| Velloziaceae Temporal range: Mid Neogene – Recent | |
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| Xerophyta retinervis | |
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Order: | Pandanales |
| Family: | Velloziaceae J.Agardh [1] |
| Genera | |
Velloziaceae is a family of monocotyledonous flowering plants. The APG II system, of 2003 (unchanged from the APG system, 1998), also recognizes this family, and assigns it to the order Pandanales.
By contrast to other members of Pandanales the family demonstrates stricter flower morphology. Despite that, the flower structure is still quite variable and with a lot of specifics. Thus morphological analyses are not able to uncover realistic phylogenetical relationships neither appropriate taxonomy. Embryological development places the family among the amaryllids while the composition of the ovary puts it near the distinct Hypoxidaceae. However, a study regarding the pollen structure in two genera from Velloziaceae was found to be an important character and suggests some correlation but this is still a variable trait.
Molecular analyses [2] recognize five distinct genera (by including Talbotia in Xerophyta and Nanuza in Vellozia thus forming two sister groups) and show that the monotypic genus Acanthochlamys is sister to the rest of the members. The family originated in Gondwana. The crown group is dated to be very young - 14 Mya (Mid Neogene) but the stem group was found to be much older - 108 Mya (Mid Cretaceous). [3] Velloziaceae has a total of 306 known species. [4]
| Velloziaceae |
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Members of Velloziaceae are distributed both in the Old and the New world. Genera as Vellozia , Nanuza and Barbacenia are found in South America (Brazil, Cerrado). Xerophyta and Talbotia are growing across Africa. Plants from the family are also found in Madagascar and the southern part of the Arabian Peninsula. One distinct species ( Acanthochlamys bracteata ) is restricted to China as the only member found in Asia.
Velloziaceae includes different xerophytes inhabiting open and dry habitats. [5] These plants exhibit various adaptations against desiccation as for example less-densely distributed stomata, decreased surface area by the use of developed furrows (as in many cacti) and expansive leaf sheets that cover the stem or the aerial roots until they grow long enough to reach the ground level. In some members these sheaths are able to create a microclimate that sustains the roots by keeping a constant level of moisture.
In the majority of Velloziaceae flowers are single or sometimes collected in bracts. There is no definite flowering period. They [6] are hypanthium-forming, sometimes papillate at their base or smooth, mostly white, creme or colored in different shades of purple although species with yellow, orange or red flowers also exist. Despite stricter, their structure is quite variable in some aspects (the number and structure of stamens varies at very high rate) as in other members of Pandanales. Tepals are six. The ovary is divided into three chambers with many ovules developed in them. Pistil and Stigma are also divided into three parts.
Examination with scanning electron microscope uncovers that one of the distinctive characteristics of the family is the structure [7] of the pollen. Its shape and composition are distinctive. For example, in Barbacenia pollen grains are singular and represent simple monads with ellipsoidal shape and one aperture. In Vellozia the grains are tetragonal (organized in tetrads) and non-apperturate. The size of pollen in Barbacenia is around half the size of that of Vellozia. However, the structure of the exine (pollen's envelopment) is a trait shared by the members of Velloziaceae. It is composed of many reticulations which in many cases may be described as vermiform. In some species, such as Vellozia abietina , the pollen wall does not fit this description, lacking any surface reticulations.
Both cross and self pollination are observed inside the family, and the process is accomplished in various manners. Pollinators of Vellozia include the common honeybee ( Apis mellifera ) and different species of solitary bees as Megachile curvipes , Psaenythia sp. and Augochlora metallica . The reward is pollen which is much more abundant than nectar. Nectar in the genus contains very low concentration of sugars. Bees use the three lobed stigma as a landing platform, and visually orient towards it. When the tepals are removed, bees will visit the flowers, but when the stigma is removed, no pollinators are recorded. It was found that hummingbirds visit these plants despite the diluted composition of nectar. Barbacenia differs in that its nectar is more abundant than its pollen. The pollen is probably taken by carpenter ants but whether ants are successful pollinators is not known. Pollen grains in Barbacenia are smaller, and these insects may be able to carry them and leave some on the stigma while they are searching for nectar.
Fruits and seeds [5] of these plants appear in large variety of shapes and sizes which demonstrate adaptations enhancing dispersal. Such adaptations include the development of bristles or hooks ( Talbotia elegans ) that cover the seed capsule. This allows attachment to animals, making the seeds able to travel long distances. Another characteristic is that the capsule is sticky, which also helps it to attach.
Ranunculaceae is a family of over 2,000 known species of flowering plants in 43 genera, distributed worldwide.
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Petrosaviaceae is a family of flowering plants belonging to a monotypic order, Petrosaviales. Petrosaviales are monocots, and are grouped within the lilioid monocots. Petrosaviales is a very small order composed of one family, two genera and four species accepted in 2016. Some species are photosynthetic (Japonolirion) and others are rare, leafless, chlorophyllous, mycoheterotrophic plants (Petrosavia). The family is found in low-light montane rainforests in Japan, China, Southeast Asia and Borneo. They are characterised by having bracteate racemes, pedicellate flowers, six persistent tepals, septal nectaries, three almost-distinct carpels, simultaneous microsporogenesis, monosulcate pollen, and follicular fruit.
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The Myristicaceae are a family of flowering plants native to Africa, Asia, Pacific islands, and the Americas and has been recognized by most taxonomists. It is sometimes called the "nutmeg family", after its most famous member, Myristica fragrans, the source of the spices nutmeg and mace. The best known genera are Myristica in Asia and Virola in the Neotropics.
Malpighiaceae is a family of flowering plants in the order Malpighiales. It comprises about 73 genera and 1315 species, all of which are native to the tropics and subtropics. About 80% of the genera and 90% of the species occur in the New World and the rest in the Old World.
Trochodendraceae is the only family of flowering plants in the order Trochodendrales. It comprises two extant genera, each with a single species along with up to five additional extinct genera and a number of extinct species. The living species are native to south east Asia. The two living species both have secondary xylem without vessel elements, which is quite rare in angiosperms. As the vessel-free wood suggests primitiveness, these two species have attracted much taxonomic attention.
Chloranthaceae is a family of flowering plants (angiosperms), the only family in the order Chloranthales. It is not closely related to any other family of flowering plants, and is among the early-diverging lineages in the angiosperms. They are woody or weakly woody plants occurring in Southeast Asia, the Pacific, Madagascar, Central and South America, and the West Indies. The family consists of four extant genera, totalling about 77 known species according to Christenhusz and Byng in 2016. Some species are used in traditional medicine. The type genus is Chloranthus. The fossil record of the family, mostly represented by pollen such as Clavatipollenites, extends back to the dawn of the history of flowering plants in the Early Cretaceous, and has been found on all continents.
The Stemonaceae are a family of monocotyledonous flowering plants placed in the order Pandanales. The family consists of four genera with ca 37 known species distributed in areas with seasonal climate across Southeast Asia and tropical Australia. One native species is found in the United States. In earlier systems the family was called Roxburghiaceae, after Roxburghia, now Stemona.
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Xerophyta is a genus of flowering plants in the family Velloziaceae. It was named in 1789 by de Jussieu. It is native to Africa, Madagascar, and the Arabian Peninsula.
The monocots are one of the two major groups of flowering plants, the other being the dicots. In order to reproduce they utilize various strategies such as employing forms of asexual reproduction, restricting which individuals they are sexually compatible with, or influencing how they are pollinated. Nearly all reproductive strategies that evolved in the dicots have independently evolved in monocots as well. Despite these similarities and their close relatedness, monocots and dicots have distinct traits in their reproductive biologies.
In botany, floral morphology is the study of the diversity of forms and structures presented by the flower, which, by definition, is a branch of limited growth that bears the modified leaves responsible for reproduction and protection of the gametes, called floral pieces.
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Data related to Velloziaceae at Wikispecies
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