Taxonomic treatment
Our phylogenetic analyses revealed that species of Broussonetia sensu Corner (1962) were placed in two clades corresponding to sect. Allaeanthus and sect. Broussonetia, with Malaisia scandens placed sister to the clade of sect. Broussonetia with strongest supports. To correct the paraphyly of Broussonetia sensu Corner (1962), we propose to reinstate the generic status of Allaeanthus Thwaites. Within Broussonetia sect. Broussonetia, B. kaempferi var. australis is synonymized under B. monoica. The species B. kaempferi is not distributed in Taiwan.
Allaeanthus Thwaites, Hooker’s J. Bot. Kew Gard. Misc. 6: 302. 1854.—TYPE: Allaeanthus zeylanica
Allaeanthus zeylanicus Thwaites, Hooker’s J. Bot. Kew Gard. Misc. 6: 303, pl. IX.-B. 1854.—Type: SRI LANKA. Central Province. July 1833, Thwaites—C.P. 2215 (holotype: PDA; isotypes: B [B 10 0294368 image!], FR [FR-0031966 image!], GH [GH00034340 image!], K [K001050115 image!], K [K001050116 image!], L [L. 1583394 image!], MPU [MPU017376 image!]).—Broussonetia zeylanica (Thwaites) Corner, Gard. Bull. Singapore 19: 235. 1962.
Distribution. Sri Lanka.
Allaeanthus luzonicus (Blanco) Fern.-Vill. in Fl. Filip. (ed. 3) 4(13A): 198. 1880; Merrill, Sp. Blancoan. 122. 1918.—Neotype (designated by Merrill 1918, p. 122): PHILIPPINES: Luzon, Laguna Province, Los Baños, 14 March 1914, F.C. Gates & F.Q. Otanes 6663 (Merrill: Species Blancoanae No. 468) (US [00688524 image!]).—Morus luzonica Blanco, Fl. Filip. 703. 1837.—Broussonetia luzonica (Blanco) Bureau in de Candolle, Prodr. 17: 224. 1873; Merrill, Rev. Blancos Fl. Filip. 78. 1905; Corner, Gard. Bull. Singapore 19: 235. 1962; Berg et al., Fl. Malesiana, Ser. I 17(Part 1): 30, fig. 3. 2006.
Allaeanthus glaber Warb. in Perkins, Frag. Fl. Philipp. 3: 166. 1904.—Type: PHILIPPINES. Luzon Isl., Prov. Cagayan, Enrile, O. Warburg 12133 (holotype: B [B 10 0294369 image!]; isotype: NY [00025190 image!]).—Allaeanthus luzonicus var. glaber (Warb.) Merr., Enum. Philipp. Fl. Pl. 2: 37. 1923.—Broussonetia luzonica var. glabra (Warb.) Corner, Gard. Bull. Singapore 19: 235. 1962.
Distribution. Philippines and Indonesia (Sulawesi).
Notes: Type materials of most Blanco’s names, including Morus luzonica Blanco, are not known (Merrill 1918; Nicolson and Arculus 2001). Following Nicolson and Arculus (2001), No 468 of the “illustrative specimen” cited in Merrill (1918)’s Species Blancoanae is here taken as the effective neotypification for Morus luzonica Blanco.
Allaeanthus kurzii Hook. f, Fl. Brit. India 5(15): 490–491. 1888.—Lectotype (designated by Upadhyay et al. 2010, p. 22): MYANMAR (“BURMA”): Herbarium of the late East India Company, Birma, s.d., Griffith (Kew Distrib. 4657) [female plant] (K [K000357622 image!]).—Broussonetia kurzii (Hook. f.) Corner, Gard. Bull. Singapore 19: 234. 1962; Zhou & Gilbert, Fl. China 5: 27. 2003; Berg et al., Fl. Malesiana, Ser. I 17(Part 1): 30. 2006.
Distribution. China (Yunnan), Vietnam, Laos, Thailand, Myanmar, Bhutan, and India (Assam and Sikkim).
Allaeanthus greveanus (Baill.) Capuron, Fiches Bot. Ess. Forest. Madagascar: Fiche 1. 1968; Adansonia, n.s. 12(3): 386. 1972.—Ampalis greveanus Baill. in Grandidier, Hist. Phys. Madagascar t. 293-A. 1891.—Lectotype (here designated): MADAGASCAR. Bekopaka, near Morodava, H. Grevé 254 (P [P00108324 image!]; isolectotypes: P [P00108325 image!], P [P00108326 image!]).—Chlorophora greveana (Baillon) Léandri, Mém. Inst. Sci. Madagascar, Sér. B, Biol. Vég. 1: 18. 1948.—Maclura greveana (Baillon) Corner, Gard. Bull. Singapore 19: 237. 1962.—Broussonetia greveana (Baillon) C.C.Berg, Bull. Jard. Bot. Belg. 47: 356, fig. 21. 1977.
Distribution. Madagascar.
Notes: Of the three collections of Grevé 254 at P, P00108324 is here designated as the lectotype because the label of this collection contains the most information.
Broussonetia L’Hér. ex Vent., Tabl. Régn. Vég. 3: 547. 1799, nom. cons.—TYPE: Broussonetia papyrifera L’Hér. ex Vent.
Papyrius Lam., Tabl. Encycl. 4(2): pl. 762. 1797, nom. illeg.
Smithiodendron H.H. Hu, Sunyatsenia 3(2–3): 106. 1936.
Broussonetia papyrifera (L.) L’Hér. ex Vent., Tabl. Régn. Vég. 3: 547. 1799.—Morus papyrifera L., Sp. Pl. 2: 986. 1753.—Lectotype (designated by Florence 1997, p. 146): [icon] ‘Morus papyrifera’ in Kaempfer, Amoen. Exot. Fasc., 471, t.472. 1712.
Smithiodendron artocarpioideum H.H. Hu, Sunyatsenia 3(2–3): 107–109, pl. 6. 1936.—Type. CHINA: Yunnan, Shih-pin Hsien, 29 May 1933, H.T. Tsai 53462 (holotype: PE [1640641 image!]; isotypes: P [P06885709 image!], PE [00025034 image!], PE [00023979 image!], PE [00934142 image!]).
Distribution. The reported distributions of Broussonetia papyrifera are highly inconsistent across literature (Table 1), confounded by ancient and recent translocations of the species for multiple purposes around the world (Matthews 1996; Barker 2002; Seelenfreund et al. 2010; Chang et al. 2015). The distribution map in Matthews (1996) includes Japan, Korea, China (northern, central, and southern China), Taiwan, Vietnam, Laos, Thailand, Cambodia, Myanmar, India (Sikkim), island Southeast Asia (excluding the Philippines and Borneo), Melanesia, and Polynesia islands. Chang et al. (2015) showed a high chloroplast haplotype diversity in China, Taiwan, and Indochina, suggesting that these regions are likely native range of the species. Zhou and Gilbert (2003) provided a provincial distribution in China (Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandgon, Shanxi, Sichuan, SE Xizang, Yunnan, Zhejiang). In Northeast Asia, the non-native status of B. papyrifera in Japan has been repeatedly reported (Ohwi 1965; Kitamura and Murata 1980; Okamoto 2006) while this species is regarded as native in Korea (Yun and Kim 2009). Historically, the fibrous B. papyrifera had been introduced to Remote Oceanic islands via SE Asian islands (Matthews 1996; Chang et al. 2015); however, its growth and populations in these regions had declined significantly since last century (Matthews 1996). On the other hand, B. papyrifera has been introduced and become naturalized and invasive around the world (Florece and Coladilla 2006; Bosu et al. 2013; Rashid et al. 2014; Chang et al. 2015).
Broussonetia kaempferi Siebold, Verh. Batav. Genootsch. Kunst. 12: 28. 1830; Akiyama et al., J. Jap. Bot. 88: 351. 2013; Ohba & Akiyama, J. Jap. Bot. 89: 127. 2014.—Lectotype (designated by Akiyama et al. 2013, p. 351): [icon] ‘Papyrus spuria’ in Kaempfer, Amoen. Exot. Fasc, t.472, 474. 1712.
Broussonetia kaempferi var. australis auct. non T. Suzuki: Yamazaki, J. Phytogeogr. Taxon. 30(2): 69. 1982; Chang et al., Fl. Reipubl. Popul. Sin. 23(1): 27, pl. 7(9–13). 1998; Zhou & Gilbert, Fl. China 5: 27. 2003.
Distribution. Japan (Shikoku and Kyushu), central to southern China (Anhui, Chongqing, Fujian, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangxi, Yunnan, and Zhejiang), northern Vietnam, and India (Arunachal Pradesh; Naithani 1981).
Notes. Broussonetia kaempferi is not distributed in Taiwan; B. kaempferi var. australis is a synonym of B. monoica. The images of Broussonetia ‘kazinoki’ in Utteridge and Bramley (2015, p. 77, figs. 2 & 6) are a pistillate individual of B. kaempferi.
Broussonetia ×
kazinoki Siebold (in Verh. Batav. Genootsch. Kunst. 12: 28. 1830, nom. nud.) in Siebold & Zuccarini, Abh. Math.-Phys. Cl. Königl. Bayer. Akad. Wiss. 4(3): 221. 1846; Akiyama et al., J. Jap. Bot. 88: 352, fig. 44. 2013; Ohba & Akiyama, J. Jap. Bot. 89: 127. 2014.—Lectotype (designated by Akiyama et al. 2013, p. 352): JAPAN. von Siebold s.n. 1842 (M [M-0120984 image!]).
Broussonetia ×hanjiana M. Kim in Yun and Kim, Korea J. Pl. Taxon. 39: 82. 2009: 82, syn. nov. Type: —KOREA. Province Jeonnam, Is. Gageo, 16 May 2008, M. Kim 9944 (holotype: JNU).
Distribution. Documented from Japan (Kitamura and Murata 1980; Okamoto 2006; Ohba and Akiyama 2014) and Korea (Yun and Kim 2009).
Distribution. Japan and Korea.
Notes. Long regarded as Broussonetia kazinoki × B. papyrifera (Okamoto 2006), the Japanese Kôzo Broussonetia × kazinoki is actually the natural hybrid between B. monoica and B. papyrifera cultivated for paper making since ancient time in Japan and Korea (Yun and Kim 2009; Ohba and Akiyama 2014). Broussonetia × kazinoki is highly variable and “various intermediate forms are known between the parent species (i.e., B. monoica and B. papyrifera) in such features as plant sex (dioecious or monoecious), hairness of young shoots, and leaf shape and texture” (Okamoto 2006). Yun and Kim (2009) reports that B. ×
hanjiana (≡ B. ×
kazinoki) is dioecious. Further study is needed to understand the origins of this natural hybrid.
Broussonetia monoica Hance, J. Bot. 20 (238): 294. 1882; Ohba & Akiyama, J. Jap. Bot. 89: 127. 2014.—Type: CHINA. Guangdong (“prov. Cantonensis”), “Lien chau”, 1881, B. C. Henry 21933 (holotype: BM [BM000895739 image!]).
Broussonetia kaempferi auct. non Siebold: Hayata, J. Coll. Sci. Imp. Univ. Tokyo. 30: 273. 1911; Kanehira, Formos. Trees rev. ed. 146. 1936; Li, Woody Flora of Taiwan 113, fig. 35. 1963; Liao, Quart. J. Exp. Forest. 3(1): 148. 1989; Liu et al., Trees of Taiwan 331. 1994, pro parte; Liao, Fl. Taiwan, 2nd. ed. 2: 140. 1996, pro parte; Lu et al., Trees of Taiwan 2: 95, photos. 2006, pro parte.
Broussonetia kaempferi var. australis T.Suzuki, Trans. Nat. Hist. Soc. Taiwan 24: 433–435. 1934.—Type: TAIWAN. “In silvs secundris ad Heikoko prope Sinten”, T. Suzuki 8362 (“ST 8336”), 2 Apr 1933 (holotype: TAI [118781 image!]).
Broussonetia rupicola F.T. Wang & Tang, Acta Phytotax. Sin. 1(1): 128. 1951.—Type: CHINA. “Szechuan” (Sichuan), Nanchuan, F. T. Wang 10884 (holotype: PE [00760682 image!]), syn. nov.
Broussonetia jiangxiensis X.W Yu, J. Jiangxi Agric. Univ. (1): 3, fig. 2. 1982—Type: CHINA. Jiangxi, Nanchang, X.W Yu 1435 (holotype: JXAU), syn. nov.
Broussonetia kazinoki var. ruyangensis P.H.Liang & X.W.Wei, Bull. Bot. Res., Harbin 2(1): 155–156, fig. 1. 1982.—Type: CHINA. Guangdong: Ruyang, Wu-Zhi-Shan, 600–800 m, 28 Mar 1979, X.-W. Wei 4471 (holotype: CANT).
Broussonetia kazinoki form. koreana M. Kim, Korean J. Pl. Taxon. 39(2): 84, fig. 1F, 1G. 2009.—Type: KOREA. Province Jeonnam, Is. Gageo, 16 May 2008, M. Kim 9946 (holotype: JNU), syn. nov.
Broussonetia kazinoki auct. non Siebold: Liu, Illustrations of Native and Introduced Ligneous Plants of Taiwan 2: 707, pl. 561. 1962; Liu & Liao, Fl. Taiwan 2: 120, 122, pl. 234. 1976; Liao, Quart. J. Exp. Forest. 3(1): 148–149. 1989; Liu et al., Trees of Taiwan 331. 1994, pro parte; Liao, Fl. Taiwan, 2nd. ed. 2: 140, pl. 68, photo 59. 1996, pro parte; Chang et al., Fl. Reipubl. Popul. Sin. 23(1): 26, pl. 7(6–8), 1998; Zhou & Gilbert, Fl. China 5: 26–27. 2003; Lu et al., Trees of Taiwan 2: 95, photos. 2006, pro parte; Yun & Kim, Korean J. Pl. Taxon. 39(2): 84, fig. 1C, 1F, 1G. 2009.
Distribution. Japan (Honshu, Kyushu, Shikoku), Korea, central to southern China (Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Sichuan, Yunnan, Zhejiang), Taiwan, and northern Vietnam.
Notes. Until the lectotypification of Siebold’s Japanese collections (Akiyama et al. 2013) and subsequent taxonomic revision of Japanese Broussonetia (Ohba and Akiyama 2014), this monoecious Broussonetia had long been mis-treated as B. kazinoki, which should be applied to the natural hybrid between B. monoica and B. papyrifera.
Leaves of B. monoica are highly polymorphic, varying considerably even within an individual throughout the growing season (Fig. 1). Specimens of B. monoica bearing undivided obovate to lanceolate leaves (Fig. 1i, j) are extremely similar to and difficult to be distinguished from B. kaempferi; misidentification and confusion of the two species are common both in herbarium collections and the literature. The most important and unambiguous diagnostic character that separates the two species is the shape of staminate catkins, with the dioecious B. kaempferi bearing spicate catkins ca. 1.5–2.5 cm long (Fig. 1n) and the monoecious B. monoica bearing globose ones ca. 1 cm across (Fig. 1c, d). However, based on our field observation, the globose staminate catkins of B. monoica flowers are extremely fragile and caducous during its flowering season in early spring, falling off shortly after their appearance. Consequently, it is highly probable that individuals bearing only the pistillate capitula are misidentified as female plants of B. kaempferi. Under this circumstance, sterile individuals of the two species can be distinguished by their growth habit and leaf morphology. Broussonetia kaempferi is a climbing and often twining liana (Fig. 1l, m) whereas B. monoica is a shrub often with slender twigs (Fig. 1f–h). Leaves of B. kaempferi are thinly chartaceous, narrowly oblong to lanceolate with almost symmetric (sub-)cordate leaf base and undivided and crenate margin. In contrast, leaves of B. monoica are thinly herbaceous and highly variable, ranging from oblique ovate or broadly ovate (Fig. 1a, b, f, g) similar to Morus australis Poir. (e.g., Pl. 68 Liao 1996) to narrowly ovate (Fig. 1i, j) similar to B. kaempferi.