Biology and Natural History of Sushi Grass

Though well known for its use as a garnish, the botanical origins, life history, and genetics of common sushi grass are poorly understood. This work attempts to shed light on some aspects of sushi grass biology to pave the way for future research on this agronomically important species.

Figure 1, Anatomy

A) The sushi grass leaf displays several unique anatomical features (bar represents 1 cm). The mode of Sushi grass reproduction remains obscure. Sushi grass is occasionally associated with flower-like structures (B), but these lack stamens or carpels and are, therefore, sterile.

Figure 2, Habitat

Sushi grass is widely distributed in North America with traditional ranges on both coasts and evidence for recent expansion in the south and Midwest. In terms of habitat, sushi grass appears equally adept at colonizing natural (A) and urban (B) landscapes.

Figure 3, Drought Tolerance

The ability to tolerate drought is a hallmark of the species. In side-by-side trials with controls (left) in which soil was allowed to dry over 72 hours, the resistance of sushi grass (right) to drought-induced wilting was impressive.

Figure 4, Chlorophyll Retention

Sushi grass is notable in its resistance to yellowing. Compared to a control leaf that displays noticeable chlorophyll loss 48 hours after removal from the plant (left), the sushi grass leaf (right) retains its bright green color despite complete detachment from any visible root system. This trial was continued for an additional three weeks with no visible change in sushi grass color (results not shown).

Figure 5, Genetics

Extraction of DNA from sushi grass proved difficult, possibly due to the resistance of the tissue to enzymatic and mechanical breakdown. However, approximately 0.01 picograms of DNA was obtained. Surprisingly, genome sequencing reveals that sushi grass is more closely related to Atlantic salmon (Salmo salar) than to the flowering plants or ferns. We acknowledge the possibility that our sushi grass sample was contaminated by foreign DNA; however, we cannot imagine conditions under which sushi grass would come into direct contact with fresh salmon tissue. If confirmed, these unexpected results bring long-held evolutionary assumptions into question.

Acknowledgements. This work was generously funded by a grant from the USDA (United Sushi Dining Association).