Sagittaria guayanensis Kunth

Global description

Sagittaria guayanensis is an aquatic herbaceous plant, with short rhizome, annual or vivacious, which can be erect or floating. Leaves, all arranged at the base, are either submerged, with linear blade, or floating (most) with oval blade deeply sagittate at the base. Flowers, white, are grouped by 3, and in whorls at the end of an upright stem exceeding the water. The fruit is a globular cluster carried by a bent stalk. It is immersed; maturation takes place under water. It is a group of akenes with backpack ornated with bumps arranged in rows.
 
General habit

Aquatic herbaceous plant, annual or vivacious, according to circumstances, which can be erect or floating.
 
Underground system

The underground system is a short rhizome with the roots sometimes forming a tuber.
 
Stem

The stem is erect, fleshy, cylindrical section. The greater part is under water. Only the upper part that bears the inflorescence emerges.
 
 
Leaf

All the leaves are arranged at the base. Submerged leaves are linear-lanceolate. Most of the leaves are floating with a long submerged stalk connecting them to the base of the plant. Their ovate blade (8 cm long and slightly less wide), is deeply sagittate at the base. It has a network of curved ribs which extend from the insertion of the stalk towards the front and towards the two posterior lobes.
 
Inflorescence

The upper part of the stem carries 1 to 5 whorls of 3 flowers (in general), located in the axil of a bract of 0.6 to 2 cm long and 3-8 mm wide.
 
Flower

The flowers can be bisexual or unisexual, either male or female. The male flowers have a right and slender stalk, 2 to 6 cm long. Bisexual and female flowers have a curved and thick pedicel, 1.5 to 4 cm long. The calyx has 3 free triangular sepals, 10 to 15 mm long, green in color. They remain applied to the fruit. The corolla, white, consists of three free petals, 12 to 18 mm long. The stamens (6 to 12) have a filament that can be smooth or glandular.
 
Fruit

The fruit is a globular cluster carried by a thick curved stalk. It is immersed and its maturation takes place under water. Each element is a round achene of 2.5 mm long at most, the back decorated with several lines of protuberances.

Origin

Sagittaria guayanensis is native to Tropical America

Worldwide distribution

It is now a pantropical species. In the Indian Ocean it is present in Madagascar but absent from the Comoros, Reunion and Mauritius, in Oceania it is absent from Australia and the Pacific Islands.

https://www.gbif.org/fr/species/5329055