During an investigation of invasive plants, we found a puzzling herbaceous plant population of Asteraceae in Shenzhen, Guangdong. By the foun- dation of related literature^[1-5] and type specimen, it was confirmed that the herb species Porophyllum ruderale (Jacquin) Cassini represented a newly natura- lized genus to China.

Porophyllum Guettard, Hist. Acad. Roy. Sci. Mém. Math. Phys. (Paris, 4). 1750: 377. 1754.点叶菊属

Annual or perennial erect herbs, shrubs or sub- shrubs, with strong smell. Leaves simple, opposite or alternate, sessile or petiolate; leaf blade rounded, elliptic to linear, leaf margin entire to crenate, with transparent glands. Capitula solitary or in lax corymbs. Involucres cylindrical, campanulate or turbinate. Phyllaries 5-10, free to base, 1 series, glandular, oblong to linear. Ray florets absent, disk flowers bisexual, fertile, 10-100 per capitula, corolla 5-lobed. Cypsela fusiform to cylindrical, pappus free bristles, persistent.

About 25 species, distributed in the southwestern United States, Mexico, West Indies, Central America, South America^{[1, 3]}. Recently, one species was found in Guangdong, China. The name of the genus is derived from the Creek word porus and phyllon, meaning pore and leaf, referring to the peculiar glands on the leaf blade of many species of this genus.

Porophyllum ruderale (Jacquin) Cassini, F. Cuvier (ed.), Dict. Sci. Nat. (ed. 2) 43: 56. 1826.  点叶菊(新拟) Fig. 1

(Fig. 1)

Fig. 1 Porophyllum ruderale (Jacquin) Cassini. A: Habitat; B: Plant; C: Seedlings; D: Leaves; E: Capitula; F: Cypsela.

Annual herbs, or subshrubs, 0.7-1.3 m tall, with white latex or not. Leaf alternate or opposite, 1.5-4.5 (5.5) cm×0.5-3 cm; leaf blade ovate, elliptic or obovate, apex rounded or acute, mucronulate, base attenuate, cuneate to broadly cuneate, margin crenate or entire, petiole 0.5-2.5(3.5) cm long. Capitula solitary or in lax corymbs, 1.5-2.5 cm long, pedicel 2-5(7) cm long, distally inflated. Phyllaries 5, purple tinged, 1.5-2.5 cm long. Disk flowers bisexual, 25- 30 per head or more, corolla tube campanulate, yellow or greenish to purplish, 5-lobed, lobes ovate to train- gular, stamens 5, anthers apical appendages acute. Style 2-branched, curvate. Cypsela 7-10 mm long, hispidulous, pappus 6-9 mm long. Fl. Apr.-Sept.

Distribution:Native to SW. United States, Mexico, West Indies, Central America, South America^{[1, 3]}. It is found naturalized in Guangdong Province, China.

Voucher specimens: China (中国), Guangdong (广东), Shenzhen (深圳), Baoan District (宝安区), Tiegang Reservoir (铁岗水库), on the plant nursery, abandoned land, roadside, alt. 40-50 m. 2015-05- 06, W. Y. Zhao, W. S. Yang, J. Sun SZ-1-1746 (SYS), 2017-07-27, B. H. Wu PP2017451 to PP2017480 (CANT).

Usage: It is reported to be used as traditional medicine and pesticide^[6-7].

Discussion:Porophyllum ruderale grows well in the area of Tiegang Reservoir, with a large quantity of fruiting individuals and seedlings. It mainly grows in the abandoned place and ornamental plant nursery and can adapt to different intensity of illumination. Poro- phyllum ruderale was once cultivated in Hong Kong bordering on Shenzhen City^[5]. Taking into account the close relationship between the two cities, especially the active nursery stock transaction, it may be reason- able to infer that the population in Tiegang Reservoir seems to be introduced from Hong Kong with the nursery stock production, such as plant seeds or seedlings. Porophyllum ruderale is a kind of potential invasiveness herbs with high risk^[8]. It's a common invasive weeds in Brasil^[9-10]. It can adapt to many soil types^[7] and can even form thickets in the native range^[8]. In the past 50 years, this herb has spread out of the Americas, it was recorded naturalized in Hawaii^[11], Indonesia^[12] and Singapore^[13], and a variety of this species, P. ruderale var. macrocephalum (de Candolle) Cronquist was recorded naturalized in Galapagos Islands^[14]. It's appearance in Guangdong must be brought to the attention of the agricultural and forestry researchers and managers. It would be better to give the necessary monitoring of its distribution and spread in Guangdong.