Ligularia pyrifolia var. dissecta L. Wang & Q.E. Yang, 2018

Wang, Long, Zeng, You-Pai, Chen, Jun-Ren & Yang, Qin-Er, 2018, Ligularia pyrifolia var. dissecta (Asteraceae, Senecioneae), a remarkable new variety from southwestern Yunnan, China, Phytotaxa 357 (3), pp. 225-229 : 225-227

Ligularia pyrifolia var. dissecta L. Wang & Q.E. Yang , var. nov. Figs. 1 , 2 .

Type:— CHINA. Yunnan: Jingdong County, Jingfu Zhen , Wuliang Shan , 24°19’1.83’’N, 100°42’58.88’’E, humid rocky cliffs, ca. 2200 m, 28 April 2018, Y. P. Zeng & J. R. Chen 31 (holotype IBSC; isotypes IBSC, KUN) .

Stems 1 or 2, erect, 20−50 cm tall, 2.5−3 mm in diameter at base, glabrous proximally, brown puberulent distally. Basal leaves petiolate; petiole to 30 cm long, glabrous, base sheathed; leaf blade ovate, 5−7.5 cm long, 4−10 cm broad, glabrous, both surfaces with prominent palmate veins, base truncate or slightly cordate, 3-palmatisect, segments laciniate-dentate marginally, lobes 2−3-divided. Stem leaves several, similar but smaller, petiolate, with slightly enlarged sheath. Capitula solitary or 2−5 arranged in lax corymb; peduncles to 30 cm long, distally shortly brown puberulent; leaflike bracts linear-lanceolate, 1−1.5 cm long, margin entire; supplementary bracts (bracteoles) to 13, subtending the involucre, linear-lanceolate, ca. 10 cm long, ca. 1.5 mm broad, glabrous or slightly brown puberulent, margin entire. Involucre broadly campanulate, 1.6−2 cm high, ca. 1.5 cm in diameter; phyllaries 10−15, in 2 rows, outer ones lanceolate, 2−3 mm broad, apex acuminate to acute, inner ones oblong to narrowly oblong, 3−4 mm broad, margin brownish or yellowish membranous, apex acute. Ray florets 10−13, yellow; lamina lanceolate to oblonglanceolate, 2−2.5 cm long, ca. 6 mm broad, apex acuminate, irregularly 2−3-denticulate. Tubular florets numerous, 9−11 mm long; tube ca. 3 mm long; limb ca. 4 mm long; style ca. 7 mm long, branches yellow. Achenes yellow, cylindrical, ca. 3 mm long. Pappus brownish, especially so at base, shorter than tubular corolla.

Distribution and habitat:— Ligularia pyrifolia var. dissecta is currently known only from its type locality, i.e. Wuliang Shan in Jingdong, southwestern Yunnan, China ( Fig. 3 ). It grows on humid rocky cliffs at an altitude of ca. 2200 m above sea level.

Phenology:—Flowering from November to April of next year; fruiting from April to May.

Etymology:—The varietal epithet refers to the dissected leaves of the new variety.

Note s:— Ligularia pyrifolia was described by Liu (1985) on the basis of two collections, M.K. Li 1008 (KUN) and M.K. Li 3445 (KUN), with the latter designated as the type. Liu (1985, 1989) referred this species to L. sect. Corymbosae (Franchet 1893: 290) Handel-Mazzetti (1938a: 107) and pointed out that it was very special in the section in having ovate, apically caudate-lanceolate leaves, a lax, corymbiform synflorescence with 3−4 capitula, broadly campanulate involucres (ca. 1.5 cm broad), lanceolate, apically acuminate and 6−7-veined laminae (2−2.5 cm long, up to 6 mm broad) of ray florets, and numerous bracteoles. Almost all these characters have been confirmed by our observations on living plants in the field ( Fig. 4 ), but we found that the capitula are solitary or 2−6 arranged in a corymbiform synflorescence.

Our careful observations on living plants of the two varieties of Ligularia pyrifolia, var. pyrifolia ( Fig. 4 ) and var. dissecta ( Figs. 1 , 2 ), revealed no other essential morphological differences between them except for their distinction in leaf division. The two taxa are currently known only from Wuliang Shan in Jingdong, southwestern Yunnan, China, and both grow on humid rocky cliffs almost at the same range of elevations (1600−2500 m). Although they are most readily distinguishable morphologically, we deem it reasonable to treat them as two varieties under the same species.

The two varieties do not grow together in a single population, and no intermediates have been found on Wuliang Shan.

In the genus Ligularia , the dissected leaves are a rare character occurring, prior to the discovery of L. pyrifolia var. dissecta , only in L. japonica ( Thunberg 1784: 319) Lessing (1832: 390) , L. mortonii ( Clarke 1876: 208) Handel-Mazzetti (1938b: 289) , L. paradoxa Handel-Mazzetti (1922: 140) , L. przewalskii ( Maximowicz 1881: 493) Diels (1901: 621) , and L. qiaojiaensis Chen & Dong in Dong & Chen (2010: 683). The discovery of L. pyrifolia var. dissecta represents the first occurrence of this character within a species in Ligularia , indicating that the leaf division is variable between and within species in this genus. Ligularia japonica is readily distinguishable from L. pyrifolia var. dissecta by the much larger leaves (to 40 cm long, to 40 cm broad vs. 5−7.5 cm long, 4−10 cm broad) and much larger capitula (1−2.5 cm high, 1.5−2.4 cm in diameter vs. 1.6−2 cm high, ca. 1.5 cm in diameter); both L. mortonii and L. paradoxa are distinct from L. pyrifolia var. dissecta by, among other characters, the discoid (vs. radiate) capitula; and both L. przewalskii and L. qiaojiaensis differ markedly from L. pyrifolia var. dissecta by, among other characters, the paniculate synflorescence (vs. capitula solitary or 2−5 arranged in a lax corymb). It seems that the character of dissected leaves have occurred more than once in Ligularia , and apparently it may be controlled by a simple genetic mechanism (one gene or a few) so that the change may occur very easily – as we see, within a single narrowly distributed species. It is worth conducting hybridization experiment to verify this hypothesis.

Figures

FIGURE 1. Ligularia pyrifolia var. dissecta in the wild (Jingdong, Yunnan, China).A. Habitat. B. Habit.

FIGURE 2. Ligularia pyrifolia var. dissecta in the wild (Jingdong, Yunnan, China). A. Basal leaves (adaxial surface). B. Basal leaves (abaxial surface). C. Capitulum (top view). D. Capitulum (back view). E. Capitulum (side view). F. Bracteoles (abaxial surface). G. Outer phyllaries (abaxial surface). H. Inner phyllaries (abaxial surface). I. Ray florets. J. Tubular florets.

FIGURE 3. Distribution of Ligularia pyrifolia var. pyrifolia (●) and of L. pyrifolia var. dissecta (●).

FIGURE 4. Ligularia pyrifolia var. pyrifolia in the wild (Jingdong, Yunnan, China). A. Habitat. B. Habit. C. Basal leaf (adaxial surface). D. Basal leaf (abaxial surface). E. Synflorescence. F. Capitulum (top view). G. Capitulum (side view).