ナガバミズアオイは真っ直ぐ立ち上がった花茎の先端に多数の小花を穂状に展開。小花は花弁６枚のうち、上１枚に黄緑色の模様が入ります。
Pickerelweed has a large number of small flowers blooming in spikes at the tip of a straight flower stalk. The florets have a yellow-green pattern on the upper one of the six petals.
【仮名】ナガバミズアオイ
【和名】長葉水葵
【英名】Pickerelweed
【学名】Pontederia cordata
【誕生】07/ 04
【開花】06, 07, 08, 09, 10月
【花色】Violet, Blue
ナガバミズアオイ
ナガバミズアオイの生態
ナガバミズアオイはミズアオイ科ポンテデリア属の水生多年草です。原産地は北米～南米で日当たりのよい湿地に自生。泥中を根茎が伸びて株も殖えるので、泥の表面が凍っても下まで凍らなければ枯れませんが、冬の寒さに弱いため、日本では関東近辺が野外で栽培できる北限です。
ナガバミズアオイの名前
ナガバミズアオイの名前の由来は、水生で葉柄が長く、葉の形がウマノスズクサ科の「寒葵」に似ているから。英名のピカーレルは淡水魚の「カワカマス」のことです。群生して産卵に適した茂みを作るから。属名は18世紀のイタリアの植物学者ジュリオ・ポンテデーラへの献名です。
ナガバミズアオイの葉
ナガバミズアオイは葉柄が根から直に生え、葉が細長いハート形です。種名のコルダタもラテン語で「心臓」を意味し、葉の形に由来。近縁種に葉幅の広い「丸長葉水葵」と、葉幅の狭い「細長葉水葵」があるものの、葉幅のほかに違いがないため、すべて同種とする見方もあります。
ナガバミズアオイの花
ナガバミズアオイは真っ直ぐ立ち上がった花茎の先端に多数の小花を穂状に展開。小花は花弁６枚のうち、上１枚に黄緑色の模様が入ります。花後は蒴果を結び、実生でも増殖。茎葉がスポンジ状で浮力はあるものの、湛水でも根が土を掴むので、「布袋葵」のようには浮遊しません。
Pickerelweed
Ecology of Pickerelweed
Pickerelweed is an aquatic perennial plant belonging to the genus Pontederia in the family Pontederiaceae. They are native to North and South America and grow naturally in sunny wetlands. The rhizomes grow in the mud and the plant propagates, so even if the surface of the mud freezes, they will not die unless it freezes to the bottom. But they are vulnerable to the cold of winter, so the Kanto area is the northern limit for their outdoor cultivation in Japan.
Name of Pickerelweed
The origin of the Japanese name of Pickerelweed is that it is aquatic and has long petioles, and the shape of the leaves resembles that of Asarum nipponicum of Aristolochiaceae. The English name Pickerel is a freshwater fish called “Pike”. Because they grow in clumps and create thickets suitable for spawning. The genus name is a dedication to Giulio Pontedera, an 18th-century Italian botanist.
Leaves of Pickerelweed
The leaf of Pickerelweed stalk grows directly from the root, and the leaf is long and heart-shaped. The species name cordata also means “heart” in Latin and is derived from the shape of the leaves. Although closely related species include the wide-leafed “Round-leaved Pickerelweed” and the narrow-leafed “Thin-leaved Pickerelweed”, there is no difference other than the leaf width, so there is a view that they are all the same species.
Flowers of Pickerelweed
Pickerelweed has a large number of small flowers at the tip of a straight flower stalk. The small flower has a yellow-green pattern on the upper one of the six petals. After flowering, they produce capsules and propagates in seedlings. Although the stems and leaves are spongy and have buoyancy, they do not float like “Water hyacinth” because their roots grip the soil even when flooded.
