出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2015/11/13 04:15:47」(JST)
サトイモ科 | |||||||||||||||
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アンスリウム(Anthurium andraeanum)
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分類(APG III) | |||||||||||||||
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学名 | |||||||||||||||
Araceae Juss.[2] | |||||||||||||||
タイプ属 | |||||||||||||||
Arum L.[2] | |||||||||||||||
シノニム | |||||||||||||||
Lemnaceae Martinov [2] |
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属 | |||||||||||||||
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サトイモ科 (Araceae) は、オモダカ目を構成する科の一つである。温暖で湿潤な環境を好み、湿地や沼地に生育するものも多い。花軸に密集した小さな花(肉穂花序)と、それを囲むように発達した苞(仏炎苞)が特徴。
サトイモやコンニャクなど、食品として重要なものも多いが、美しい葉や花を観賞するために栽培される種も多い。
新エングラー体系及びクロンキスト体系ではサトイモ目に分類されていた[3]。
サトイモ科の植物は、花に大きな特徴がある。花そのものは小さく、花びらがあっても目立たず、花びらがない場合もある。雄花と雌花に分かれているものもあり、いずれにしても、個々の花は小さく、目立たない。花は肉質の太い柄の上に一面に並んでつき、肉穂花序(にくすいかじょ)と呼ばれる。花は穂全体に着くものが多いが、穂の先端に花のない部分(付属体)があって、さまざまな形になるものもある。
穂の根元からは苞が出る。サトイモ科の植物では、多くの場合、苞が単純な葉の形ではなく、花の穂を包むような形になって、特別な色を持ち、目立つものが多い。言わば、花びらの役割を担っている。このような苞を仏炎苞(ぶつえんほう)と呼ぶ。仏炎苞の袋状の部分を筒部、筒部の上部で長い舌のように伸びる部分を舷部と呼ぶ。
このような構造を取る理由としては、花に寄ってくる昆虫を内部に閉じ込めることで、滞在時間を長くして受粉の確率を高めていると考えられる。
なお、東南アジア産のコンニャクの一種、ショクダイオオコンニャク(Amorphophallus titanium)は、花序の先端までが3mにも達し、花序としては世界で一番背が高いと言われる。
ショクダイオオコンニャクの花序・全景
同・花の部分を示す
上半分が雄花、下半分が雌花
ボタンウキクサの花序
サトイモ科の植物は、単子葉植物としては例外的に、葉の幅が広く、切れ込みがあったり、複葉になったりと、複雑な形のものがあり、葉脈も網状になったものが多い。どちらかと言えば、湿ったところに生育するものが多く、湿地性や半水性のものもある。日本では、地下に芋状の地下茎を持つものがよく見られるが、亜熱帯-熱帯では大型のつる植物になり、根を伸ばして樹木の幹に張りつき、よじ登るものがある。
なお、ウキクサ亜科とボタンウキクサは浮遊性の水草である。
サトイモ科の植物には、サトイモ(里芋=タロイモ)をはじめ、主食として用いられるものがある。特に東南アジアから太平洋にかけて、芋食文化が広がり、日本はその最北端に当たる。また、コンニャクも加工して食品となる。
また、熱帯地方のものには、葉の形の面白いものがあり、観葉植物として利用される。
日本では、ミズバショウやザゼンソウは北日本の季節の花として有名で、ミズバショウは「夏の思い出」などの歌にも出てくる。テンナンショウ類にも鑑賞価値の高いものがあり、その一部に野生では絶滅に瀕しているものがある。
一方、テンナンショウ属を始め、クワズイモ、ザゼンソウや多くの観用植物は有毒植物であり、シュウ酸カルシウムなどのシュウ酸塩を根茎などに含んでいる。
ショウブ属(Acorus)は葉が細長く平行脈で典型的な仏炎苞もないので、クロンキスト体系ではショウブ科(Acoraceae)、APG IIでは更にショウブ目(Acorales)として分ける。ウキクサ亜科はかつてウキクサ科として分離されていた。
8亜科が属する[4]。
次のような系統樹が得られている[4]。
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ウィキメディア・コモンズには、サトイモ科に関連するカテゴリがあります。 |
Araceae Temporal range: 70–0 Ma PreЄ
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Flower of Xanthosoma sagittifolium | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Angiosperms |
Clade: | Monocots |
Order: | Alismatales |
Family: | Araceae Juss.[2] |
Genera | |
Main article: List of Araceae genera
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The Araceae are a family of monocotyledonous flowering plants in which flowers are borne on a type of inflorescence called a spadix. The spadix is usually accompanied by, and sometimes partially enclosed in, a spathe or leaf-like bract. Also known as the arum family, members are often colloquially known as aroids. This family of 107 genera and over 3700 species is most diverse in the New World tropics, although also distributed in the Old World tropics and northern temperate regions. A comprehensive genomic study of Spirodela polyrhiza was published in February 2014.[3]
The largest collection of living Araceae is maintained at Missouri Botanical Gardens.[4] Another large collection of living Araceae can be found at Munich Botanical Garden, due to the efforts of researcher and aroid authority Josef Bogner.
Species in Araceae are often rhizomatous or tuberous and are often found to contain calcium oxalate crystals or raphides.[5][6] The leaves can vary considerably from species to species. The inflorescence is composed of a spadix, which is almost always surrounded by a modified leaf called a spathe.[7] In monoecious aroids (possessing separate male and female flowers, but with both flowers present on one plant), the spadix is usually organized with female flowers towards the bottom and male flowers towards the top. In aroids with perfect flowers, the stigma is no longer receptive when the pollen is released, thus preventing self-fertilization. Some species are dioecious.[8]
Many plants in this family are thermogenic (heat-producing).[9] Their flowers can reach up to 45°C even when the surrounding air temperature is much lower. One reason for this unusually high temperature is to attract insects (usually beetles) to pollinate the plant, rewarding the beetles with heat energy. Another reason is to prevent tissue damage in cold regions. Some examples of thermogenic Araceae are: Symplocarpus foetidus (eastern skunk cabbage), Amorphophallus titanum (titan arum), Amorphophallus paeoniifolius (elephant foot yam), Helicodiceros muscivorus (dead horse arum lily) and Sauromatum venosum (voodoo lily). Species such as titan arum and the dead horse arum give off a very pungent smell, often resembling a rotten animal, to attract flies to pollinate the plant. The heat produced by the plant helps to convey the scent further.
One of the earliest observations of species in Araceae was conducted by Theophrastus in his work Enquiry into Plants.[10] The Araceae were not recognized as a distinct group of plants until the 16th century. In 1789, Antoine Laurent de Jussieu classified all climbing aroids as Pothos and all terrestrial aroids as either Arum or Dracontium in his book Familles des Plantes.[citation needed]
The first major system of classification for the family was produced by Heinrich Wilhelm Schott, who published Genera Aroidearum in 1858 and Prodromus Systematis Aroidearum in 1860. Schott's system was based on floral characteristics, and used a narrow conception of a genus. Adolf Engler produced a classification in 1876, which was steadily refined up to 1920. His system is significantly different from Schott's, being based more on vegetative characters and anatomy. The two systems were to some extent rivals, with Engler's having more adherents before the advent of molecular phylogenetics brought new approaches.[11]
Modern studies based on gene sequences show the Araceae (including the Lemnoideae, duckweeds) to be monophyletic, and the first diverging group within the Alismatales.[12] The APG III system of 2009 recognizes the family, including the genera formerly segregated in the Lemnaceae.[13] The sinking of Lemnaceae into Araceae is not universally accepted. For example, the 2010 New Flora of the British Isles uses a paraphyletic Araceae and a separate Lemnaceae.[14]
Anthurium and Zantedeschia are two well-known members of this family, as are Colocasia esculenta (taro) and Xanthosoma roseum (elephant ear or ‘ape). The largest unbranched inflorescence in the world is that of the arum Amorphophallus titanum (titan arum).[15] The family includes many ornamental plants: Dieffenbachia, Aglaonema, Caladium, Nephthytis, and Epipremnum, to name a few. In the genus Cryptocoryne are many popular aquarium plants.[16] Both Colocasia esculenta (taro) and Monstera deliciosa provide food value; the fruit of M. deliciosa is called "Mexican breadfruit". Philodendron is an important plant in the ecosystems of the rainforests and is often used in home and interior decorating. Symplocarpus foetidus (skunk cabbage) is a common eastern North American species. An interesting peculiarity is that this family includes the largest unbranched inflorescence, that of the titan arum,[15] often erroneously called the "largest flower" and the smallest flowering plant and smallest fruit, found in the duckweed, Wolffia.[17]
Within the Aracae, genera such as Alocasia, Arisaema, Caladium, Colocasia, Dieffenbachia, and Philodendron contain calcium oxalate crystals in the form of raphides. When consumed, these may cause edema, vesicle formation, and dysphagia accompanied by painful stinging and burning to the mouth and throat, with the symptoms occurring for up to two weeks.[18]
List of foliage plant diseases (Araceae)
Wikimedia Commons has media related to Araceae. |
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リンク元 | 「Colocasia」「サトイモ科」 |
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