Phytolacca yunnanensis X. H. Li & W. Zhou, 2020

Li, Xin-Hua, Zhou, Wen, Guo, Jia-Cheng & Yin, Xiao-Ming, 2020, Phytolacca yunnanensis (Phytolaccaceae), a new species from China with distinctive inflorescence characteristics, Phytotaxa 446 (1), pp. 49-54 : 51-52

Phytolacca yunnanensis X. H. Li & W. Zhou , sp. nov. ( Figs. 1‒3 ).

Type: — CHINA. Yunnan Province: Jianchuan County, Jinhua Town, near Jingfeng Park, roadside, 2171 m a.s.l., 26°31′57.78 = N, 99°54′ 9.36 = E, 16 October 2018, Li & Zhou 181005 (holotype NAU!)

Diagnosis: ― Phytolacca yunnaensis is characterized in having translucent multicellular trichomes on the peduncles, raches, and pedicels of both racemose inflorescences and infructescences which represents an unique character in the genus Phytolacca . On the other hand, P. yunnanensis resembles P. acinosa ( Fig. 4 ) sharing the free carpels, but differs from it by the 4–5-carpellate gynoecia. P. yunnaensis is also similar to P. exiensis in the number of carpels, but can be easily distinguished from the latter by the distinct carpels. Outside China, P. yunnanensis shares the similarity with P. dodecandra in possessing five free carpels of the gynoecia, but the African congener differs easily from this new species by having sprawling shrubby or herbal habits, and dioecious racemes ( Nowicke 1968, Adams et al. 1989).

Description: ― Perennial herbs to 0.8 m tall, with sparse translucent trichomes on stems, branches, petioles and veins of leaves. Taproots obconic, stout. Stems terete, greyish green. Leaves alternate; petioles 1.5–4.5 cm; leaf blades elliptic or obovate-elliptic (10–23 × 3–7 cm), with prominent dense white raphis below, entire or slightly undulate, base cuneate, apex acuminate. Racemes erect, 8–15 cm long, shorter than the opposite leaves, 36–75-flowered; peduncles 1.5–3.0 cm long; peduncles and raches pink or purplish red, all covered with persistent dense translucent trichomes. Flowers 5–7 mm in diameter; pedicels 5–9 mm, pink, with persistent dense translucent trichomes; tepals 5, pinkish, pink or purplish red, obovate or obovate-oblong, apex acute; stamens 6–10; gynoecia (3‒)5(‒6)-carpellate, free; ovary superior. Berries oblate, 6–7 mm in diameter, fruitlets 3–6, ovate-ellipsoid, purplish black or black. Seeds shiny black, lenticular, 3–4 mm broad.

Etymology: ―The specific epithet refers to Yunnan Province.

Phenology: ―Flowering time July–October, fruiting time August–November.

Distribution and habitat: ―Only one mature plant of this new species has been found growing beside an evergreen hedge of Euonymus japonicus Thunberg (1780: 208) in Jinhua Town (Jianchuan County, Yunnan Province, China). The first author (X.-H. L.) had been to this site of Jinhua Town three times in autumns between 2012 and 2014, but had not noticed this plant of P. yunnanensis . In October 2018, we carried out field surveys in Jinhua Mountain adjoining Jinhua Town in search for wild populations of P. yunnanensis , however, we failed to find it there. As a result, we concluded that the occurrence of the single mature individual of P. yunnanensis was probably resulted from the introduction and cultivation of the hedge shrub, E. japonicus , which is a very popular ornamental shrub in many montane nurseries of northwestern Yunnan Province. Since the berries of P. yunnanensis are attractive to frugivorous birds, and the birds may disperse its seeds into the soil seed bank beneath the shrubs of E. japonicus . This new species is probably endemic to northwestern Yunnan Province.

Key to species of Phytolacca from China: ―After our discovery, six species of Phytolacca are now recorded in China. A diagnostic key is followed below:

1. Inflorescence and infructescence pendulous or arciform ............................................................................................... P. americana

- Inflorescence and infructescence erect ............................................................................................................................................. 2

2. Inflorescence with dense translucent multicellular trichomes, carpels usually 5, free ............................................... P. yunnanensis

- Inflorescence glabrous........................................................................................................................................................................3

3. Carpels 7−8, free ................................................................................................................................................................. P. acinosa

- Carpels 4−10, connate ........................................................................................................................................................................4

4. Carpels 4−5.......................................................................................................................................................................... P. exiensis

- Carpels 6−10.......................................................................................................................................................................................5

5. Stamens usually 10, seeds with slender concentric striations ............................................................................................ P. japonica

- Stamens 12−16; seeds smooth......................................................................................................................................... P. polyandra

Figures

FIGURE 1. Habitat and the distinctive infructescence of Phytolacca yunnanensis. A. Holotype in the wild, B. A ripe infructescence, showing the black 3‒6, usually 5 free fruitlets, and the densely granular surface of the rachis and the peduncle. Photos by Xin-Hua Li.

FIGURE 2. Morphology of Phytolacca yunnanensis. A. A developing infructescence showing the free 4 to 5-carpelled gynoecia, B. Dense translucent trichomes on the rachis of infructescence, C. Persistent tepals below the berry, D‒G. Berries consisting of three to six fruitlets, H. Seed. Scale bars: A = 1 cm, B‒H = 1 mm. Photos by Xin-Hua Li (A), and Jia-Cheng Guo (B‒H).

FIGURE 3. SEM observations of the rachis and fruit stalk of infructescence of Phytolacca yunnanensis. A‒B. Dense multicellular trichoms on the rachis, C‒D. Dense multicellular trichoms on the fruit stalk.

FIGURE 4. Morphology of the infructescence of Phytolacca acinosa. A-B. Glabrous peduncle and the free, usually 8-carpelled gynoecia, C. Glabrous raches, pedicels and the free, 7–8-carpelled gynoecia. Photos by Xin-Hua Li.