Bull. Natl. Mus. Nat. Sci., Ser. B, 38(1), pp. 1–10, February 22, 2012

Taxonomic Studies of Cirsium (Asteraceae) in Japan XXIII.
A New Species from Hachiôji, Tokyo Prefecture, Central Japan
Yuichi Kadota
Department of Botany, National Museum of Nature and Science,
Amakubo 4–1–1, Tsukuba, Ibaraki 305–0005, Japan
E-mail: kadota@kahaku.go.jp(Received 14 November 2011; accepted 28 December 2011)

Abstract A new species, Cirsium tamastoloniferum Kadota is described from a small marshy
land in Hachiôji, Tokyo Pref., central Honshu, Japan, as a member of subsect. Reﬂexae (the Cirsium
kagamontanum group), sect. Onotrophe of the genus Cirsium. Cirsium tamastoloniferum is similar
to C. tenuipedunculatum Kadota described from Yamanashi Pref., Chubu District, central Honshu,
in having hardly glutinous involucres and paniculate inﬂorescence with small, numerous heads,
however, the former is distinguished from the latter by gynodioecy, subterranean stolons, ovate tobroadly ovate cauline leaves with ascending lobes and inner and involucral phyllaries with shortrecurved apices in hermaphrodite plants or with short-ascending apices in female plants. Cirsium
tamastoloniferum is a dweller of marshy lands exceptionally in the Cirsium kagamontanum groupand occurs in Tokyo and Kanagawa Prefs., Kanto District, central Honshu, Japan.
Kew words : Cirsium tamastoloniferum, Cirsium tenuipedunculatum, Japan, new species, wetland.

This is part of a revisional work on JapaneseCirsium (Asteraceae) (Kadota, 1989–2011;
Kadota and Nagase, 1988). In this paper a new
species of subsect. Reﬂexae (Kitam.) Kadota ofsect. Onotrophe (Cass.) DC. from the suburbs ofTokyo Metropolitan City will be described.
Sect. Onotrophe subsect. Reﬂexae (the Cirsium
kagamontanum group) of the genus Cirsium ischaracterized by the absence of radical leaves atanthesis, nodding, small, numerous capitula, narrowly cylindrical involucres and the ploydy levelof 2n＝2x＝34 and is morphologically diversiﬁed in Honshu and Shikoku, Japan (Kadota,
1995a, 1995b, 2007b, 2009a, 2009c, 2011). The
members of the Cirsium kagamontanum groupmostly occur in and along the edges of summergreen forests.
In January 2011 specimens and images of athistle collected from Hachiôji, Tokyo Pref., central Honshu, Japan, were sent to me by Mr.

Hideshige Uchino, Nagaike Park Nature Center,
Hachiôji. This thistle seemed to be included in
the Cirsium kagamontanum group because it had
paniculate compound inﬂorescences with small,numerous heads and narrowly cylindrical involucres. Then I asked Mr. Uchino to send living rhizomes to me. Next I transferred the rhizomes toProf. Dr. Tsunehiko Nishikawa, Hokkaido University of Education, Asahikawa, to count chromosome numbers. Later Dr. Nishikawa clariﬁedthat this thistle has a chromosome number of
2n＝2x＝34 (a diploid). Therefore it was concluded that the thistle in question belongs to theCirsium kagamontanum group due to the chromosome number and the morphological attributes. After the herbarium examinations it wasrecognized that the same thistles were collectedfrom also Ayase-shi, Kanagawa Pref. neighboring to Tokyo Pref., central Honshu, Japan. The
Kanagawa specimens have stolons as already2

Yuichi Kadota

annotated by the collector, Mr. Hideo Takahashi.
Any stoloniferous species are hitherto notreported within the Cirsium kagamontanumgroup.
In October 2011 ﬁeld survey was executed in
Hachiôji under the guidance of Mr. Uchino. The
thistle was found among the Tama Hills, in thewestern suburbs of Tokyo Metropolitan City. The
habitat of the thistle was located around theupper stream of a small valley where marshy
lands were found. Such a landscape is called“Yato (Yatsu)” in Kanto District, central Honshu.
There usually exist damp places at Yato and several endangered plants are frequently foundthere; Rotala mexicana Cham. & Schltdl.
(Lythraceae), Lysimachia vulgaris L. var. davurica (Ledeb.) R. Knuth (Primulaceae), Nabalus
tanakae Franch. & Sav. ex Y. Tanaka & Ono(Asteraceae), etc. (Uchino, pers. comm.). As aresult of the ﬁeld observations it was conﬁrmedthat the thistle is stoloniferous (Fig. 4). Furthermore it was also shown that the thistle is gynodioecious since female plants were additionallyfound there (Fig. 3C).
In this way this thistle is unique among thespecies of the Cirsium kagamontanum group in
having stolons and the occurrence in marshy
lands. The thistle is consequently described here
as a new species, Cirsium tamastoloniferum.
Taxonomic treatment
Genus Cirsium Mill.
Sect. Onotrophe (Cass.) DC., Prodr. 6: 644(1837).
Subsect. Reﬂexae (Kitam.) Kadota, Fl. Jap. IIIa:
148 (1995).
Ser. Reﬂexae Kitam. in Acta Phytotax. Geobot. 3:
5 (1934), p.p.
Ser. Imbricatae Kitam. in Acta Phytotax. Geobot.
3: 5 (1934), p.p.
Cirsium tamastoloniferum Kadota, sp. nov.
[Figs. 1–3]
Cirsium nipponicum (Maxim.) Makino var.
incomptum (Maxim.) auct. non Kitam. ex
Kadota: Hideo Takahashi, Fl. Kanagawa 2001:

1328 (2001).
Differt ab Cirsio tenuipedunculato, habitu
gynodioecio, cum longis stolonibus, foliis
caulinis late ovatis et lobiis foliorum ascendentibus, phyllariis involucrorum breviter patentibus
vel recurvatis.
TYPE: JAPAN. Honshu, Tokyo Pref.,Hachiôji-shi, Utsunuki-machi, Wadauchi, justbelow the Goten-tôge Pass, in a marshy place[35°37′11.7″N 139°20′11.3″E], alt. 146 m,
hermaphrodite, 14 October 2011, Y. Kadota
1113001 (TNS 1134728–holotype; Fig. 1).
A gynodioecious, stoloniferous, perennial, herbaceous plant, ca. 2 m tall or taller. Rootstock
tough and relatively short, horizontal, up to 3 cm
in diameter, with cord-like roots; stolons 30 cm
long or longer, branched. Stem erect sometimes
declining due to dead weight of the inﬂorescences during growth, copiously branched fromthe middle part, leafy, sparingly arachnoid andcovered with short brownish hairs chieﬂy in theupper part, with many ﬂeshy roots just below theground level (Fig. 4); branches elongated at anacute angle. Basal leaves have withered at anthesis. Middle cauline leaves dull green on the adaxial side, glaucous on the abaxial side, soft andslightly ﬂeshy, semi-amplexicaul, not auriculate,shortly petiolate; blades ovate to broadly ovate inoutline, 30–40 cm long, 10–26 cm broad, almost
glabrous on both sides, deeply pinnatilobate tobipinnatilobate, 5–10-jugate; lobes narrowly
ovate, 8–12 cm long, 1.5–3.5 cm broad, ascending at an obtuse angle, with weak, short spines
1–2 mm long; petioles 2–7 cm long. Middle andupper cauline leaves narrowly ovate in outline,
shallowly pinnatilobate, subsessile. Flowers inlate September to early November. Capitula in aloose panicle, nodding sometimes oblique or horizontal or erect in the case of short peduncles,with peduncles 1.5–3 cm long; subtending leaves
ca. 3, linear, 5–20 mm long, with weak spines ca.
1 mm long. Involucres narrowly cylindrical,
19–22 mm long, 5–6 mm (in vivo) and 15–18 mm(in sicco) in diameter, sparingly arachnoid.
Phyllaries 8–9-seriate, shortly patent to shortly
recurved in hermaphrodite plants (Figs. 1, 3B),

A New Cirsium Species from Hachiôji, Tokyo

Fig. 1. Holotype of Cirsium tamastoloniferum Kadota (JAPAN, Honshu, Tokyo Pref., Hachiôji-shi, Utsunuki-machi,
Wadauchi, in marsh, 14 Oct. 2011, Y. Kadota 1113001, TNS 1134728).

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Yuichi Kadota

Fig. 2. Female plant of Cirsium tamastoloniferum Kadota (JAPAN, Honshu, Tokyo Pref., Hachiôji-shi, Utsunuki-machi,
Wadauchi, in marsh, 14 Oct. 2011, Y. Kadota 1113010, TNS 1134746).

A New Cirsium Species from Hachiôji, Tokyo

Fig. 3. Cirsium tamastoloniferum Kadota. A. Habit. B. Hermaphrodite head. C. Female head. All photos taken at
Wadauchi, Ustunuki-machi, Hachiôji-shi, Tokyo Pref., central Honshu, Japan, on 14 Oct. 2011.

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Yuichi Kadota

Fig. 4. Subterranean organ of Cirsium tamastoloniferum Kadota from Wadauchi, Utsunuki-machi, Hachiôji-shi, Tokyo
Pref., central Honshu, Japan, on 14 Oct. 2011. Arrowheads indicate stolons.

ascending at an acute angle in female plants(Figs. 2, 3C); glandular bodies obovato-lanceolate on the inner and middle involucral phyllaries
in hermaphrodite plants, rudimental and degenerative, very slightly glutinous, hardly recognizable in female plants; innermost phyllaries narrowly ovato-lanceolate, 15 mm long; outer
phyllaries narrowly ovate, 5 mm long, clearly
shorter than the inner ones, herbaceous, acute atapex, terminated with weak, short spines ca.
1 mm long. Corollae pale pink in hermaphrodite
plants, deep pink in female plants, 16–17 mm
long; lobes 4 mm long; throats 5 mm long; tubes
7–8 mm long, longer than the throats. Achenes
pale purplish brown to light brown with purplish
lines, 4–4.5 mm long, ribbed, ﬁnely striate; pappus sordid, 10–12 mm long.
Additional specimens examined: JAPAN.
Honshu, Tokyo Pref., Hachiôji-shi, Utsunukimachi, Wadauchi [35°37′N 139°20′E], ca. 150 m,
1 Oct. 2008, S. Uchino A–B (TNS 1113845,

Fig. 5. Somatic chromosomes of Cirsium tamastoloniferum (2n＝2x＝34). Scale＝10 μm. Courtesy ofProf. Dr. T. Nishikawa.

1113850–1113851); Hachiôji-shi, Utsunukimachi, Wadauchi, 26 Nov. 2010, S. Uchino C–D(TNS 1113846–1113849); Hachiôji-shi, Utsunuki-machi, Wadauchi, alt. 146 m, hermaphrodite, 14 Oct. 2011, Y. Kadota 1113008–1113009

A New Cirsium Species from Hachiôji, Tokyo

Fig. 6.

7

Distribution of Cirsium tamastoloniferum Kadota.

(TNS 1134712–11134733); Hachiôji-shi, Utsunuki-machi, Wadauchi, alt. 146 m, female, 14
Oct. 2011, Y. Kadota 1113002–1113007 (TNS
1134749–11134754). Kanagawa Pref., Ayaseshi, Yoshioka, Kitayama, 18 Oct. 1999, H. Takahashi s.n. (KPM NA 117040–117041, 117047–
117048).
Chromosome number: 2n＝2x＝34 (Fig. 5).
Japanese name: Hachiôji-azami (nom. nov.).
Etymology: The word “tama” of the speciﬁcname means a regional name, the Tama area, inwhich the type locality of this new thistle,
Hachiôji City, is located.
Distribution: Central Honshu (Tokyo andKanagawa Prefs.; Fig. 6). Endemic to Japan.
Note: Within the Cirsium kagamontanumgroup C. tamastoloniferum resembles C. tenuipedunculatum Kadota [C. effusum auct. Jpn., cf.
Kadota, 1993; Fig. 7] described from the Misaka
Mountain Range, Yamanashi Pref., Chubu District, central Honshu, Japan, in having hardly

glutinous involucres and paniculate inﬂorescencewith small, numerous heads. However, C. tamastoloniferum is distinguished from C. tenuipedunculatum by gynodioecy, the presence of subterranean stolons, narrowly ovate to oblong-ovate
leaves with lobes ascending at an obtuse angle
and inner and involucral phyllaries with strongly
recurved, caudate tips. Furthermore C. tamastoloniferum grows in marshy lands of lower elevation while C. tenuipedunculatum occurs in herbal
stands and along the edges of summer-green
woodlands in the montane zone (the Fagus crenata zone). In C. tenuipedunculatum plants ofnorthern populations tend to be provided withglutinous involucres with well developed glandular bodies on the inner and middle phyllaries(Kadota, 2009d).
In lowlands of Kanto District, central Honshu,
Japan, another species, C. tonense Nakai [＝C.
nipponicum (Maxim.) Makino var. incomptum(Maxim.) Kitam. ex Kadota], is predominant in8Yuichi Kadota

Fig. 7. Cirsium tenuipedunculatum Kadota. Left. Habit. Right. Head. Photos taken at Mt. Mitsutôge-yama, Yamanashi
Pref., central Honshu, on 14 Oct. 2010.

the genus Cirsium and has been frequently confused with C. tamastoloniferum. Cirsium tonense
is a member of the tetraploid species group(2n＝2x＝68) and is morphologically different
from C. tamastoloniferum by the inﬂorescenceshape (racemose vs. paniculate), the involucral
shape and size (cylindrical and thicker vs. narrowly cylindrical and thinner), the direction ofouter and middle involucral phyllaries (strongly
long-recurved to long-spreading vs. shortly
recurved in hermaphrodite plants and ascendingin female plants). Cirsium tonense prefers drier
habitats (e.g., along the edges of ever-green andsummer-green woodlands) and does not occur inmarshy places.

Acknowledgments
I wish to show my sincere thanks to Mr.
Hideshige Uchino, Nagaike Park Nature Center,
Hachiôji, for his kind gifts of specimens andimages of Cirsium tamastoloniferum and his
guidance to the locality of this thistle; to Prof.
Dr. Tshunehiko Nishikawa, Hokkaido Universityof Education, Asahikawa, for his count and taking photographs of the somatic chromosomes ofthis thistle; to Mr. Hideo Takahashi, Yokohama,for his useful information for the thistle at Ayase,
Kanagawa Prefecture; to Mr. Teruo Katsuyama,
Kanagawa Museum of Natural History (KPM),
Odawara, for the loan of the thistle specimensfrom Ayase; to Dr. Hidetoshi Nagamasu, The

A New Cirsium Species from Hachiôji, Tokyo

Kyoto University Museum, Kyoto University, for
his checking the Latin description.
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