Pittosporum tobira - Pittosporum tobira

A large evergreen shrub of the Pittoberaceae family (APG classification: Pittoberaceae). It grows to a height of about 3 meters. The leaves grow densely alternately near the ends of the branches, are elliptical obovate, 10 cm long, 3 cm wide, leathery and shiny, and have rounded tips. In June, cymes are produced at the ends of the branches, and white flowers bloom. The flowers are unisexual, fragrant, and dioecious. There are five sepals, which are ovate and have hairy edges. The petals are spatula-shaped and open flat, and the tips are often curled back. The stamens of male flowers are long and fertile, but those of female flowers are small and sterile. Each female flower has one pistil consisting of three carpels. The fruit is spherical, 1.2 to 1.6 cm in diameter, and opens in three when ripe, exposing red seeds. The name comes from the practice of placing the fruit on doors on Setsubun as a talisman, and it is also known as Tobira no Ki. It grows on the coast and is found in the Kanto region and west of Honshu, Okinawa, the southern part of the Korean Peninsula, southern mainland China, and Taiwan, but it may not be native to China.

The closely related Koyasunoki (children's tree) P. illicioides Makino is an evergreen shrub. The leaves are not as thick as Pittosporum tobira and have sharp tips. The flower stalks are hairless and slender. They grow in the forests of the mountains of Hyogo and Okayama prefectures, and are also found in Taiwan and central mainland China. They are often found in the forests of shrines, and are named Koyasunoki because they are used to pray for safe childbirth.

There are about 150 species in the genus Pittosporum, some of which are found in Asia, but the main distribution is in Polynesia and Australia. There are four closely related species of Pittosporum in the Ogasawara Islands, and it is known that significant speciation has occurred in a small area.

[Kyoshio Furusawa November 17, 2021]

The Pittosporaceae family is also classified as Pittosporaceae in the APG classification. According to this classification, there are about 250 species in nine genera found in the warm to tropical regions of Asia, Africa, and Australia, and one genus with six species is found in Japan.

[Editorial Department, November 17, 2021]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

トベラ科（APG分類：トベラ科）の常緑の大形低木。高さ約3メートルに達する。葉は枝先近くに密に互生し、楕円(だえん)状倒卵形で長さ10センチメートル、幅約3センチメートル、革質で光沢があり、先は丸い。6月ころ、枝先に集散花序をつくり、白色花を開く。花は単性花で芳香があり、雌雄異株。萼片(がくへん)は5枚、卵形で縁(へり)に毛がある。花弁はへら形で平開し、先端はしばしば反り返る。雄しべは雄花では長く稔性(ねんせい)であるが、雌花では小さく不稔性。雌花には3枚の心皮からなる雌しべが1本ある。果実は球形で、径1.2～1.6センチメートル、熟すと3裂開し、赤色の種子を裸出する。名は、節分に、この果実を扉に挟み、魔除(まよ)けとすることに由来し、別名トビラノキともいう。海岸に生え、関東地方以西の本州から沖縄、および朝鮮半島南部、中国大陸南部、台湾に分布するが中国のものは自生ではない可能性がある。

　近縁のコヤスノキ（子安木）P. illicioides Makinoは常緑低木。葉質はトベラほど厚くなく、先は鋭くとがる。花柄は毛がなく、細長い。兵庫県、岡山県の山地の林内に生え、台湾と中国大陸中部にも分布する。神社の林に多くみられ、安産祈願をすることからコヤスノキの名がある。

　トベラ属は約150種あり、一部はアジアにあるが、分布の中心はポリネシアおよびオーストラリアである。小笠原(おがさわら)にはトベラの近縁種が4種あり、狭い地域で著しく種分化がおこっていることで知られる。

［古澤潔夫　2021年11月17日］

　トベラ科PittosporaceaeはAPG分類でもトベラ科とされる。この分類によるとアジア、アフリカ、オーストラリアの暖帯から熱帯に9属約250種あり、日本には1属6種が分布する。

［編集部　2021年11月17日］

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