出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/12/26 11:52:46」(JST)
| ツユクサ科 | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
ツユクサ（Commelina communis）
|
||||||||||||||||||
| 分類 | ||||||||||||||||||
|
||||||||||||||||||
| 属 | ||||||||||||||||||
|
ツユクサ科(Commelinaceae)は単子葉植物に属する科で、ツユクサ目を構成する5科の中では最大の約40属650種を含む。[1] ムラサキツユクサ、ムラサキオモト等の園芸植物の他、日本にはツユクサ、イボクサ、ヤブミョウガなどが自生する。ツユクサ科は旧熱帯・新熱帯の両方で多様性が高く、両方に分布する属もある。[2] 花や花序を初めとした形態が被子植物の中でも特に変異に富むとされる。[3][4]
ツユクサ科という枠組みは長きにわたって分類学者に認められ続けている。APG体系でも、1998年のAPGIから現行の2009年のAPGIIIに至るまで認められ続けており、単子葉類のツユクサ類ツユクサ目に位置付けられている。ツユクサ科の植物は草本で、茎はよく発達し、しばしば節に膨らみを持つ。多くの場合1つ1つの花は短命で、開花から1日と持たずにしぼんでしまう。
ツユクサ科の花は前述の通り短命で、蜜腺を欠き、送粉者に対する報酬は花粉のみである。性表現の面では、両性または雄性両全性同株であるが、Callisia属には雌性両全性同株の種がある。このような性的多型の具体例には、小花梗の長さ、花糸の長さ及び曲がり具合、雄しべの数及び位置などがある。環境によって多少なりとも影響を受けるものの、多くの種では開花期や開花時刻がある程度決まっていて、生殖隔離に関わっていると考えられている他、雄花と両性花の開花時刻に差異がある例もある。ツユクサ科の花には実際より多くの報酬があると送粉者を誤認させる仕組みをもつ傾向がある。例えば、花粉に似せた黄色い毛や広い葯隔、成熟花粉を作らない仮雄しべなどがある。[5]
ツユクサ科の植物は多年生が多いが、一年生の種もある。着生植物のCochliostemaを除いて地上性である。典型的には直立するか、這って斜上し、しばしば節から発根したり匍匐茎を伸ばして無性的に繁殖する。根茎をもつものもあり、アオイカズラ属Streptolirion、Aetheolirion、一部のSpatholirionはつる性でよじ登る。根はひげ根か塊根になる。[1]
葉の基部は葉鞘になって茎を取りまく。イネ科も葉鞘を持つことで知られるが、ツユクサ科の方は葉鞘が閉じ、葉舌を持たない点で異なる。葉は互生し、中には2列生や螺生が見られる。葉は単葉で全縁(鋸歯や切れ込みを持たない)、しばしば多肉気味で、基部で狭くなるものがある。ツユクサ科の特徴の1つに、芽内姿勢が内巻きであることがあげられる。即ち、葉の葉の両縁が向軸側で中軸にむかって巻き込む。しかし、複数の葉またはそれぞれの葉が片巻になって出るグループも知られている。[1]
花序は頂芽または腋芽として形成され、Coleotrypeやヤンバルミョウガ属Amischotolypeなど腋芽が葉鞘を貫通する種も稀にある。花序は蠍状花序によって構成される密穂花序であるが、蠍状花序の基本構造には大きな変更や短縮が見られることがある。花序や小花序は総苞に苞に包まれていることがある。[1]
花は放射相称または左右相称である。それぞれの花が咲いている時間は短く、花弁は開花後数時間で溶けてしまうことが多い。両性花のみを持つ種が多いが、雄性両全性同株も少なくなく、Callisia repensは雌性両全性同株であり、雄性雌性両全性同株の種もある。萼片は3つで、同形または異形、合着は基部で見られるか全くなく、緑色または花弁様である。同様に花弁は3つで、同形または二型が見られ、基部で合着するか離生し、白または有色である。花弁は基部で細長くなっている、即ち爪部を持つことがある。雄しべは基本的に6本で2輪生だが、3本だけの場合もある。雄蕊の形態や配置は実に多様である。全てが稔性を持つ完全雄蕊である場合は、それらが全て同形の種と異形の完全雄蕊を持つ種がある。一方で、多くの属では2つか4つ、不稔の仮雄蕊がある。仮雄蕊は完全雄蕊と交互に配列することもあれば、上半分または下半分に集中することもある。花糸は多くの属で有毛だが、有毛と無毛が混じることもある。花粉はしばしば葯の側方が縦裂して放出されるが、先端で孔開して放出される場合もある。[1]
| この項目は、植物に関連した書きかけの項目です。この項目を加筆・訂正などしてくださる協力者を求めています（プロジェクト:植物／Portal:植物）。 |
| Commelinaceae | |
|---|---|
| Aneilema aequinoctiale | |
| Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Clade: | Commelinids |
| Order: | Commelinales |
| Family: | Commelinaceae Mirb.[1] |
| Genera | |
|
see List of Commelinaceae genera |
|
Commelinaceae is a family of flowering plants. In less formal contexts, the group is referred to as the dayflower family or spiderwort family. It is one of five families in the order Commelinales and by far the largest of these with about 731 known species in 41 genera.[2] Well known genera include Commelina (dayflowers) and Tradescantia (spiderworts). The family is diverse in both the Old World tropics and the New World tropics, with some genera present in both.[3] The variation in morphology, especially that of the flower and inflorescence, is considered to be exceptionally high amongst the angiosperms.[4][5]
The family has always been recognized by most taxonomists. The APG III system of 2009 (unchanged from the APG system of 1998), also recognizes this family, and assigns it to the order Commelinales in the clade commelinids in the monocots. The family counts several hundred species of herbaceous plants. Many are cultivated as ornamentals. The stems of these plants are generally well-developed, and often swollen at the nodes. Flowers are often short-lived, lasting for a day or less.
The flowers of Commelinaceae are ephemeral, lack nectar, and offer only pollen as a reward to their pollinators. Most species are hermaphroditic, meaning each flower contains male and female organs, or andromonoecious, meaning that both bisexual and male flowers occur on the same plant. Floral dimorphism may be accompanied by variable pedicel length, filament length and/or curvature, or stamen number and/or position. Species tend to have specific flowering seasons, though local environmental factors tend to effect exact timing, sometimes considerably. Species tend to flower at a specific time of day as well, with these periods being well defined enough to presumably isolate different species reproductively. Furthermore, some species exhibit differential opening times for male and bisexual flowers. Commelinaceae flowers tend to deceive pollinators by appearing to offer a larger reward than is actually present. This is accomplished with various adaptations such as yellow hairs or broad anther connectives that mimic pollen, or staminodes that lack pollen but appear like fertile stamens.[6]
Plants in the Commelinaceae are usually perennials, but a smaller number of species are annuals. They are always terrestrial except for plants in the genus Cochliostema, which are epiphytes. Plants typically have an erect or scrambling but ascending habit, often spreading by rooting at the nodes or by stolons. Some have rhizomes, and the genera Streptolirion, Aetheolirion, and some species of Spatholirion are climbers. The roots are either fibrous or form tubers.[7]
Leaves form sheaths at their bases that surround the stem, much like the leaves of grasses, except that the sheaths are closed and do not have a ligule. The leaves alternate up the stem and may be two-ranked or spirally arranged. The leaf blades are simple and entire (that is, they lack any teeth or lobes), they sometimes narrow at the base, and they are often succulent. The way in which the leaves typically unfurl from bud is a distinctive feature of the family: it is termed involute, and means that the margins at the leaf base are rolled in when they first emerge. However, some groups are supervolute or convolute.[7]
The inflorescences occur either as a terminal shoot at the top of the plant, or as terminal and axillary shoots arising from lower nodes, or rarely as only axillary shoots that pierce through the leaf sheath such as in Coleotrype and Amischotolype. The inflorescence is classed as a thyrse, and each subunit is made up of cincinni; this basically means that flowers are grouped in scorpion's tail-like clusters along a central axis, although this basic ground plan can become highly modified or reduced. Inflorescences or their subunit are sometimes enclosed in a leaf-like bract often called a spathe.[7]
Flowers can have either one or many planes of symmetry; that is either zygomorphic or actinomorphic. They remain open for only a few hours after opening, after which they deliquesce. The flowers are usually all bisexual (hermaphrodite), but some species have both male and bisexual flowers (andromonoecious), the single species Callisia repens has bisexual and female flowers (gynomonoecious), and some have bisexual, male, and female flowers (polygamomonoecious). nectaries are not found in any species within the family. There are always three sepals, although they may be equal or unequal, unfused or basally fused, petal-like or green. Likewise there are always three petals, but these may be equal or in two forms, free or basally fused, white or coloured. The petals are sometimes clawed, meaning they narrow to stalk at the base where they attach to the rest of the flower. There are almost always six stamens in two whorls, but these occur in a myriad of arrangements and forms. They may be all fertile and equal or unequal, but in many genera two to four are staminodes (i.e. infertile, non-pollen producing stamens). Staminodes can alternate with the fertile stamens or they can all occur in the upper or lower hemisphere of the flower. The stalks of the stamens are bearded in many genera, although in some of these only some are bearded while others are hairless. Sometimes one to three stamens are absent altogether. Pollen is usually released from slits that open on the sides of the anthers from top to bottom, but some species have pores that open at the tips.[7]
The Commelinaceae are a well supported monophyletic group according to the analysis of Burns. et al. (2011).[8] The following is a phylogeny, or evolutionary tree, of most of the genera in Commelinaceae based on DNA sequences from the plastid gene rbcL[9]
| Family Commelinaceae |
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
All clades shown have 80% bootstrap support or better.
| Wikimedia Commons has media related to Commelinaceae. |
| Wikispecies has information related to Commelinaceae |
| Taxon identifiers |
|
|---|
| リンク元 | 「Commelina」「ツユクサ科」 |