Bull. Natl. Mus. Nat. Sci., Ser. B, 37(4), pp. 181–191, December 22, 2011

Astilbe longipedicellata (Saxifragaceae), a New Combination
and New Status for Astilbe thunbergii (Siebold & Zucc.) Miq.
var. longipedicellata Hatus. from Kyushu, Western Japan
Shinobu Akiyama* and Yuichi Kadota
Department of Botany, National Museum of Nature and Science,
4–1–1 Amakubo, Tsukuba, Ibaraki 305–0005, Japan* E-mail: Akiyama@kahaku.go.jp(Received 17 August 2011; accepted 28 September 2011)

Abstract Astilbe thunbergii (Siebold & Zucc.) Miq. var. longipedicellata Hatus., described from
Kyushu, is recognized as a distinct species. A new combination, Astilbe longipedicellata (Hatus.)
S.Akiyama & Kadota, is proposed. Morphology, geography and other taxonomic implications are
discussed.
Key words : Astilbe, Astilbe longipedicellata, Astilbe thunbergii var. longipedicellata, Kyushu,
new combination, Saxifragaceae.

The genus Astilbe (Saxifragaceae s. lat.) is distributed disjunctly in eastern Asia and North
America and is more diversified in the former.
Endemic species and varieties are known inJapan and their taxonomic treatment has been attempted by several reseachers (Hara, 1939;
Ohwi, 1953, 1975; Kitamura and Murata, 1961;
Ohba, 1982, 2001).
Three species and varieties of Astilbe arerecorded from Kyushu in western Japan:
A. japonica (C.Morren & Decne.) A.Gray, A.
microphylla Knoll var. microphylla and var.
riparia Hatus., and A. thunbergii (Siebold &Zucc.) Miq. var. kiusiana (H.Hara) H.Hara ex
H.Ohba (Figs. 1 left, 2) (including var. longipedicellata Hatus. [Figs. 1 right, 3]) (Ohba, 2001).
Among them A. microphylla var. riparia and A.
thunbergii var. kiusiana (including var. longipedicellata) are endemic to Kyushu.
Astilbe thunbergii var. longipedicellata, basedon specimens collected from Miyazaki Prefecture (Mts. Shiraiwa-yama [Fig. 4] and Do-dake)and Kumamoto Prefecture (Mt. Kunimi-dake and
Gokanosho), was characterized by having doubly
serrate incised leaves, ovate terminal leaflet withcordate base, loosely flowered paniculate inflorescence, and longer pedicels (2 mm long)(Hatusima, 1968). Hatusima (1968), however, did
not describe the flowers. Ohba (2001) treated var.
longipedicellata as a synonym of A. thunbergii
var. kiusiana, but without commenting on his decision. Towards a revision of the genus Astilbe,
we are studying morphological characters andtheir consistency, making field observations, anddetermining the distribution and ecology of
A. thunbergii var. longipedicellata, and how it
differs from its closest ally, A. thunbergii var.
kiusiana.
Materials and Methods
Field surveys were carried out in 2008. All
specimens collected were deposited in the
Herbarium, National Museum of Nature and Science (TNS). Data were also obtained fromherbarium specimens deposited in KAG, KYO,
TI, and TNS. Flowers taken from herbarium
specimens were examined under a binocular microscope using camera lucida after boiling inwater. The measurement of the terminal leaflet

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Fig. 1. Left. Astilbe thunbergii (Siebold & Zucc.) Miq. var. kiusiana (H.Hara) H.Hara ex H.Ohba (Miyazaki
Pref., Nishi-usuki-gun, Takachiho-cho, Shikimibaru, 16 July 2008). Right. A. thunbergii var. longipedicellata
Hatus. (Miyazaki Pref., Nishi-usuki-gun, Gokase-cho, Mt. Shiraiwa-yama, 16 July 2008).

follows Akiyama and Kadota (2010).

Results of observations
Morphology
Observations were made on living plants andherbarium specimens. Floral, leaf, and inflorescence features are especially relevant for delimiting and separating var. longipedicellata fromsimilar taxa. The characters and characteristics ofvar. longipedicellata are provided in the description.
Flowers: Flowers of A. thunbergii var. longi-

pedicellata usually lack petals (Figs. 5 left, 6A),
although rarely a few rudimentary petals (Fig.
6B), or one petal with a few rudimentary ones
(Fig. 6C), are present. The petals are narrowly
linear-oblanceolate, and ca. 2.8 mm long by ca.
0.3 mm wide (Fig. 6Cc far right). The rudimentary petals are filamentous and 0.3–1.5 mm long
and less than 0.1 mm wide (Fig. 6Bc, Cc left andmiddle). The flowers of Astilbe thunbergii var.
kiusiana always have five petals (Figs. 5 right and
6D, E), as in var. thunbergii, and the petals are
narrowly spatulate, 2.6–3.8 mm long by 0.6–0.7
mm wide (Fig. 6Dc, Ec).

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183

Fig. 2. Astilbe thunbergii (Siebold & Zucc.) Miq. var. kiusiana (H.Hara) H.Hara ex H.Ohba (Japan, Kyushu,
Miyazaki Pref., Nishi-usuki-gun, Takachiho-cho, Shikimibaru, alt. 1113 m, Y. Kadota 0832073, TNS).

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Fig. 3.

Astilbe thunbergii (Siebold & Zucc.) Miq. var. longipedicellata Hatus. (Japan, Kyushu, Miyazaki Pref.,Higashi-usuki-gun, Morozuka-mura, Mt. Kuro-dake, Kagodaki, alt. 1394 m, Y. Kadota 0832023, TNS).

Inflorescence: In var. longipedicellata, theinflorescence is 13–28 cm long, paniculate, with
7–14 lateral branches and sparsely arranged

flowers. In var. kiusiana the inflorescence is 6–15
cm long, paniculate with 1–7 lateral branches or
spike-like without lateral branches, and the flow-

Astilbe longipedicellata (Saxifragaceae), a New Combination and New Status

185

Fig. 4. Holotype of Astilbe thunbergii (Siebold & Zucc.) Miq. var. longipedicellata Hatus. (Japan, Kyushu,
Miyazaki Pref. (prov. Hyuga), Mt. Shiraiwa, alt. 1600 m, Hatusima & Sako 26344, KAG).

ers are compactly arranged. Figure 7 shows thenumber of flowers per 1 cm of inflorescencerachis (in x-axis); 4 to 6 per cm. in var. longipedi-cellata and 9 to 14 in var. kiusiana.
Length of pedicels: The pedicels vary from
1.5 mm to 3.8 mm in length in var. longipedicel-

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Shinobu Akiyama and Yuichi Kadota

Fig. 5. Part of inflorescence with flowers. Left. Astilbe thunbergii var. longipedicellata (Miyazaki Pref.,Higashi-usuki-gun, Morodzuka-mura, Mt. Kuro-dake, 15 July 2008). Right. A. thunbergii var. kiusiana(Miyazaki Pref., Nishi-usuki-gun, Takachiho-cho, Shikimibaru, 16 July 2008).

lata and from 0.4 mm to 1.3 mm in length in var.
kiusiana. Variety longipedicellata has longer
pedicels than var. kiusiana (Fig. 7 y-axis).
Leaves: In var. longipedicellata, the ovate towidely ovate terminal leaflet ranges from 5.1–
12.5 cm long and 3.4–7.7 cm wide, is cordate totruncate to cuneate at the base and has roughly
incised, doubly serrate margins. The narrowly
ovate to lanceolate terminal leaflets of var. kiusiana are 1.8–8.4 cm long, 0.8–3.1 cm wide, arerounded to cuneate or shallowly cordate at thebase and the margins are finely serrate. Figure 8
shows the correlation between the length (excluding the apical part) and the ratio of the length(excluding the apical part) to the width of the terminal leaflet. Except in the length of the terminal
leaflet, where there is an overlap, var. longipedicellata strongly differs from var. kiusiana (inKyushu) and var. thunbergii (in Honshu). The
terminal leaflet of var. longipedicellata is wider
than in both var. kiusiana and var. thunbergii.
Distribution and ecology
Astilbe thunbergii var. longipedicellata is
known from central Kyushu in Miyazaki and Kumamoto Prefectures (Fig. 9). In Miyazaki Prefec-

ture it was found in six localities: Mt. Kuro-dake(Morozuka-mura, Higashi-usuki-gun) at the elevations between 1000 and 1394 m; Goyu-zan(Shiiba-mura, Higashi-usuki-gun) at ca. 1650 m;
Mt. Shiraiwa-yama (Gokase-cho, Nishi-usukigun) at 1621 m; Mt. Do-dake (Hinokage-cho,Nishi-usuki-gun); Mt. Wanitsuka-yama (Kitagômachi, Minami-naka-gun), at ca. 1000 m; and
Mt. Sobo-san (Takachiho-cho, Nishi-usuki-gun)at 1020 m. In Kumamoto Prefecture it has
been collected on Mt. Kunimi-dake at 900 m;
Gokanosho at 900–1600 m; Mt. Ichifusa-yama,
at about 1200 m and 1600 m; and Mt. Naidaijinyama. Var. longipedicellata grows on steep limestone slopes.
Astilbe thunbergii var. kiusiana is distributedin Kyushu from Fukuoka through Saga, Oita, Kumamoto and Miyazaki Prefectures to Kagoshima
Prefecture at the elevations between 540 m and1500 m (Fig. 9). Although the ranges of the twovarieties overlap at least on Mt. Wanitsuka-yama
and Mt. Sobo-san in Miyazaki Prefecture, var.
kiusiana grows along forests margins and in noncalcareous soils at the elevations below 1100 m,
except on Mt. Kirishima-yama.

Astilbe longipedicellata (Saxifragaceae), a New Combination and New Status

187

Fig. 6. Flowers of Astilbe thunbergii var. longipedicellata (A, B, C: some stamens removed) and var. kiusiana(D, E: two petals and some stamens removed). A: Y. Kadota 0832048, TNS. B: Y. Kadota 0832049, TNS. C:
Y. Kadota 0832038, TNS. D: Y. Kadota 0832081, TNS (two petals and some stamens removed). E: M. Saito,
10 July 2006, TNS (two petals and some stamens removed). a: Flowers. b: Calyx lobes. c: Petals. d: Stamens.
Bar indicates 1.5 mm for a and 1 mm for b, c, d.

Discussion
Through observations we were able to determine the morphological features, distribution,and ecology of Astilbe thunbergii var. longipedicellata. The most unique feature is the apetalous
flowers. In Asian Astilbe, apetalous flowers werepreviously found only in A. platyphylla H.Boiss.
on Hokkaido and in the Himalayan A. rivularis
Buch.-Ham. The flowers of var. longipedicellata

greatly differ from those of var. kiusiana, which
normally bears petals, and also in the shape andwidth of the petals of var. longipedicellata when
they are present.
The inflorescences with sparse flowers, thelong pedicels, and the roughly incised doubly
serrate, ovate to widely ovate, terminal leaflets
are also characteristic of var. longipedicellata.
These characters are constant and stable. Variety
longipedicellata occurs only in the calcareous

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Shinobu Akiyama and Yuichi Kadota

Fig. 7. Comparison of inflorescences (number of flowers per 1 cm and length of pedicels) between Astilbe thunbergii var. longipedicellata () and var. kiusiana ().

Fig. 8. Comparison of terminal leaflets (length-width ratio and length) between Astilbe thunbergii var. longipedicellata (), var. kiusiana (), and var. thunbergii ().

areas at 900–1650 m elevation in central Kyushu.
Variety kiusiana, also on Kyushu, grows on noncalcareous soils and usually at elevations below
1100 m.
The relatively large morphological differencesclarified here, are not only between var. longipedicellata and var. kiusiana, but also between

var. longipedicellata and var. thunbergii. Astilbe
thunbergii var. thunbergii on Honshu exhibits arather wide range of variation in various characters, but the features of var. longipedicellata areapparently beyond the range of variation of var.
thunbergii. Based on the apetalous condition, an
unusual characteristic in Astilbe, and the mor-

Astilbe longipedicellata (Saxifragaceae), a New Combination and New Status

Fig. 9.

189

Distribution of Astilbe thunbergii var. longipedicellata () and var. kiusiana ().

phological, ecological and distributional discontinuities, we propose that var. longipedicellata berecognized at specific rank as A. longipedicellata(Hatus.) S.Akiyama & Kadota.

Taxonomic treatments
Astilbe longipedicellata (Hatus.) S.Akiyama& Kadota, stat. nov.
A. thunbergii (Siebold & Zucc.) Miq. var.
longipedicellata Hatus. in J. Geobot. (Kanazawa)
16: 56 (1968).
A. thunbergii (Siebold & Zucc.) Miq. var. kiusiana (H.Hara) H.Hara ex H.Ohba in K.Iwats. &al., Fl. Jap. IIb: 45 (2001), pro parte.
Type: Japan. Kyushu. Miyazaki Pref. (prov.
Hyuga), Mt. Shiraiwa-yama, alt. 1600 m (Hatusi-

ma & Sako 26344, KAG–holo).
Paratypes: Japan. Kyushu. Kumamoto Pref.
(prov. Higo), Mt. Kunimi-dake, alt. 900 m (S.
Sako 949, KAG); Momiki, Gokanosho, alt.
900 m (S. Sako 1012, KAG); Kureko, Gokanosho(Hatusima 15010, KAG); Mt. Karimata-yama,
Nihonsugi, Gokanosho, alt. 1200 m (Hatusima& Sako 27879, KAG). Miyazaki Pref. (prov.
Hyuga), Nishi-usuki-gun, Hinokage-cho, Mt.
Do-dake (Hatusima & Sako [& K. Kawanabe]
22531, KAG).
Japanese name: Tsukushi-akashōma (Hatusima 1968).
Rhizomes thick, short creeping. Stems 50–60
cm tall, sparsely reddish brown villous basally.
Radical leaves petiolate; petiole sparsely reddish
brown villous basally; blade bi- or triternate; ter-

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Shinobu Akiyama and Yuichi Kadota

minal leaflet ovate to widely ovate, 5.1–12.5 cm
long, 3.4–7.7 cm wide, base cordate to truncate
to cuneate, margins with double incised serration, lower surface with appressed reddish brownstraight hairs on midvein and lateral veins, uppersurface with sparse white straight short hairs on
veinlets. Flowers July. Inflorescence a panicle,
12–20 cm long, lower lateral axes 7–15, ca. 7 cm
long, with dense short glandular hairs; flowers
sparsely arranged (4–6 flowers per 1 cm). Pedicel
1.5–3.8 mm long. Calyx lobes pale green, ca. 1
mm long. Petals usually 0, very rarely 1, white,narrowly linear-oblanceolate, ca. 2.8 mm long,ca. 0.3 wide, apex acute, base attenuate. Rudimentary petals 0.3–1.5 mm long, less than 0.1
mm wide, filamentous. Stamens 10, 1.5–2.5 mm
long; anthers pale purple before dehiscence.
Ovary semi-inferior, nearly equal to stamens inlength. Capsules ca. 3 mm long.
Habit: Calcareous mountains, in deciduous
forests, 900–1600 m in elevation.
Distribution: Japan, Kyushu (endemic).
Specimens examined. Japan. Kyushu. Kumamoto Pref. Naidaijin-yama (Z. Tashiro s.n.,KYO); at middle elevation of Mt. Ichifusa, about1200 m alt. (M. Tagawa & K. Iwatsuki 3669, 6
Aug. 1960, KYO). Miyazaki Pref. Higashiusuki-gun, Morozuka-mura, Kuro-dake, Kagodaki, alt. 1394 m (Y. Kadota 0832023–0832027, 15
July 2008, TNS); just below the junction between
Kuro-dake and Kagodaki, alt. 1388 m (Y. Kadota
0832028–0832034, 15 July 2008, TNS); 1394 m(Y. Kadota 0832035–0832339, 15 July 2008,
TNS); Kuro-dake, alt. 1120 m (Koga 10735, 25
July 1993, TI); Shiiba-mura, en route from Kubikukuri to Goyuzan, alt. ca. 1650 m (M. Hotta
6554, 17 Aug. 1961, KYO); Minami-naka-gun,
Kitagô-machi, Wanitsuka-yama, ca. 1000 m (Hatusima 32665, 32681, 30 July 1971, KAG);
Nishi-usuki-gun, Gokase-cho (machi), Shiraiwayama, alt. 1620 m (Yukawa 07-23, 8 July 2007,
TNS); 1621 m (Y. Kadota 0832042–0832048,
0832050, 0832051, 0832053, 16 July 2008,
TNS); Takachiho-cho, Sobo-san, 1020 m (Y.
Kadota 0832040, 0832049, 17 July 2008, TNS).

[Appendix]
Astilbe thunbergii (Siebold & Zucc.) Miq.
var. kiusiana (H.Hara) H.Hara [in Nakai &Honda, Nov. Fl. Jap. 3: 19 (1939), as syn.] ex
H.Ohba in K.Iwats. et al., Fl. Jap. 2b: 45 (2001).
Astilbe kiusiana H.Hara in J. Jap. Bot. 14: 49(1938).
Specimens examined. Japan. Kyushu.
Fukuoka Pref. Fukuoka-shi, Sagara-ku, Itaya,
alt. 540 m (Koga 10715, 19 July 1993, KYO, TI);
Itoshima-gun, Mt. Uki-dake (S. Hatusima s.n., 16
July 1933, KAG); Yame-gun, Hoshino-mura, Mt.
Takatori-yama, alt. 750 m (Koga 11917, 23 July
1995, KYO). Saga Pref. Higashimatsu-ura-gun,
Hamatama-cho, Torisu, alt. 620 m (Koga 11909,
9 July 1995, KYO); Karatsu-shi, Ouchi-cho, Mt.
Sakurei-zan (N. Kuroiwa, 22 July 2007, TNS);
Miyaki-gun, Nakahara-cho, Nanamagari-toge,
alt. 540 m (Koga 10717, 19 July 1993, KYO);
Ogishi-gun, Mt. Tenzan (T. Hashimoto 1875, 16
Sept. 1951, TI). Oita Pref. Mt. Sobo-san (S.
Saito s.n., 25 Oct. 1926, TI; M. Arakane H-1326,
8 Aug. 1953, KAG); Kamiyufu (T. Senzan s.n.,
18 Aug. 1925, TI); Mt. Katamuki-yama (M.
Arakane H-1329, 3 Aug. 1962, KAG); Beppushi, Mt. Tsurumi-dake (M. Arakane H-1288, 9
July 1988, KAG), Shidaka-ko (M. Arakane H1324, 1 July 1962, KAG); Hida-shi, Mt. Shutendoji-yama (N. Kuroiwa, 20 July 2007, TNS); Mt.
Okouchi-yama (M. Ono, 15 Sept. 1980, KAG);
Kusu-gun, Kokonoe-machi, Amagaike-goe (M.
Arakane H-1325, 24 July 1965, KAG); Tonomachi, Kamagase (N. Kuroiwa, 16 Aug. 2007,
TNS); Ono-gun, Ogata-cho, Kawakami-keikoku,
605 m (Koga 11871, 25 June 1995, KYO); Takeda-shi, Ogi-machi, Yamazaki (M. Arakane H1289, H-1290, 3 July 1988, KAG). Kumamoto
Pref. Aso-gun, Minenoshyuku, alt. 800 m (M.
Sato 2638, 3 July 1963, KAG), Kusakabe-mura(Naito s.n., 18 July 1923, KAG); Kikuchi-shi,
Kyokushi, Mt. Kura-take, alt. ca. 1050 m (C.
Sato, 9 June 2007, TNS). Miyazaki Pref. Minami-naka-gun, Kitagô-machi, Mt. Wanitsukayama, alt. ca. 1000 m (Y. Kadota 0832011–0832013, 14 July 2008, TNS); Nishi-usuki-gun,Gokase-cho, Iiboshi-toge, alt. ca. 1000 m (M.

Astilbe longipedicellata (Saxifragaceae), a New Combination and New Status

Saito, 10 July 2006, TNS); Takachiho-cho,Gokasho-kôgen, alt. 834 m (Y. Kadota 0832078,
17 July Aug., TNS); Kurobaru, alt. 430 m (Koga
11867, 25 June 1995, KYO); Shikimibaru, alt.
1100 m (M. Saito, 10 July 2006, TNS); alt. 1113
m (Y. Kadota 0832069–0832077, 16 July 2008,
TNS); Mt. Amenokagu-yama (Naito s.n., 15 July
1923, KAG); Between Gokasho and the summitof Mt. Sobo-san, alt. 800 m (S. Hatusima, S.
Sako & K. Kawanabe 22603, 9 Oct. 1958, KAG);
Mt. Sobo-san, alt. 1020 m (Y. Kadota 0832081,
17 July 2008, TNS); (S. Sako s.n., 11 Oct. 1955,
KAG); Hōri and Mt. Ōkue-yama (S. Hatusima& S. Sako 25181, 16–20 Aug. 1960, KAG);
Mt. Kirishima-yama, Mt. Karakuni-dake (K.
Kondo s.n., 21 Oct. 1926, TI). Kagoshima Pref.
Kirishima-yama (Hosoyamada s.n., 15 Oct. 1925,
KAG); (C. Honda s.n., 13 July 1929, KAG); (S.
Sako & Kawanabe 1708A, 16 July 1958, KAG);
Onami-ike (S. Okamoto, 5 Aug. 1951, KYO);
Yunoya-onsen, alt. 700 m (Hatusima 41422, 11
Aug. 1986, KAG).
Acknowledgments
We are deeply indebted to Mr. Masami Saito,
Miyazaki Prefectural Museum of Nature andHistory, for providing materials, information, andhelp in the field observations. We wish to express
our thanks to Ms. Nobuko Kuroiwa and Mr.
Chiyoshi Sato for their gift of materials. Thanks

191

also due to Dr. David E. Boufford, the Harvard
University Herbaria, for critically reading themanuscript, and to the curators of the herbaria
cited in this paper. This study was supported by aGrants-in-Aid for Scientific Research of theJapan Society for the Promotion of Science (no.
21570105 to Akiyama).
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