noun
Phyllospadix iwatensis (a species of seagrass)
A specific marine plant native to coastal waters around Japan; the name is typically written in katakana in field guides and everyday use.
スガモは北海道から九州の沿岸で見られる海草です。
Sugamo is a seagrass found along the coasts from Hokkaido to Kyushu.
このあたりの海底にはスガモが一面に生えている。
The seabed around here is covered with sugamo.
The name likely derives from the plant's resemblance to sedge (菅, すげ) and its aquatic nature (藻, も), but the exact origin is uncertain.