827. SORBUS HENRYI Rosaceae. Keith Rushforth

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1 827. SORBUS HENRYI Rosaceae Keith Rushforth Summary. Sorbus henryi Rehder from the Mount Omei region in Sichuan, remains a rarity in cultivation. Its nomenclature and taxonomy are discussed. A fruiting specimen and flowers are illustrated. The taxonomy of Sorbus is best described as a bit of a mess. It started fairly well with Linnaeus in 1753, who included both aucuparia and domestica in his concept of Sorbus. Thesetwo species are generally accepted as belonging to different genera today, with Sorbus aucuparia L. and Cormus domestica Spach being the appropriate names. Though clearly not congeneric, they do share one feature which, as far as my research to date has shown, is unique in the Maloideae, that the petiole nodes are five lacunate in all the other genera they are three lacunate, i.e. indicating three vascular traces in the petiole. However, the taxonomy of the genus started to go downhill in 1763, when Crantz transferred Crataegus aria L. to Sorbus. Medikus in 1793 established Hahnia for Crataegus aria, but his attempt was illegitimate as he included his older genera of Aronia, Chamaemespilus and Torminalis within the circumscription of Hahnia and it was left to Host in 1831 validly to create Aria as a new genus, renaming Crataegus aria as Aria nivea Host. In 1874 Decaisne added the genus Micromeles, with the first valid lectotype for this genus being Micromeles rhamnoides Decaisne in Iketani & Ohashi (1993). Unfortunately Aldasoro et al (2004)overlooked Iketani & Ohashi s paper and proposed their own lectotype of Micromeles griffithii Decaisne an acceptable lectotype, but a decade too late. In the two most recent monographs, McAllister The genus Sorbus (2005) restricts Sorbus to those related to Sorbus aucuparia, while Aldasoro et al. (2004) title their paper Revision of Sorbus Subgenera Aria and Torminaria (Rosaceae Maloideae). McAllister s treatment is consistent in that it only deals with the natural group, but in the introduction it does get a little lost in trying to explain the European and West Asian hybrid genera Curtis s Botanical Magazine 2016 vol. 33 (1): pp The Board of Trustees of the Royal Botanic Gardens, Kew

2 without adequately setting them within the subfamily. On the other hand, I find Aldasoro et al frustrating in several ways; my main complaint is that makes no effort to locate the group within the Maloideae and thus fails to compare their subgenera with other genera; however, in spite of some very bizarre identifications, such as Sorbus brevipetiolata Tiep & Yakovlev as being synonymous with Micromeles rhamnoides, it does contain some very useful insights. So why, when I clearly consider that the broad concept of Sorbus is pathologically flawed, is this account headed Sorbus henryi? Simply, the alternate name for this species is Micromeles schwerinii Schneider, first published in 1906 when citing two specimens, Henry 8957 and Giraldi 986. Henry 8957 is listed as specim. florif. and was made when Henry sent his best collector with Antwerp Pratt when he visited western Sichuan, with 8957 being made on the Emei Shan. I have examined the specimens of Henry 8957 at Kew and Harvard, with Aldasoro et al. recording a specimen at Leiden. The Kew specimen, which bears an annotation by Schneider, and was selected as the lectotype by Aldasoro et al. Giraldi 986 is listed as specim. fructif. foliis subtus valde glabrescentibus and recorded as from South Shaanxi. I have not seen a specimen of Giraldi 986, which I believe was collected on or near the Taibei shan in Shaanxi. I have seen sterile material raised from the Swedish expeditions to Taibei shan and growing at Alnarp. This material does not appear to be conspecific with the Emei shan material but in the absence of flowers and fruits this conclusion must be tentative. Alfred Rehder in Plantae Wilsonianae II (1916) rejected both Decaisne s genus Micromeles and Koehne s and Schneider s expansion of the genus both Keohne and Schneider added species to their understanding of Micromeles which included Sorbus alnifolia (Siebold & Zucc.) K.Koch and therefore were in contradiction to Decaisne s concept and transferred the species to Sorbus. As Schneider had named a Japanese plant Sorbus schwerinii (now usually treated as a synonym of Sorbus gracilis K.Koch) he chose to honour Augustine Henry noting that his specimens served as the type of this species Schneider having already named Sorbus giraldiana. 68 The Board of Trustees of the Royal Botanic Gardens, Kew 2016.

3 Plate 827 Sorbus henryi christine battle

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5 A consequence of this renaming, however, is that in any genus other than Sorbus the specific name will revert to schwerinii. So in what genus (or subgenus) should Sorbus henryi be placed? Henry 8957 has entire leaves and petiole nodes three lacunate and thus is not a true Sorbus. However the fruit shows that the placement of the ovules is co-lateral and the fruit covered with round lenticels spaced about four times their diameter apart. The fruit is also 9 13 mm in diameter. These characters are at variance from those exhibited by Micromeles rhamnoides and also Micromeles griffithii and indicate that the species does not belong in Micromeles. The placement of the ovules as co-lateral also excludes the species as being part of Aria, which is best considered as a small European to extreme western Asian genus comprising a single diploid species and some autopolyploids, which have hybridised with Torminalis and Sorbus aucuparia to produce an extensive range of hybrid taxa which are usually apomictic in their breeding pattern. So until the generic limits involving these and other genera, such as Pourthiaea, are better established it is practical to retain henryi in the botanically indefensible Sorbus sensu lato. In Aldasoro et al. (2004) Sorbus henryi Rehder is treated as a synonym of S. hemsleyi (Schneider) Rehder (Micromeles hemsleyi Schneider, Aria hemsleyi [Schneider] Iketani & Ohashi). This follows the Flora of China by Lu & Spongberg (2003), though a sentence at the end of their account of S. hemsleyi notes that Spongberg believes that Sorbus henryi (Micromeles schwerinii) is distinct from S. hemsleyi and should be recognized (as a distinct species). Sorbus henryi clearly has a relationship to S. hemsleyi but it differs in a number of characters: in S. henryi the fruits ripen to a shiny orange and red, whereas in S. hemsleyi they remain a russet green colour. The leaves of S. henryi are doubly toothed or slightly lobulated on the margin in the upper half, (Fig. 1.), whereas in S. hemsleyi the margin is finely serrate to somewhat doubly toothed (fig. 1). The most striking difference, albeit not one shown on the average herbarium sheet, lies in the buds. In S. henryi the buds are rounded ovoid, pointed and generally 5 6( 7) mm in length; in S. hemsleyi the buds are narrow and The Board of Trustees of the Royal Botanic Gardens, Kew

6 Fig. 1. Sorbus henryi. A, leaf underside & margin, 4; B, L.S. flower, petals removed, 4; C, petal, 2; D, seed, with emerging radicle, 4; E, calyx from mature fruit, 6. Drawn by Christine Battle from specimens of Lancaster 465 cultivated Hergest Croft. long pointed, in the range mm on extension shoots but the terminal ones on flowering spur shoots are generally more than 10 mm, slightly more deltoid in shape. Cultivation. Sorbus henryi makes an attractive hardy whitebeam, in average garden conditions. It is in cultivation from collections by Roy Lancaster under L 465 and Keith Rushforth under KR 161, both made on October 12, 1980 from the forest below Leidongping on the Emei shan. Also from the Emei shan it is in cultivation from seeds sent by Shanghai Botanic Garden in 1992 as seedlist number 267 (as Sorbus folgneri) and from EDHCH SICH 1612 and SICH 1622 from the Wawu shan are also in cultivation. The illustration and line drawing by Christine Battle (above) are based on the tree of Lancaster 465 growing at Hergest Croft, Herefordshire. Sorbus henryi Rehder, Plantae Wilsonianae 2: 274 (1915). Micromeles schwerinii C. K. Schneider Ill. Hanb. Laubholzk. 1: 702, fig. 388b, 389a c. (1906). Lectotype: aus Sz tschwan (Emei shan, 1890), lg. Henry 8957 (K). Description. Tree to 15 m. Shoot slightly hairy, with a few scattered, or with no, lenticels. Bud ovoid, pointed, glossy, to 0.7 cm. Leaves cm, obovate, less often elliptic, broadest just above the middle to near apex, apex acuminate usually with a long toothed acumen, base cuneate, margin doubly toothed to lobulate in upper half, simply 72 The Board of Trustees of the Royal Botanic Gardens, Kew 2016.

7 toothed in basal half, margin finely recurved, upper surface with slightly raised dark brown, somewhat hairy veins in pairs, lower surface rugose when young, covered in loose long white hairs when new. Petiole slightly hairy, canaliculate, cm, to 2 cm in mature leaves. Stipules caducous. Inflorescense a corymb of flowers; peduncle less than 1 cm, pedicels lanate; ovary off-white woolly; sepals spreading, slightly hairy; petals densely hairy outside, 4 5 mm; styles (2 )3, close at base. Fruit in lax clusters, cm long & broad, globose, calyx persistent but the tips of the lobes may be worn away by the time the fruit ripens, lenticels 3 5 times apart, top of ovary with some persistent hairs. Distribution. China: western Sichuan. Emei-shan and Wawu shan. Habitat. Forests, m. Specimens: Sichuan, Emei shan: Henry8957 (K, HUH); ibid. Fang Wen-Pei 2722, feet (E, HUH); ibid. Fang Wen-Pei 6120, (E, HUH); ibid. Chow H-C 12459, 1800 m, (HUH); ibid., JiuLauDong,1800m,Tai L-Y 18 (HUH); LeeT.C.3293, tree 6 7 m (HUH); ibid., Lee T. C. 3903, tree 6 7 m, (HUH); ibid., LeeT.C.3913, tree 5 6 m, (H), Rushforth 161 (E). Opien xian, S of Emei: m, Liu Yü-Shih 2088 (HUH); ibid., Liu Y-S 2215, m (HUH). Hong Ya Xian: Wawu National Park, Wa shan, east side, 1950 m SICH 1622 (K). REFERENCES Aldasoro, J.J., Aedo, C., Munoz Garmendia, F., Pando de la Hoz, F. & Navarro, C. (2004). Revision of Sorbus Subgenera Aria and Torminaria (Rosaceae-Maloideae). Systematic Botany Monographs 69: Iketani, H. & Ohashi, H. (1993). New combinations in Asiatic Aria. (Rosaceae-Maloideae-Sorbeae). Journal of Japanese Botany 68(6): Lu, L. & Spongberg, S.A. (2003). Sorbus hemsleyi. In:Wu,Z.-Y.&Raven,P. (eds). Flora of China, Vol. 9. Science Press, Beijing and Missouri Botanical Garden Press, St Louis. p McAllister, H. (2005). The Genus Sorbus. Mountain Ash and Other Rowans, Botanical Magazine Monograph. Royal Botanic Gardens, Kew Richmond, Surrey. Rehder, A. (1916). Sorbus. In: C. S. Sargent (ed.) Plantae Wilsonianae,Vol. 2. Cambridge University Press. Reprinted 1998, Dioscorides Press, Portland, Oreg. p The Board of Trustees of the Royal Botanic Gardens, Kew