Salix zhixiangiana Z.F. Zhan & D.M. Zhang, 2025

Zhan, Zhenfeng, Shang, Ce, Shao, Longzhu, Luo, Yike, Zheng, Baojiang & Zhang, Yue, 2025, Salix zhixiangiana (Salicaceae), a new species from Northeast China, Phytotaxa 701 (2), pp. 199-206 : 200-203

Salix zhixiangiana Z.F. Zhan & D.M. Zhang sp. nov. ( Fig. 1 ) Ṟẇ¨

Type: — China. Jilin: Fusong County, Manjiang town, Fengling, 127°56'41.45"E, 41°46'18.65"N, 1567m, 14 June 2024, fl. ♀, Z. F. Zhan, D. M. Zhang & H. W. Zhang FB 106465 J (holotype: BJFC 00114462!).

Diagnosis: — Salix zhixiangiana is similar to S. arbutifolia , but they can be distinguished in these aspects: as for S. zhixiangiana , dbh of mature individuals can often exceed 1.5 m, bark longitudinally cracked, leaf blade ovate, leaf base rounded, leaf margin distinctly coarsely serrated, stipule conspicuous, filaments longer than bract when fully extended; as for S. arbutifolia , dbh generally less than 1 m, bark peeling in a paper-like strip, leaf blade oblong-lanceolate, leaf base wedge-shaped, leaf margin sparsely serrated or entire, stipule absent, filaments shorter than bract when fully extended. S. zhixiangiana is also similar to S. maximowiczii , but they can be distinguished from S. maximowiczii in these aspects: as for S. zhixiangiana , 2–3 years old branches covered with white powder, upper surface of leaf dark green, stipule obliquely ovate or obliquely lanceolate, infructescence shorter and slanting but not obviously drooping, both female and male flowers have no nectaries, stamens number stable at 5; as for S. maximowiczii , 2–3 years old branches not covered with white powder, upper surface of leaf emerald green, stipule reniform to slightly circular, infructescence obviously drooping, both female and male flowers have nectaries, stamens number 4–8 ( Table 1, Fig. 2 ).

Description: —Trees, 10–20 (30) m tall, dbh (0.5) 1–2 m, trunk straight. Crown pyramidal, ovoid, or irregular cylindrical. Bark longitudinally or deeply longitudinally cracked, grayish-white; 3–4 years old branches light green or reddish-brown, covered with white powder; 2 years old branches reddish, smooth and glabrous, covered with white powder or not; current-year branches green and glabrous. Winter buds ovoconical, 6–8 mm long, dark purplish-red, slightly lustrous and glabrous; bud scale edge imbricate. Leaves ovate or narrowly ovate, 4–9 cm long, 2–3 cm wide, apex acuminate or long acuminate, base rounded or sometimes broadly cuneate, upper surface dark green, smooth and glabrous, lower surface pale green, smooth and glabrous, margin distinctly coarsely serrated; petiole 0.6–1.3 cm long, light green. Stipules obliquely ovate or oblique-lanceolate, 1–2 mm long, glabrous. Tender leaves narrowly ovate to broadly ovate, glabrous or slightly white puberulous at leaf margin, petiole, and dorsal midvein. Catkins open at the same time as young or subadult leaves, diagonally spread when tender, drooping when fully open, cylindrical, 3–6.5 cm long, 5–9 mm wide. Inflorescence peduncle glabrous, 2–5 mm long, with 1–3 leaflets. Bracts of male inflorescences oval or spatulate, 2–5 mm long, white or sometimes apex lavender red, margin and apex densely white pilose; bracts of female inflorescences spatulate obovate, 3–4 mm long, white, apex with microwave-like notch. Staminate flowers 2.5–5 mm long, stamens usually 5, filaments white, glabrous and slightly connate at base, anthers yellow; nectary absent. Pistillate flowers conical, 3–4 mm long; ovary smooth, glabrous and with 4 ovules inside; ovary stalk 0.4–0.8 mm long; style ca. 0.2 mm long; stigmas 0.6-1.2 mm long, primarily divided into two branches, with each branch further deeply bifid; nectary absent. Infructescence slanting, narrow cylindrical, 5–9 cm long. Capsules sparse, 5–10 mm long, bracts and stigmas abscissive.

Distribution: —At present, S. zhixiangiana is only founded in Fengling, Manjiang Town, Baishan City, Jilin Province, China ( Fig3).

Phenology: —The flowering period is from early May to early June. The fruiting period is from early June to July.

Habitat and ecology: —The new species thrives in the fringes of the forest, it occurs at an elevation of 1000– 1750m, and grows on the side of mountain streams or occasionally on the open and wet slopes. Only one population has been found, comprising 1000–2000 healthy mature individuals according to our count, they grow in patches along streams and evenly distributed over 15 km from the foot of the mountain to the summit. A large number of young trees can be seen in the population, which indicates that natural regeneration is in good condition. The common associated plants are S. maximowiczii and Salix rorida Lakschewitz (1911: 131) .

Etymology: —The specific epithet ‘zhixiangiana’ is dedicated to Professor Zhixiang Zhang, a Chinese plant taxonomist who devoted his entire career to the research and education of plant taxonomy.

Paratypes: — China. Jilin: Fusong County, Manjiang town, Fengling , 127°56'41.45"E, 41°46'18.65"N, 1567m, 14 June 2024, Z. F. Zhan & D. M. Zhang FB106465 ( BJFC!), FB106465 A ( BJFC!), FB106465 B ( BJFC!), FB106465 C ( BJFC!), FB106465 D ( BJFC!), FB106465 E ( BJFC!), FB106465 F ( BJFC!), FB106465 G ( BJFC!), FB106465 H ( BJFC!), FB106465 I ( BJFC!), FB106465 K ( BJFC!), FB106465 L ( BJFC!), FB106465 M ( BJFC!), FB106465 N ( BJFC!), FB106465 O ( BJFC!), FB106465 P ( BJFC!), FB106465 Q ( BJFC!), FB106465 R ( BJFC!), FB106465 S ( BJFC!), FB106465 T ( BJFC!), FB106465 U ( BJFC!), FB106465 V ( BJFC!), FB106465 W ( BJFC!), FB106465 X ( BJFC!) ; Fusong County, Manjiang town, Fengling , 127°56'34.36"E, 41°49'7.10"N, 1338m, 27 April 2023, Z. F. Zhan, H. W. Zhang & D. M. Zhang FB106253 ( BJFC!), FB106253 A ( BJFC!), FB106253 B ( BJFC!), FB106253 C ( BJFC!), FB106253 D ( BJFC!), FB106253 E ( BJFC!), FB106253 F ( BJFC!), FB106253 G ( BJFC!), FB106253 H ( BJFC!), FB106253 I ( BJFC!), FB106253 J ( BJFC!), FB106253 K ( BJFC!), FB106253 L ( BJFC!), FB106253 M ( BJFC!), FB106253 N ( BJFC!), FB106253 O ( BJFC!) ; China. Jilin, 16 June 1932, N.D. 6581 ( PE00637543 !) .

Notes: —We have investigated several populations of S. arbutifolia and S. maximowiczii in Northeast China and studied many related specimens. We found that the morphologies of the two species were very stable in their distribution areas. In addition, the key morphologies of S. zhixiangiana were stable at the population level, and we can easily distinguish it from the S. arbutifolia and S. maximowiczii based on them. Therefore, we believe that this species is not a certain ecotype or variety of S. arbutifolia or S. maximowiczii , and it is appropriate to treat the population as a new species-level taxon.

Salix zhixiangiana , S. maximowiczii and S. arbutifolia are sympatric in the distribution area. Salix maximowiczii is mixed in the population of S. zhixiangiana , but the number of the former is very small, and we can differentiate them by examining whether the 2–3 years old branches are covered with white powder, the shape and size of the stipules, the length and pendulous nature of the infructescence, the presence or absence of floral nectaries, and the number of stamens. Salix zhixiangiana and S. arbutifolia are morphologically similar, particularly in the structure of their flowers, they can be distinguished based on morphological traits such as the presence or absence of stipules, the pattern of bark fissuring, and the shape of leaves. Notably, S. arbutifolia is restricted to elevations below the lower distributional limit of S. zhixiangiana , demonstrating complete altitudinal segregation between the two species.

Both male and female flowers of Salix zhixiangiana lack nectaries, and the number of stamens in male flowers is consistently five.These characteristics align with those of S. arbutifolia (sect. Chosenia ) but differ from S. maximowiczii (sect. Urbanianae), whose male and female flowers both possess nectaries, and the number of stamens varies between 4–8 across different florets within the same inflorescence. Consequently, S. zhixiangiana is taxonomically assigned to sect. Chosenia rather than sect. Urbanianae.

Figures

FIGURE 1. Salix zhixiangiana. A. Mature trees, B. Treelet, C. Trunk, D. 3–4 years old branch, E–F. 2 years old branches, G1–G2. Winter buds, H. Stipule, I–J. Young leaves, K. Mature leaves, L1–L6. Staminate inflorescences, M1–M5. Staminate flowers, N. Bract (♂), O1– O4. Pistillate inflorescences, P1–P2. Infructescences, Q1–Q2. Pistillate flowers, R. Ovaries, S1–S2. Capsules, T. Bract (♀), U. Seed.

FIGURE 2. Morphological comparison of Salix zhixiangiana, S. arbutifolia and S. maximowiczii. A–F. S. zhixiangiana. A. Trunk, B. 2–3 years old branch, C. Leaves, D. Stipule, E. Infructescences, F. Staminate flower. G–L. S. arbutifolia. G. Trunk, H. 2 years old branch, I. 3 years old branch, J. Leaves, K. Infructescence, L. Staminate flower. M–R. S. maximowiczii. M. Trunk, N. 2–3 years old branch, O. Leaves, P. Stipules, Q. Infructescences, R. Staminate flower.