Commelina obliqua Vahl, Enum. Pl. 2: 172. 1806.

Pellegrini, Marco Octavio de Oliveira & Forzza, Rafaela Campostrini, 2017, Synopsis of Commelina L. (Commelinaceae) in the state of Rio de Janeiro, reveals a new white-flowered species endemic to Brazil, PhytoKeys 78, pp. 59-81 : 65

5. Commelina obliqua Vahl, Enum. Pl. 2: 172. 1806. Fig. 1E-G

Lectotype

(designated by Hunt 1994). s.loc., cultivated in France, ex horto Celsii, Ventenat s.n. (C barcode C10009563!).

Selected specimens seen.

BRAZIL. Rio de Janeiro: Guapimirim, trilha das Andorinhas, 20 Dec 1995, J.A. Lira Neto 145 (RB). Itatiaia, Parque Nacional do Itatiaia, parte baixa, atrás da casa do pesquisador, 21 Jan 2012, M.O.O. Pellegrini & L.S. Sylvestre 188 (RB). Nova Friburgo, Macaé de Cima, Reserva Ecológica Municipal de Macaé de Cima, estrada de terra próximo ao Hotel São João, 19 Jan 1999, J. Anderson et al. 9912 (UEC). Nova Iguaçu, Serra do Tinguá, Reserva Biológica do Tinguá, 13 May 1943, Guerra s.n. (NY 498159). Paraty, Fazenda São Lourenço, 17 Nov 1993, E. Martins s.n. (UEC 29410). Petrópolis, Quitandinha, Pedra do Quitandinha, 2 May 2010, M.O.O. Pellegrini 2 (RFA). Resende, margem da rodovia Dutra, Km 302 sentido RJ, ao lado da Light, próximo ao Rio Paraíba do Sul, 9 Jun 2012, M.O.O. Pellegrini et al. 231 (RB). Silva Jardim, 31 Jan 2015, L.S.B. Calazans 485 (RB). Teresópolis, Serra dos Órgãos, 26 Oct 1949, E. Pereira 635 (RB, US).

Distribution and habitat.

Mexico to Argentina being very common in shady disturbed areas such as road sides, gardens and forest margins, and in agricultural fields. It is less commonly found growing in drier regions and rocky outcrops (Fig. 2 ).

Phenology.

Throughout the year, but especially in the rainy season.

Conservation status.

Following the IUCN recommendations ( IUCN 2001), as currently circumscribed, C. obliqua should be considered as Least Concern (LC) in the state of Rio de Janeiro and worldwide.

Morphological notes.

A great deal of morphological variation can be observed in C. obliqua and in its current circumscription. It comprises plants from small to large stature (sometimes more than a 1.5 m high); stems from creeping with ascending apex to erect to sub-scandent, and thin and fibrous to robust and somewhat succulent stems. The leaves can vary from 4-20 cm long, from glabrous to scabrous to pilose, and from green to dark green to vinaceous abaxially. Flower size and color also vary, which as in C. erecta seems to be environmentally influenced, probably by differences in soil pH and light intensity (Pellegrini, pers. obs.). The petals of C. obliqua can range from intense blue to light blue, sometimes varying from lilac to pale lilac. Commelina obliqua likely represents a species complex and biosystematic studies are necessary in order to better understand and elucidate its boundaries. Until this is addressed we believe that a wide circumscription, as presented here, is currently the best way to deal with this taxon.

Figures

Figure 1. Commelina in the state of Rio de Janeiro. A C. benghalensis L. B C. diffusa Burm. f. C-D C. erecta L.: C detail of the inflorescence showing aborted upper cincinnus D flower E-F C. obliqua Vahl: E detail of the inflorescence showing the two developed cincinni F flower G C. rufipes var. glabrata (D. R. Hunt) Faden & D. R. Hunt H-I C. rufipes var. rufipes Seub.: H detail of the leaf-sheaths, showing the hirsute rusty hairs I mature fruits. G by Flora Virtual Estacion Biologica El Verde group, remaining field photos by M. O. O. Pellegrini.

Figure 2. Distribution map of Commelina in the state of Rio de Janeiro. Crosses C. benghalensis green dots C. diffusa var. diffusa; blue dots C. erecta; stars C. obliqua; empty square C. rufipes var. glabrata; full squares C. rufipes var. rufipes.