こあまも (小甘藻) [Index] [Back] わが国の各地をはじめ、台湾や朝鮮半島、中国東北部、ベトナムそれにロシアの極東地方に分布しています。主に水深１〜２メートルの浅海域の砂泥地や、一部汽水域でも生え、葉の長さは１０〜３０センチになります。地下茎を伸ばして、節から狭線形の葉をだします。葉の縁は全縁で、明瞭な２〜３個の平行脈があります。雌雄同株で、６月ごろ、節から花茎をだし、肉穂花序に花を咲かせます。雄花は花序の先端に、雌花は花序の中央につきます。水中媒の植物です。台湾華語では「甘藻」、中国語では「矮大葉藻（ai da ye zao）」と呼ばれます。 アマモ科アマモ属の多年草で、学名は Zostera japonica。英名は Japanese eelgrass、Dwarf eelgrass。 The Japanese eelgrass (Zostera japonica) belongs to the family Zosteraceae. It is a perennial herb that is distributed throughout Japan, as well as in Taiwan, the Korean Peninsula, northeastern China, Vietnam, and the Russian Far East. It grows primarily in sandy-muddy areas of shallow waters 1 to 2 m deep, and in some brackish water areas, with leaves ranging from 10 to 30 cm in length. It extends rhizomes and produces narrow-linear leaves from the nodes. The leaf margins are entire, with 2 to 3 distinct parallel veins. It is monoecious; around June, it produces flower stalks from the nodes, bearing flowers in a spicate inflorescence. Male flowers are located at the tips of the inflorescence, while female flowers are found in the center. It is a plant pollinated by Hydrogamy (submerged pollination). In Taiwanese Chinese, it is called "甘藻", and "矮大葉藻" (ai da ye zao) in Chinese. 茨城県つくば市「つくば実験植物園」にて、2026年03月07日撮影。 Shu Suehiro shu@botanic.jp