Artemisia nortonii Pampanini (1927: 683)

Guo, Xin-Qiang, Wang, Long & Yang, Qin-Er, 2022, Rediscovery of Artemisia nortonii (Asteraceae, Anthemideae) and clarification of its type locality and geographical distribution, Phytotaxa 570 (3), pp. 283-288 : 285-287

Artemisia nortonii Pampanini (1927: 683) . Figs. 1–3 .

Type:— CHINA. Xizang: Tingri county, Dzaka Chu (= Zhaga Qu ), stony ground, alt. 3840 m, 6 July 1922, E. Norton ( Mt. Everest Exped. 1922) 325 (holotype K000891832 !). Fig. 3 .

Description:—Herbs, perennial, 5–25 cm tall. Rhizome woody, robust, to 1 cm in diameter. Stems few or numerous, erect, rarely branched, gray pubescent. Basal stem leaves pedunculate, leaf blade oblong or oblong-ovate, 1.5–2 cm long, 0.5–1.5 cm broad, 1-pinnatisect, 2 or 3 segments on each side, segments usually 3-partite, with lobules ovate, gray tomentose on both surfaces; middle stem leaves shortly pedunculate, leaf blade oblong or ovate-oblong, 1- pinnatisect, with oblong or ovate segments 1 or 2 on each side, 0.5–1.5 cm long, 0.2–0.5 cm broad, gray tomentose on both surfaces; uppermost leaves 1-pinnatisect or 3-partite, and leaflike bracts entire, gray tomentose on both surfaces. Synflorescence a raceme or narrow panicle. Capitula obovoid or subglobose, 2–3 mm in diameter, sessile or subsessile. Phyllaries ovate or ovoid, abaxially gray tomentose, midribs green when fresh, with membranous margin. Marginal female florets 3–7, fertile, 2–4 mm long, corolla tubular, apex 2-toothed, style exerted; disk florets 5–10, sterile, 2–3 mm long, corolla tubular, apex 5-toothed. Achenes obovoid.

Distribution and habitat:— Artemisia nortonii is currently known only from Dinggyê and Tingri counties in southwestern Xizang, China ( Fig. 4 ). It grows on stony slopes at altitudes of 3800–5000 m above sea level.

Phenology:—Flowering from July to August; fruiting in August.

Additional specimens examined:— CHINA. Xizang: Dinggyê, L. Wang et al. 2827 (IBSC).

Notes:—In the protologue, Pampanini (1927) referred Artemisia nortonii to A. sect. Abrotanum ( Duhamel 1755: 19) Besser (1829: 222) . Ling (1991) noted that the disk florets in the type specimen of A. nortonii were sterile and thus he moved the species to A. sect. Dracunculus Besser (1835: 8) . Our observations on specimens and living plants in the wild have confirmed the sterility of the disk florets in A. nortonii ( Figs. 1L , 3 ). We therefore agree with Ling (1991) on the sectional placement of A. nortonii .

In the protologue, Pampanini (1927) stated that Artemisia nortonii was related to A. turczaninoviana Besser (1834: 23) , but differed by having smaller plants only 15–20 cm tall, sparsely tomentose, densely and diminutively villous (absolutely not adpressed sericeous), smaller capitula, and particularly, ovate-acuminate (not rounded) innermost bracts and narrower corolla of hermaphrodite florets. The latter has been placed in synonymy with A. rutifolia Stephen ex Sprengel (1826: 488) by Poljakov (1961), a treatment also accepted by Ling (1991) and Ling et al. (2011). According to Poljakov (1961), A. rutifolia belongs to A. sect. Absinthium ( Miller 1754: without pagination) Candolle (1838: 189) by having pubescent receptacles, and differs from A. nortonii by having fertile (vs. sterile) disk florets and pubescent (glabrous) receptacles. Artemisia rutifolia is widely distributed in China’s Xinjiang, and also in Afghanistan, Mongolia, Russia (Siberia) and western Himalayas ( Poljakov 1961).

According to Ling (1988, 1991), the plants from eastern and southern Xizang referred to Artemisia salsoloides Willdenow (1803: 1832) by Hooker (1881) should partly belong to A. nortonii , but actually Hooker did not mention any material from eastern and southern Tibet under this species. He just followed Clarke (1876) to record the occurrence of A. salsoloides in western Tibet. In fact, Poljakov (1961) had pointed out that Hooker’s (1881) report about the occurrence of A. salsoloides in western Tibet is erroneous and that the plants in question should belong to A. wellbyi Hemsley & Pearson (1902: 183) , a species occurring in Xizang and northern India ( Ling et al. 2011). Morphologically A. nortonii is readily distinguishable from A. wellbyi by, among other characters, having 1-pinnatisect (2-pinnatisect) stem leaves with ovate (vs. linear or linear-lanceolate) lobules, and abaxially tomentose (vs. puberulent or glabrescent) phyllaries ( Ling et al. 2011).

Figures

FIGURE 1. Artemisia nortonii in the wild (China, Xizang, Dinggyê). A. Habitat and habit. B. Rhizome and roots. C. Portion of stem. D. Leaves. E. Adaxial side of leaf. F. Abaxial side of leaf. G. Synflorescence. H. Capitula. I. Phyllaries (abaxial side). J. Receptacle. K. Marginal female florets. L. Disk florets.

FIGURE 2. Specimens of Artemisia nortonii. China, Xizang, Dinggyê, L. Wang et al. 2827 (IBSC).

FIGURE 3. Holotype sheet of Artemisia nortonii. Inset: disk floret, sterile.

FIGURE 4. Distribution of Artemisia nortonii (●). The black arrow indicates Tingri county in southwestern Xizang, the true type locality of this species, while the red one indicates Gyaca county (■) in southeastern Xizang, which has been previously wrongly recorded as the type locality of this species.