Lemna valdiviana Phil., Linnaea.

Freitas, Rafaelle Neves, Silva, Maria Francilene Souza, Paiva, Jousimar Silva, Mayo, Simon Joseph & de Andrade, Ivanilza Moreira, 2017, Taxonomic survey of the Araceae Juss. in the coastal region of Piauí state, northeast Brazil, including the Rio Parnaíba Delta, Iheringia, Série Botânica 72 (3), pp. 341-350 : 343-344

2. Lemna valdiviana Phil., Linnaea. 33:239.1864. ( Figs. 1 D-G, 2B)

Minute, free-floating aquatic plant. Root one per frond, 0.5-4.3 cm long, surrounded at the base by a non-winged root sheath. Fronds 1.5-3 × 0.8-2 mm, sessile, in groups of 4-5, oblong-ovate to elongated, floating or slightly submerged below the water surface, shiny medium green on both sides, thin, glabrous, apex rounded, base narrower and asymmetrical, margins entire; one papilla present on the midline of the upper side; veins solitary, central, extending from the node to near frond apex. Flowers lateral, ovary ca. 1 mm long, unilocular, uniovular. Fruit ca. 0.5 mm long, green, style persistent. Seed ca. 0.3 mm long, brown with longitudinal ribs.

Phenology: Flowering and fruiting mainly from December to April.

Selected material: Parnaíba: Fazendinha, 09.IX.2011, Freitas 30 ( HDELTA) .

Comments: Lemna valdiviana was found in an environment in the presence of garbage and animal faeces. The single central vein on the frond differentiates it from L. aequinoctialis , which possesses three. The two species can be found in the same place and can easily be confused, but the difference in frond venation, and morphology of the sheath at the root base (winged in L. aequinoctialis and non-winged in L. valdiviana ) separates them. L. valdiviana has a high protein content and is considered promising as a food supplement for fish, aside from being able to play the role of phytoremediator, decontaminating or filtering polluted environments ( França et al. 2009).

It occurs in the Americas (North, Central and South, WCSP 2015). In Brazil, it occurs in the North (Amazonas), Northeast (Bahia, Paraiba, Pernambuco, Piauí), Midwest (Mato Grosso do Sul, Mato Grosso), Southeast (Rio de Janeiro) and South (Paraná, Rio Grande do Sul, Santa Catarina) ( Coelho et al. 2015).

Figures

Figs. 1A-S. Araceae from the coastal region of Piauí.A-C. Lemna aequinoctialis Welw.; A. Habit,side view; B. Habit, seen from above;C. Frond showing three veins; D-G. Lemna valdiviana Phil. D. Habit, side view; E. Habit, seen from above; F. Frond showing single vein; G. Fruit; H-N. Montrichardia linifera (Arruda) Schott. H. Habit; I. Inflorescence; J. Stamen; K. Stigma see from above; L. Female flower in longitudinal section showing ovule; M. Infructescence; N. Seed; O-S. Pistia stratiotes L. O. Habit; P. Leaf blade seen from above showing venation; Q. Inflorescence; R. Fruit; S. Seed.