シモバシラは花穂を立ち上げ、整然と白色の小花が咲き並びます。冬は茎の周りに水がしみ出て霜柱のように氷結。「霜華」とも呼ばれます。
Collinsonia japonica has flower spikes that stand up and white small flowers bloom in neat rows. In winter, water seeps out around the stems and freezes like needle ice. It is also called “frost flower”.
【仮名】シモバシラ, ユキヨセソウ
【和名】霜柱, 雪寄草
【英名】Collinsonia japonica
【学名】Collinsonia japonica, Keiskea japonica
【誕生】08/ ??
【開花】09, 10月
【花色】White, Pink
シモバシラ
シモバシラの概要
シモバシラはシソ科の多年草です。本州の関東地方以西、四国、九州の太平洋側に分布し、山地の林内や渓流の周辺で自生。秋は花穂を立ち上げ、整然と白色の小花が咲き並びます。冬は茎の周りに水がしみ出て、霜柱のように氷結。それを氷の花に見立てて「霜華」とも呼ばれます。
シモバシラの名前
シモバシラの名前の由来は枯れた茎の地際に「霜柱」のような結晶ができるから。茎に寄せられた雪のようなので「雪寄草」とも呼ばれます。ラテン語の属名コリンソニアは17～18世紀の英国の植物学者ピーター・コリンソンへの献名。種小名ジャポニカは「日本の」という意味です。
シモバシラの姿形
シモバシラの茎は４稜で、下方が直立し、上方が分枝します。葉は先の尖った長楕円形で柔らかく、縁に鋸歯があり、対生。花は穂状に咲き上がり、小花が横向きに並びます。小花は釣鐘状の唇形で、上唇が２裂、下唇が３裂、長く突き出た雄しべが４本。花後は丸い分果を結びます。
シモバシラの霜柱
シモバシラは冬になり、茎が立ち枯れるものの、根が地中の水分を吸収。茎に送り込まれた水分が、枯れた茎の外にしみ出します。その水が氷点下の外気に触れて凍結。つまり、地中の水分が地表にしみ出し、無数の細かい柱の形に凍結する「霜柱」とは別の仕組み、形状の氷結です。
Collinsonia japonica
Collinsonia japonica is a perennial plant of the Lamiaceae family. It is distributed on the Pacific coast of Honshu from the Kanto region westward, Shikoku, and Kyushu, and grows wild in mountain forests and around streams. In autumn, the flower spikes stand up and white small flowers bloom in neat rows. In winter, water seeps out around the stems and freezes like needle ice. It is also called “frost flower” because it resembles ice flowers.
The Japanese name for Collinsonia japonica is “Needle ice”. This is because needle ice-like crystals form around the ground of dead stems. It is also called “grass that looks like snow gathered together”. The Latin genus name Collinsonia is a tribute to the 17th-18th century English botanist Peter Collinson. The specific name japonica means “Japanese”.
The stem of Collinsonia japonica is four-sided, erect at the bottom and branched at the top. The leaves are soft, oblong with pointed tips, with serrated edges, and grow opposite each other. The flowers bloom in spikes, with florets arranged horizontally. The florets are bell-shaped with a lip, two lobes on the upper lip, three lobes on the lower lip, and four long, protruding stamens. After flowering, they produce round caryopsis.
In winter, the stems of Collinsonia japonica die, but the roots absorb moisture from the ground. The moisture pumped into the stems seeps out of the dead stems. When the water comes into contact with the freezing air, it freezes. In other words, this is a different mechanism and form of freezing from “needle ice,” in which moisture underground seeps to the surface and freezes into countless tiny pillars.
