Mitrastemon yamamotoi (English name)

Japanese: ヤッコソウ(奴草) - ヤッコソウ（英語表記）Mitrastemon yamamotoi

An annual parasitic plant of the Rafflesiaceae family. It is sometimes classified as a Miacanthopanax. It is endemic to Japan, growing in groups on the roots of Chinese linden trees in the southern subtropical regions of Shikoku and Kyushu, but is rare. It lacks chlorophyll and parasitises living organisms. It grows 5-7cm tall. It extends hyphae-like nutrient-intake organs into the roots of the host. Buds form in the host tissue and break through the host body. The thickened flower stalk stands upright, with scale leaves arranged in a cross pattern. The scale leaves gradually grow larger toward the top. In autumn, a single flower appears at the top of the upright stem. The perianth is fused into a tubular shape and remains persistent even after flowering. The stamens are also fused like a cap and encase the ovary. When they are removed, the pistil appears from below and is longer than the perianth. The ovary is one-lobed and bears many ovules on the lateral membrane placenta. The fruit is berry-like, and produces many small seeds with net patterns. The flowers contain nectar that attracts small birds. They are ornithophilous. The area where the flower grows in Hioki City, Kagoshima Prefecture, is protected as a national natural monument. The Rafflesiaceae family has about 12 genera and 60 species known worldwide, and is found mainly in the tropics and on the Malay Peninsula. Rafflesia is the most famous of these.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

ラフレシア科の一年生の寄生植物。ヤッコソウ科に分類されることもある。日本特産で，四国，九州など暖帯南部のシイノキの根に群れをなして生えるが，稀産である。葉緑素を欠き活物寄生をする。高さ5～7cm。宿主の根の中へ菌糸に似た栄養摂取器官を伸ばす。つぼみは宿主の組織中に生じ，宿主体を破って伸び出す。肥厚した花茎は直立し，鱗片葉が十字対生につく。鱗片葉は上部へいくにつれ徐々に大きくなる。秋，直立した茎頂に花を単生する。花被は筒形に合着し，花後も宿存する。おしべも帽子のように合着して子房を包み，これがはずれると下からめしべが現れ，花被より長くなる。子房は1室で側膜胎座に多数の胚珠をつける。果実は液果状で，網紋のある小型の種子が多数できる。花には蜜があり小鳥が吸いに来る。いわゆる鳥媒花である。鹿児島県日置市のヤッコソウ発生地は国の天然記念物として保護されている。ラフレシア科は世界に約 12属 60種が知られ，主として熱帯に分布し，マレー半島に産する。なかでもラフレシアは有名。

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