Lysimachia rupestris F. H. Chen & C. M. Hu 1979

Lysimachia rupestris F. H. Chen & C. M. Hu (Fig. 1) In Acta Phytotaxonomica Sinica 17 (4): 40 (1979). SPECIMEN DATA. — Vietnam. Ha Long Bay, Quang Ninh, 20°48’6.56”N, 106°59’40.51”E, alt. 163 m, on rocks at the top of limestone hills, 29.IV.2015, Nian He Xia, Viet Lam Le & Duy Hung Vuong, s.n . (IBSC, two duplicates). DESCRIPTION Herbs perennial, 2-5 cm tall, glabrous throughout. Stems copiously minutely glandular; stolons 2- many, 6-17 cm long, arising from leaf rosette, leafy at apex. Leaves spirally arranged, ± forming a rosette; petiole 1-2 cm long, narrowly winged; leaf blade elliptic-oblanceolate, 3-6.5 × 1.2-2.2 cm, minutely glandular on both sides, base long attenuate, margin narrowly revolute, apex acute to obtuse; veins 3 or 4 pairs, prominent abaxially; veinlets invisible. Flowers solitary, axillary. Pedicel 2.5-4 cm long, densely minutely glandular. Calyx c. 1 cm long, divided to base, lobes lanceolate, c. 1 cm × 1.5-2 mm, densely minutely glandular, especially so at the base, with 1 midvein, reticulate veins inconspicuous. Corolla yellow, divided near to base, lobes oblong-lanceolate, 7-8 mm × c. 2 mm, apex acute to obtuse, glabrous. Stamens 5, filaments c. 1 mm long, connate basally into a ring, free parts c. 0.7 mm long; anthers 4-5 mm, basifixed, opening by apical pores. Style c. 6 mm long, glabrous; stigma punctate, ovary subglobose, glabrous. Capsule subglobose, c. 4 mm in diam. Flowering April-May, fruiting May-August. REMARKS Because of the similar vegetative appearance, Chen & Hu (1979) assigned Lysimachia rupestris together with L. alpestris Champ. ex Benth. to subgenus Lysimachia section Rosulatae R. Knuth only according to the flower characters of L. alpestris, i.e. the dorsifixed anthers opening by lateral slits, which is an important feature of subgenus Lysimachia, although it also has short filaments connate basally into a very short ring and does not bear colored glands, which are the features of subgenus Idiophyton Hand.-Mazz. Bennell & Hu (1983) suggested that subgenus Lysimachia section Rosulatae could be derived directly from subgenus Idiophyton section Apodanthera based on pollen morphology. Recent phylogenetic research confirmed that section Rosulatae is more close to subgenus Idiophyton, rather than subgenus Lysimachia (Hao et al. 2004; Anderberg et al. 2007). Our supplement of the floral characters, especially the basifixed anthers opening by apical pores (Fig. 1F) of L. rupestris is another strong evidence to support that section Rosulatae should be transferred to subgenus Idiophyton. The third species with the spirally aggregated leaves forming nearly rosettes is the recently described L. verbascifolia (Phan & Hu 2011). This species also has basifixed anthers opening by apical pores, which shows its affinity of L. rupestis. However, the lack of stolons in L. verbascifolia adds confusion to the relationship between these species. Thus, there is still much work to do to figure out their systematic position.