かっこそう (勝紅草) [Index] [Back] わが国の群馬県、桐生市・みどり市の狭い地域だけに分布しています。山地いある落葉樹林の林床に生え、高さは１０〜２０センチになります。葉は広円形で、縁は掌状に浅く不規則に切れ込み、さらに細かい歯牙があります。また葉は厚くて、表面の葉脈がくぼんで著しいしわとなります。５月ごろ、茎頂に５〜１５個の花を、やや輪生状で１〜３段に咲かせます。花冠は紅紫色で高杯状、先端は５裂して広く開き、裂片の先がさらに２裂します。本種も異形花柱花で、短花柱花と長花柱花の２タイプの花があります。これは違うタイプの花同士で交配しやすく、同じタイプの花同士では交配しにくいという性質に繋がります。この交配を媒介しているのはトラマルハナバチやビロードツリアブといった昆虫だと考えられています。別名で「きそこざくら（木曽小桜）」と呼ばれますが、長野県木曽地方での分布は確認されていません。環境省レッドリストでは、絶滅危惧IA類 (CR) に分類されています。 サクラソウ科サクラソウ属の多年草で、学名は Primula kisoana。英名はありません。 The "Kakko-so" (Primula kisoana) belongs to Primulaceae (the Primrose family). It is a perennial herb that is found exclusively in the narrow region of Gunma Prefecture, specifically in the cities of Kiryu and Midori. It grows in the forest floor of deciduous forests in mountainous areas, reaching a height of 10 to 20 cm. The leaves are broadly rounded, with the edges shallowly and irregularly lobed in palmately, and further adorned with fine teeth. The leaves are thick, with prominent veins on the surface forming distinct wrinkles. Around May, 5 to 15 flowers bloom in 1 to 3 whorls at the top of the stem. The corolla is reddish purple, cup-shaped, with 5 lobes that open widely at the tip, and the tips of the lobes are further divided into 2 lobes. This species also has heterostylous flowers, with two types of flowers: short-style flowers and long-style flowers. This trait makes it easier for flowers of different types to cross-pollinate, while flowers of the same type are less likely to cross-pollinate. It is believed that insects such as the Bombus diversus and the Bombylius major act as pollinators. It is also known by the common name "Kiso-kozakura", but its distribution in the Kiso region of Nagano Prefecture has not been confirmed. It is classified as Critically Endangered (CR) on the Ministry of the Environment's Red List. 山形市神尾「山形市野草園」にて、2025年05月11日撮影。 Shu Suehiro shu@botanic.jp