| Commelinaceae | |
|---|---|
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| Aneilema aequinoctiale | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Clade: | Commelinids |
| Order: | Commelinales |
| Family: | Commelinaceae Mirb.[1] |
| Genera | |
Commelinaceae is afamily offlowering plants. In less formal contexts, the group is referred to as thedayflower family orspiderwort family. It is one of five families in theorderCommelinales and by far the largest of these with about 731 known species in 41 genera.[2] Well known genera includeCommelina (dayflowers) andTradescantia (spiderworts). The family is diverse in both theOld World tropics and theNew World tropics, with some genera present in both.[3] The variation inmorphology, especially that of theflower andinflorescence, is considered to be exceptionally high amongst theangiosperms.[4][5]
The family has always been recognized by most taxonomists. TheAPG III system of 2009 (unchanged from theAPG system of 1998), also recognizes this family, and assigns it to the orderCommelinales in the cladecommelinids in themonocots. 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, lacknectar, and offer only pollen as a reward to their pollinators. Most species arehermaphroditic, meaning each flower contains male and female organs, or andromonoecious, meaning that both bisexual and male flowers occur on the same plant. Floraldimorphism may be accompanied by variablepedicel length,filament length and/or curvature, orstamen 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, orstaminodes that lack pollen but appear like fertile stamens.[6]
Plants in the Commelinaceae are usuallyperennials, but a smaller number of species areannuals. They are alwaysterrestrial except for plants in the genusCochliostema, which areepiphytes. Plants typically have an erect or scrambling but ascending habit, often spreading by rooting at thenodes or bystolons. Some haverhizomes, and the generaStreptolirion,Aetheolirion, and some species ofSpatholirion are climbers. The roots are either fibrous or formtubers.[7]
Leaves form sheaths at their bases that surround the stem, much like the leaves ofgrasses, except that the sheaths are closed and do not have aligule. 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 oftensucculent. The way in which the leaves typically unfurl from bud is a distinctive feature of the family: it is termedinvolute, and means that the margins at the leaf base are rolled in when they first emerge. However, some groups aresupervolute orconvolute.[7]
Theinflorescences occur either as a terminal shoot at the top of the plant, or as terminal and axillary shoots arising from lowernodes, or rarely as only axillary shoots that pierce through the leaf sheath such as inColeotrype andAmischotolype. The inflorescence is classed as athyrse, and each subunit is made up ofcincinni; 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-likebract often called aspathe.[7]
Flowers can have either one or many planes of symmetry; that is eitherzygomorphic oractinomorphic. They remain open for only a few hours after opening, after which theydeliquesce. The flowers are usually all bisexual (hermaphrodite), but some species have both male and bisexual flowers (andromonoecious), the single speciesCallisia 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 threesepals, 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 arestaminodes (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 theanthers from top to bottom, but some species have pores that open at the tips.[7]
The Commelinaceae is a well supported monophyletic group according to the analysis of Burnset al. (2011).[8] The following is aphylogeny, or evolutionary tree, of most of the genera in Commelinaceae based onDNA sequences from theplastid gene rbcL[9]
| Family Commelinaceae |
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Allclades shown have 80%bootstrap support or better.
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Media related toCommelinaceae at Wikimedia Commons
Data related toCommelinaceae at Wikispecies| National | |
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| Other | |
