Rehmannia chrysantha M. H. Li & C. H. Zhang.

Yang, Mei-Qing, Wang, Ying-Li, Bai, Xiao-Rong, Li, Min-Hui, Zhang, Chun-Hong & Huang, Lu-Qi, 2016, Rehmannia chrysantha (Rehmanniaceae), a new species from Inner Mongolia, northern China, Phytotaxa 265 (2), pp. 177-181 : 179-180

Rehmannia chrysantha M. H. Li & C. H. Zhang. Type:— China, Inner Mongolia, Baotou city, Jiufeng mountain, 1282

m, 40°42’34”N, 110°43’32”E, 17 May 2014, M. H. Li, C. H. Zhang, et al. 20140517-01 (holotype, PE!; isotype, PE) .

Figs. 2 & 3.

Diagnosis: Rehmannia chrysantha is distinguished from the closely related R. glutinosa by the yellow corolla (vs. purple-red corolla in R. glutinosa ), green or light green calyx (vs. purple-red calyx in R. glutinosa ) and short stem up to 15 cm high (vs. long stems up to 30 cm in R. glutinosa ). The leaves of R. chrysantha are abaxially green, while the leaves of R. glutinosa are red to purple.

Perennial herbs, densely white puberulous and fimbriate; stems erect, 4–15 cm high, unbranched or rarely branched. Leaves rosulate at the stem base, 3.1–12.2 × 1.9–4.2 cm, reducing into bracts upward along the stem. Rosette leaves elliptical to obovate-oblong; surface ventrally green, dorsally light green to greenish white; leaf veins concave above with pale stripes, bulge below; margins deeply lobed and crenate to serrate irregularly; apex obtuse; base cuneate, narrowing gradually and terminated as pedicels with wings. Inflorescences in axillary racemes or solitary flowers. Flowers with robust and erect pedicels, shorter than the bracts; calyx green or light green, persistent, with expanded upper part 1.2–1.7 cm long, lobes 5, shallow, deltoid; corolla yellow, with sparse mixed glandular and eglandular trichomes on lobes, tube 3.9–4.5 cm long, with unexpanded basal portion 0.3–14.1 mm in diameter, gradually expanded above the attachment point of stamens to ca. 2.2 mm in diameter at the mouth; lobes slightly two-lipped, in ‘3+2’ arrangement, two adaxial lobes broadly rectangular rounded, 0.8 × 0.9 mm; three abaxial lobes ovate, 0.5 × 0.5 mm; stamens 4, inserted at the base of corolla tube, exserted, filaments 1.2–1.7 cm long, anthers pubescent, minutely pubescent, flattened and rectangle-rounded; ovary eglandular-efimbriae, style ca. 0.46 mm long, glabrous, stigma expanded. Capsule narrowly ovoid, 1–1.5 cm.

Phenology: Flowers from April to May, and fruits from May to June.

Distribution and habitat: Only known from the type locality in Baotou city, Inner Mongolia, China. Grows on mountain slopes at ca. 1280 m.

Etymology: The epithet refers to the yellow-colored corollas.

Taxonomic notes: Rehmannia chingii , R. elata , R. glutinosa and R. piasezkii have purple-red corollas, while R. henryi Brown (1909: 262–263) has a yellowish corolla. The corolla of R. chrysantha is yellow on both sides. All known species of Rehmannia are taller than 10 cm, as follows: R. chingii is 30–60 cm, R. elata is ca. 150 cm, R. glutinosa is 10–30 cm, R. henryi is 15–40 cm and R. piasezkii is 30–100 cm ( Hong et al. 1998). We measured the height of various individuals of R. chrysantha from May/2014 to July/2015 and found that the height of R. chrysantha ranges from 4 cm to 15 cm. Rehmannia glutinosa is the only Rehmannia species distributed in Inner Mongolia ( Ma et al. 1980).

The new species is closely related to R. glutinosa and R. solanifolia based on molecular data. However, R. chrysantha is quite different from the former in its yellow corolla, green or light green calyx and short stem. Rhemannia solanifolia differs from R. chrysantha by its caducous basal leaves and stout, erect pedicel sub-parallelling the stem. Furthermore, its distribution area is constrained to Sichuan province. Rehmannia henryi is the only other species of Rehmannia with yellow corolla, but its flowers have one or two bracteoles (vs. bracteoles lacking in R. chrysantha ). Based on morphological and molecular evidence, the description of the new species is supported.

Overall, R. chrysantha is morphologically similar to R. glutinosa , except from the dorsally light green to greenish white leaves (vs. dorsally red to purple leaves in R. glutionsa ), green sepals (vs. purple-red sepals in R. glutionsa ), yellow corolla (vs. purple-red corolla in R. glutionsa ), and short stem. R. chrysantha is also morphologically similar to R. solanifolia . However, these species differ by the deciduous basal leaves (vs. persistent basal leaves in R. chrysantha ), stout pedicel (vs. pedicel slender in R. chrysantha ), erect and subparallel to stem in R. solanifolia (vs. ascending to stem in R. chrysantha ). In addition, the flowers of R. solanifolia are 5–6 lobed and include 4–5 stamens, while the flowers of R. chrysantha are exclusively 5-lobed and always with 4 stamens.