against gray blight, and field anthracnose stayed very low even next to Sayamakaori. It's plucked 3-4 days before Yabukita and out-yields Yabukita and Saemidori in every flush. MAFF adds bacterial shoot blight resistance and suitability for organic cultivation; the handbook says it suits kabusecha, gyokuro and tencha. The name points to the clear, bright leaf and liquor color inherited from Saemidori, and to quality that holds up under bright summer sun.

One line in the 2012 paper is the nearest thing to a portrait of Z1 I found: Saeakari's mature leaf looks intermediate between Z1's and Saemidori's.

The matcha connection: Seimei, Z1's grandchild

Seimei is Z1's grandchild through Fuushun. It was selected from a 1992 cross of Fuushun and Saemidori, bred at NARO in Makurazaki, released in 2017, and written up in 2018 as "New Green Tea Cultivar 'Seimei' for Sencha, Kabuse-cha, Matcha and Powdered tea". Saemidori is also Saeakari's pollen parent.

The Seimei paper calls it "suitable for covering cultivation for tea processing of Kabuse-cha, Matcha and powdered tea" and says "The color shade and taste of powdered tea and Matcha of 'Seimei' is superior to those of 'Yabukita'." At Makurazaki it was plucked four days before Yabukita and yielded consistently more than Yabukita and Saemidori.

NARO's handbook says Seimei suits tencha and moga-cha, the raw material for matcha and powdered tea, which it describes as in surging demand at home and abroad (近年国内外で需要が急増している). Its application, No. 31289, was published on 30 January 2017, which the paper counts as 25 years and 13 researchers after the cross. Registration, No. 27874, followed on 30 March 2020. The name 清茗 means pure tea, 茗 being the tea plant.

Our guide to tencha covers the leaf that becomes matcha, and in the Yabukita problem we covered how little Seimei is planted so far. Breeding is slow, and each paper counts its own road:

Is Z1 the same as Yamatomidori?

No, the breeding records do not support Z1 being Yamatomidori. Yamatomidori is Cha Norin No. 10, former line Nara No. 59, registered in 1953, from Nara native seedlings, bred in Nara for sencha. NARO's documents describe Z1 as a Tamamidori seedling bred at the National Tea Research Station, and the register's rows for its children and the 1992 paper both point to Kanaya.

Our Meiryoku guide noted that some sources online identify Z1 as Yamatomidori, and left it open. Different mother line, different breeding place. Shinkoju (心向樹), a cultivar-tea shop in Saitama, also lists やまとみどり and Z 1 as separate teas in its menu.

Where the idea comes from, I can only guess, and this is my reading rather than anything a source states. The two names sound alike, and both end in midori, green. Akiyamaen (秋山園), which sells single-cultivar teas, describes Meiryoku's father on its cultivar page as a selection from Yamatomidori seedlings (「やまとみどり」の実生群からの選抜). NARO's breeders say that same father, Z1, came from Tamamidori seedlings. One swapped name would be enough to start the rumor.

What does Z1 tea taste like?

Nobody at One with Tea has tasted Z1, so every note here belongs to its source. The five accounts of Z1 tea I found, from 2017 to 2020, mostly lean toward sweetness and a clean finish, but they disagree about bitterness.

Four of the five lead back to Wazuka, Kyoto. Senchado (2019) offered a single-origin "008 Z1" grown there by Tamura Katsumi at 210 m, light-steamed (asamushi), from the 2017 harvest. It says he is the only person growing Z1 in Kyoto, and that he started farming by clearing a bare mountain. MJGT tasted a Wazuka Z1 by Mr. Tamura at Rishouen in Uji, and Ito was told a Mr. Tamura is Kyoto's only Z1 grower. A Mr. Tamura in Wazuka is named in all three.

I found no planted-area figure, and no chemistry or caffeine data for Z1 itself. MJGT calls it "quite rare" and "difficult to find even inside Japan".

Z1 tasting notes, side by side

Source	Year	What they said
MJGT, Rishouen sample	2017	Small, dark, shiny leaves; slightly sweet aroma; wet leaf "perhaps a bit floral", not the pronounced marine fragrance of most Japanese cultivars; clear yellow liquor with some green; good umami, slight sweetness in the aftertaste, clean and fresh; "It isn't bitter at all."
MJGT, cultivar page	2017	"A characteristic smell and a slight sweetness"; some pages call the aroma floral, others fruity
Ito Naoya	2018	Clean mouthfeel, no harsh astringency, a sweetness that spreads slowly
Senchado Tokyo	2019	Uji tea's characteristic aroma with the strength of sencha; stars: sweetness 2, bitterness 3, umami 2
Shoutou	2020	Strong sweet aroma and body (koku); a moment of gyokuro-like sweetness, yet clean; sweet floral aroma

Senchado calls it a tea with Uji DNA and lists its origin as a Tamamidori seedling selection; Shoutou found its floral note unlike Soufuu's. MJGT brewed 4 g in 60 ml at 80 °C (176 °F) for 1 minute. Ito suggests about 60 °C first, as for gyokuro, then 80 °C or more.

The disagreement. MJGT wrote "It isn't bitter at all." Senchado gave three stars for bitterness against two each for sweetness and umami, with no scale shown. Different lots, harvest years and brewing: I won't merge them into one profile.

Frequently asked questions

Is Z1 a registered tea cultivar?

No. Z1 is a breeding-line code that never became a named cultivar. The Cha Norin list writes it only as a parent, and Senchado Tokyo lists it as unregistered under both the Norin system and the Seed and Seedling Act.

Where does Z1 tea come from?

NARO's records say Z1 was selected from seedlings of Tamamidori, Cha Norin No. 4, at the National Tea Research Station. Its pollen parent is unknown, a natural cross.

Is Z1 related to matcha?

Through its descendants. Z1 is the mother of Fuushun, and Fuushun is the mother of Seimei, which NARO bred for sencha, kabusecha, matcha and powdered tea. No source I read describes matcha made from Z1 itself.

Is Z1 the same as Yamatomidori?

The records do not support it. Yamatomidori is Cha Norin No. 10, bred in Nara from Nara native seedlings. NARO describes Z1 as a Tamamidori seedling bred at the National Tea Research Station, so the mother line and the breeding place both differ.

Where can I buy Z1 tea?

It is rare. Senchado Tokyo offered a single-origin Z1 sencha from Wazuka, Kyoto, in 2019, and Shinkoju in Saitama lists Z 1 in its cultivar menu. One with Tea does not sell Z1.

A note from me

To be straightforward with you: One with Tea doesn't sell Z1, and I haven't tasted it. The photos on this page aren't Z1 either. Our own organic ceremonial matcha isn't labeled with Z1, Saeakari or Seimei, so please don't read one into the other.

What stays with me is how Z1 lives on. It never got a name, only a trial code, and the trade remembers it as a plant that faded. Yet its line runs through Fuushun to a cultivar bred for the matcha bowl. Some of us are known less by our names than by what we pass on.

Sources

• Yamaguchi Satoshi et al., 煎茶用新品種'ふうしゅん'の育成 (A New Cultivar, 'Fushun', for Green Tea), Bulletin of the National Research Institute of Vegetables, Ornamental Plants and Tea, Series B (Tea), No. 5, pp. 1-13 (March 1992). Z1's origin and Fuushun's breeding steps. Retrieved 18 September 2026.
• Yoshida Katsuyuki et al., 炭疽病・輪斑病複合抵抗性のやや早生緑茶用品種'さえあかり'の育成, Bulletin of the National Institute of Vegetable and Tea Science No. 11, pp. 73-88 (2012). Saeakari's pedigree, selection and dates. Retrieved 18 September 2026.
• Yoshida Katsuyuki et al., New Green Tea Cultivar 'Seimei' for Sencha, Kabuse-cha, Matcha and Powdered tea, Bulletin of the NARO, Fruit Tree and Tea Science 2: 61-81 (2018). Seimei's pedigree, traits and uses. Retrieved 18 September 2026.
• NARO, 茶品種ハンドブック 第6版 Version 2 (tea cultivar handbook, 6th edition, updated August 2022). Pedigrees, traits and name origins. Retrieved 18 September 2026.
• NARO, さえあかり, cultivar record. Z1's description, Saeakari's numbers. Retrieved 18 September 2026.
• NARO, 緑茶用新品種「さえあかり」, 2009 research result. Z1 as seed parent; resistance tests. Retrieved 18 September 2026.
• NARO, 緑茶用やや早生品種「さえあかり」, press release, 6 August 2010. Z1's traits, Yabukita's share. Retrieved 18 September 2026.
• MAFF, 多収・高品質な複合病害抵抗性の緑茶用品種「さえあかり」, 最新農業技術・品種2019. Saeakari's disease resistance and organic suitability. Retrieved 18 September 2026.
• Minorien (host), 附表１ 茶農林登録品種一覧, the Cha Norin registered cultivar list (PDF). Register rows for Z1's relatives. Retrieved 18 September 2026.
• Ricardo Caicedo, The Z1 Tea Cultivar, My Japanese Green Tea, published 30 May 2017. Origin, registration story, taste remarks. Retrieved 18 September 2026.
• Ricardo Caicedo, Rishouen Z1 sencha review, My Japanese Green Tea, published 6 June 2017. Tasting notes and brewing. Retrieved 18 September 2026.
• 煎茶堂東京 (Senchado Tokyo), コク・香りに優れるが栽培難易度が非常に高い品種。008 Z1, 19 April 2019, merchant page. Status, grower and tasting notes. Retrieved 18 September 2026.
• 伊藤尚哉 (Ito Naoya), Japanese tea instructor, とっても珍しい品種『Z1』を淹れてみた！, note, 5 October 2018. Age estimate, grower and tasting notes. Retrieved 18 September 2026.
• 日本茶教室 松濤 (Nihoncha Kyoshitsu Shoutou), 煎茶 Z1（ゼットワン）, tea school blog, 15 February 2020. Name, rarity, tasting notes. Retrieved 18 September 2026.
• 心向樹 (Shinkoju), Z 1 (ゼットワン), merchant page. Cultivar menu listing やまとみどり and Z 1 separately. Retrieved 18 September 2026.
• Akiyamaen (秋山園), 品種茶 商品概要 (single-cultivar tea page). Its description of Meiryoku's parentage, quoted as a possible source of the Yamatomidori confusion. Retrieved 18 September 2026.