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Research Article
Taxonomic notes on the genus Deutzia (Hydrangeaceae) from Central China
expand article infoSong-Zhi Xu‡, Qi-Liang Gan§, Zhen-Yu Li|
‡ Nantong University, Nantong, China
§ Zhuxi Qiliang Biological Institute, Hubei, China
| Institute of Botany, Chinese Academy of Sciences, Beijing, China

Corresponding author: Zhen-Yu Li ( lizy@ibcas.ac.cn )

Academic editor: Hugo de Boer
© 2023 Song-Zhi Xu, Qi-Liang Gan, Zhen-Yu Li.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: Xu S-Z, Gan Q-L, Li Z-Y (2023) Taxonomic notes on the genus Deutzia (Hydrangeaceae) from Central China. PhytoKeys 220: 51-57. https://doi.org/10.3897/phytokeys.220.96623
Open Access

Abstract

Based on examination of syntype specimens deposited at P, the lectotype for the name Deutzia setchuenensis Franch. is designated here. By consulting literature and specimen records, the type locality of D. setchuenensis var. longidentata Rehder, ‘Chin-Ting shan’ in the protologue is likely a misspelling of ‘Chiuting shan’ which is now called Jiuding shan located in southern Mao county, Sichuan province. In addition, a new variety, Deutzia setchuenensis var. macrocarpa Q.L.Gan, Z.Y.Li & S.Z.Xu from western Hubei, Central China, is described and illustrated. It differs from other varieties of D. setchuenensis Franch. by the orange anthers, broader outer filaments, obtuse inner filaments, and larger fruits.

Keywords

Deutzia setchuenensis, lectotype, new variety, var. macrocarpa

Introduction

Deutzia Thunb. as the second largest genus of the tribe Philadelpheae (Hydrangeaceae), consists of ca. 60 species and is mainly distributed across eastern Asia and Mexico, with ca. 50 species found in China (Hwang et al. 2001; Hufford 2004). Deutzia setchuenensis Franch. and its varieties, which were native to China, were widely introduced as ornamental plants (Hutchinson 1909; Rehder 1940; Brickell and Zuk 1996). Recently, when we were identifying Deutzia specimens from Zhuxi county, Hubei province, we found a wild Deutzia morphologically similar to Deutzia setchuenensis, but with larger capsules. In order to identify this taxon, we have consulted protologue and specimens. However, we found that the type of D. setchuenensis is not designated, evidenced by the fact that all three gatherings (MNHN-P-P04573103, MNHN-P-P04573105 & MNHN-P-P04573106) stored at Muséum d’Histoire Naturelle, Paris (P) (Thiers 2016) were referred as the type. This necessitated designation of a single specimen as the type of this species from the aforesaid syntype. After examinations of syntypes at P, the lectotype of the species is designated in this study. In addition, we found the type locality of D. setchuenensis var. longidentata Rehder remains confused, and ‘Chin-Ting shan’ in the original record is likely a misspelling for Chiuting shan (now Jiuding shan). Finally, after checking Flora of China (Hwang et al. 2001), and relative literature and making comparisons with the specimens of Deutzia stored in PE and some virtual specimen databases (P, A, CVH, and JSTOR), we found that this unknown taxon resembles Deutzia setchuenensis in stem, leaf, flower, fruit and indumentum, white disc, and smaller seeds, but differs from three varieties of D. setchuenensis in the color of anthers, shape of outer and inner stamens, and size of fruits (Hutchinson 1909; Rehder 1911; Hwang 1992, 1995; Hwang et al. 2001). Therefore, we confirm that these peculiar plants represent a new variety of Deutzia setchuenensis, which is described and illustrated here.

Results

Lectotypification of Deutzia setchuenensis Franch

Deutzia setchuenensis Franch. in Journ. De Bot. (Morot) 10: 282. 1896

Type

China. ‘Set-Chuen orientalis, circa Tchen-kéou-tin’ (eastern Sichuan, near Chengkou tin), P. Farges s.n. (lectotype, P, P04573103 designated here; isolectotypes, P, P04573105 & P04573106; photos PE!).

Note

Adrien René Franchet (1896) published the species based on the type collected from Chengkou tin by P. Farges. There are three specimens collected from Chengkou tin by Farges deposited in Muséum d’Histoire Naturelle, Paris (P), and the label data of the specimens were exactly the same as original records, including the collector, collection locality, and all of them were flowering branches. Of them, two specimens (P04573103 and P04573105) were determined by Franchet, while another (P04573106) was determined by Alfred Rehder. It is clear that these three specimens are the syntypes of Deutzia setchuenensis. Based on examination of the syntypes, we selected the more perfect one (P04573103) as lectotype for the species. French missionary and plant collector, Paul Guillaume Farges collected more than 4000 specimens in Chengkou tin from 1892 to 1896 (Bretschneider 1898; Cox 1945). Chengkou tin (1822–1912) was previously located in the administrative division of Qing dynasty, an area renamed Chengkou county since 1913.

Correction of the type locality

Deutzia setchuenensis var. longidentata Rehder in Sargent, Pl. Wils. 1: 8. 1911.

Type

China. western Szechuan (Sichuan): Chiuting shan (original record misspelled it as Chinting), thickets, alt. 1200–1500 m, 25 May 1908, E.H. Wilson 2895 (holotype, A, A0042097; photo, PE!).

Note

According to ‘Plantae Wilsonianae’, from late spring to summer, 1908, E.H. Wilson collected plant specimens along the Min River valleys, and in late May when he was in Jiuding shan (Chiuting shan) around 31°51'N, 103°76'E, southern Mao county, not Jinding (Chinting), the main peak of Emei mountain (29°52'N, 103°33'E).

Taxonomic treatment of new variety

Deutzia setchuenensis Franch. var. macrocarpa Q.L.Gan, Z.Y.Li & S.Z.Xu, var. nov.

urn:lsid:ipni.org:names:77314712-1
Figs 1, 2

Diagnosis

The new variety, Deutzia setchuenensis Franch. var. macrocarpa Q.L.Gan, Z.Y.Li & S.Z.Xu can be easily distinguished from other varieties ( var. setchuenensis , var. corymbiflora (Lemoine) Rehder, var. setchuenensis and var. longidentata Rehder) by its orange anthers (vs. yellow anthers), broadly oblong outer filaments with 2 small repand denticles at apex, the width of teeth is more than twice its length (vs. oblong, with 2 deltoid, oblong or lanceolate teeth at apex, the length of teeth is equal to or more than its width), obtuse apex of inner filaments (vs. 2-dentata at apex), and larger fruits 5–7 mm in diam. (vs. 4–5 mm in diam.).

Figure 1. 

Deutzia setchuenensis var. macrocarpa, var. nov. A plant B, C branches D petioles E leaves F flowering branches G fruiting branches.

Type

China. Hubei Province: Hongyangou village, Quanxi town, Zhuxi county, alt. 850m, 25 June 2022, Q.L.Gan 3306 (fl., holotype, PE!; isotype, PE!).

Paratypes

China. Hubei province: Hengduanshan, Baguashan Natural Reserve, Zhuxi county, alt. 840m, 13 June 2022, Q.L.Gan 3305 (fl., PE!); the same locality, 2 August 2022, Q.L.Gan 3307 (fr., PE!).

Description

Deciduous shrubs, 90–150 cm tall. Old stems pale gray-brown, often with flaky bark; branches erect to spreading; branchlet opposite, sparsely gray stellate pubescent; flowering branchlets 8–14 cm, 6–10-leaved. Leaves opposite, stipules absent; petiole 3–5 mm long, sparsely stellate-pubescent; leaf blades papery, ovate to ovate-lanceolate, 2–10 cm long, 0.6–3 cm wide, base rounded to broadly cuneate, margin serrulate, apex acuminate or caudate-acuminate, adaxial surface green, not gloss, sparsely stellate pubescent, trichomes 2–4-rayed, abaxial light green, trichomes 4–6-rayed; lateral veins 2–4 paired, mid-vein and lateral veins impressed abaxially, and slightly prominent adaxially, veinlets inconspicuous. Cymes 2–3.5 cm long, 2–3 cm across, 6–12-flowered, sparsely stellate-pubescent; peduncle slender; pedicels 3–6 mm long, usually with 1 to 2 bracts at base or around the middle; bracts linear, 3–6 mm long, 0.5–1 mm wide; flower buds spheroical. Hypanthium hemispheric, 2.5–3.5 mm long and wide, densely 10–13-rayed stellate-tomentulose; calyx lobes 5, broadly deltoid, 1–1.5 × ca. 2 mm, apex acute, erect in bud, spreading in anthesis, inflexed and persistent in fruit. Corolla pure white; petals 5, white stellate-pubescent outside. Stamens 10 in 2-series, erect, filaments pure white, dorsiventraly flattened, anthers orange; outer stamens 4–5 mm long, filaments broadly oblong, with 2-repand denticles at apex, the width of teeth is more than twice its length, anthers broadly ovate; inner stamens shorter than outer ones, filaments obtuse at apex, anthers borne near middle of filaments abaxially, the width of anther exceeds the length. Disc annular, flattened, white. Ovary inferior, 2–3-loculed; styles 2–3, 3–3.5 mm long, usually coherent, glabrous. Capsule subglobose, 5–7 mm in diam., densely stellate-tomentulose, 2–3-valved. Seeds numerous, dark brown, ellipsoid or ovoid, 0.6–0.8 mm long, reticulate.

Figure 2. 

Deutzia setchuenensis var. macrocarpa, var. nov. A flowering branch B flower bud C young fruit D flower E outer stamens F inner stamens G capsules H stellate-pubescent on adaxial surface of leaf blade I stellate-pubescent on abaxial surface of leaf blade J stellate-tomentulose on surface of capsules.

Phenology

Flowering from May to June; fruiting from September to October.

Distribution and habitat

Deutzia setchuenensis var. macrocarpa distributes in Quanxi town (Hongyangou village), Baguashan Provincial Nature Protection Area, and Taoyuan town (Hetaoyuan village) of Zhuxi county, Hubei province. It occurs at the edge of sparse thickets or forests on hillsides, or by streams. The main companion species include trees: Phoebe zhennan S. Lee, Sycopsis sinensis Oliv. and Symplocos lucida (Thunb.) Sieb. & Zucc.; shrubs: Rubus swinhoei Hance and Camellia cuspidata (Kochs) Wright ex Gard.; vines: Smilax glaucochina Warb. and Actinidia polygama (Sieb. et Zucc.) Maxim.; and a fern such as Dryopteris fuscipes C. Chr.

Etymology

The Latin name of the variety, ‘macrocarpa’, refers to the large fruit.

Vernacular name

Da Guo Sou Shu (Chinese).

Conservation assessment

Deutzia setchuenensis var. macrocarpa is currently known only from three localities consisting of less than 20 individuals in Zhuxi county, Hubei province. The provisional conservation status is Critically Endangered (CR), based on criterion D (number of mature individuals fewer than 50) (IUCN 2022).

Economic uses

Deutzia setchuenensis has rich intraspecific and morphological genetic diversity (Table 1). In the late 19th century, Deutzia setchuenensis var. setchuenensis and var. corymbiflora (Lemoine) Rehder were introduced into western Europe, and it was found that the ornamental value and winter hardness of the former were inferior to the latter. The new variety has larger flowers and fruits, and utilization of its germplasm is potential.

Table 1.
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Morphological comparisons of four varieties of Deutzia setchuenensis Franch.

Characters var. setchuenensis var. longidentata Rehder var. corymbiflora (E. Lemoine ex Andre) Rehder var. macrocarpa Q.L.Gan, Z.Y.Li & S.Z.Xu
Inflorescence 6–12-flowered 6–12-flowered 12–50 (or more)-flowered 6–12-flowered
Teeth of outer filaments oblong, slightly longer than the anthers lanceolate, much longer than the anthers deltoid, ca. as long as the anthers repand, much shorter than the anthers
Apex of inner filaments 2-dentate 2-dentate 2-dentate obtuse
Anthers yellow yellow yellow orange
Fruits 4–5 mm in diam. ca. 4 mm in diam. ca. 4 mm in diam. 5–7 mm in diam.
Distribution Chongqing, Fujian, Guangdong, Guangxi, Guizhou, Hubei, Hunan, Jiangxi, Sichuan, Yunnan Sichuan (Mao Xian) Hubei (Fang Xian, Badong) Hubei (Zhuxi)

Acknowledgements

This study was supported by the Special Foundation of National Science and Technology Basic Research (2013FY112300).

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