Sagittaria graminea

The name Grass-leaved arrowhead, Sagittaria graminea, is long known in the aquarium hobby and is also used for plants that are sold as marginal plants for water gardens. However, these plants do not belong to the species S. graminea as it is described in the Sagittaria revision by Keener (2005)¹ (see further below). They rather belong to Weatherby's arrowhead, Sagittaria weatherbiana in most cases. A plant with white variegated aerial leaves is known under the cultivar name S. graminea 'Crushed Ice' since about 2000. It is unknown to us whether this cultivar also belongs to S. weatherbiana.

According to the species description in Keener (2005), Sagittaria graminea may have a rhizome or corms but not stolons. The emersed leaf blades have a very narrow, linear to linear-oblanceolate shape (see photo). This plant is very likely not cultivated as aquarium plant and unavailable in trade (at least in Europe).

On the contrary, Sagittaria weatherbiana develops underground stolons, often with a corm at the tip, but not a rhizome. It has broad, strap-shaped submerged leaves (phyllodes), similar to S. platyphylla, and egg-shaped to lanceolate emersed leaves. There are probably further Sagittaria species cultivated under the name S. graminea.

In former times, several arrowhead taxa were counted among S. graminea that are now seen as distinct species, for example Sagittaria platyphylla, as S. graminea var. platyphylla, giving rise to some name confusion. Also S. weatherbiana und S. chapmanii are still treated as subspecies of S. graminea in the "Flora of North America"² (Sagittaria graminea subsp. weatherbiana and subsp. chapmanii). These are recognised as species by Keener (2005).

Sagittaria graminea in the narrower sense occurs in the eastern and southeastern USA and southeastern Canada. The perennial plants are up to about 100 cm tall. The leaves are phyllodial or divided into petiole and blade. The phyllodes are emersed oder submerged, flattened, linear, 6 to 10 cm long and 0,5 to 4 cm wide. The petiolate leaves are emersed, with 4 to 30 cm long petiole and linear to lanceolate blade that is 2 to 25 cm long and 0,2 to 4 cm wide. The scapes are erect, with 6 to 50 cm long peduncle. The inflorescences are 2 to 37 cm long, 1 to 6 cm wide racemes with 2 to 8 whorls. Each whorl has 2 to 3 flowers. The lower whorls bear female (pistillate), the upper whorls male (staminate) flowers.¹