| 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.
Geraniaceae is a family of flowering plants placed in the order Geraniales. The family name is derived from the genus Geranium. The family includes both the genus Geranium and the garden plants called geraniums, which modern botany classifies as genus Pelargonium, along with other related genera.
The Clusiaceae or GuttiferaeJuss. (1789) are a family of plants including 13 genera and ca 750 species. Several former members of Clusiacae are now placed in Calophyllaceae and Hypericaceae. They are mostly trees and shrubs, with milky sap and fruits or capsules for seeds. The family is primarily tropical. More so than many plant families, it shows large variation in plant morphology. According to the APG III, this family belongs to the order Malpighiales.
Iridaceae is a family of plants in order Asparagales, taking its name from the irises. It has a nearly global distribution, with 69 accepted genera with a total of c. 2500 species. It includes a number of economically important cultivated plants, such as species of Freesia, Gladiolus, and Crocus, as well as the crop saffron.
Pandanales, the pandans or screw-pines, is an order of flowering plants placed in the monocot clade in the Angiosperm Phylogeny Group and Angiosperm Phylogeny Web systems. Within the monocots Pandanales are grouped in the lilioid monocots where they are in a sister group relationship with the Dioscoreales. Historically the order has consisted of a number of different families in different systems but modern classification of the order is based primarily on molecular phylogenetics despite diverse morphology which previously placed many of the families in other groupings based on apparent similarity. Members of the order have a subtropical distribution and includes trees, shrubs, and vines as well as herbaceous plants. The order consists of 5 families, 36 genera and about 1,610 species.
Scilloideae is a subfamily of bulbous plants within the family Asparagaceae. Scilloideae is sometimes treated as a separate family Hyacinthaceae, named after the genus Hyacinthus. Scilloideae or Hyacinthaceae include many familiar garden plants such as Hyacinthus (hyacinths), Hyacinthoides (bluebells), Muscari and Scilla and Puschkinia. Some are important as cut flowers.
The Xyridaceae are a family of flowering plants. This family has been recognized by many taxonomists and is known as the yellow-eyed grass family.
Hydrocharitaceae is a flowering plant family including 16 known genera with a total of ca 135 known species, that including a number of species of aquatic plant, for instance the tape-grasses, the well known Canadian waterweed, and frogbit.
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. 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. The variation in morphology, especially that of the flower and inflorescence, is considered to be exceptionally high amongst the angiosperms.
Entomophily or insect pollination is a form of pollination whereby pollen of plants, especially but not only of flowering plants, is distributed by insects. Flowers pollinated by insects typically advertise themselves with bright colours, sometimes with conspicuous patterns leading to rewards of pollen and nectar; they may also have an attractive scent which in some cases mimics insect pheromones. Insect pollinators such as bees have adaptations for their role, such as lapping or sucking mouthparts to take in nectar, and in some species also pollen baskets on their hind legs. This required the coevolution of insects and flowering plants in the development of pollination behaviour by the insects and pollination mechanisms by the flowers, benefiting both groups. Both the size and the density of a population are known to affect pollination and subsequent reproductive performance.
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.
Triuridaceae are a family of tropical and subtropical flowering plants, including nine genera with a total of approximately 55 known species. All members lack chlorophyll and are mycoheterotrophic. The heterotrophic lifestyle of these plants has resulted in a loss of xylem vessels and stomata, and a reduction of leaves to scales.
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.
Cymodoceaceae is a family of flowering plants, sometimes known as the "manatee-grass family", which includes only marine species.
The Proteaceae form a family of flowering plants predominantly distributed in the Southern Hemisphere. The family comprises 83 genera with about 1,660 known species. Australia and South Africa have the greatest concentrations of diversity. Together with the Platanaceae, Nelumbonaceae and in the recent APG IV system the Sabiaceae, they make up the order Proteales. Well-known 'Proteaceae genera include Protea, Banksia, Embothrium, Grevillea, Hakea and Macadamia. Species such as the New South Wales waratah, king protea, and various species of Banksia, Grevillea, and Leucadendron are popular cut flowers. The nuts of Macadamia integrifolia are widely grown commercially and consumed, as are those of Gevuina avellana on a smaller scale.
Lacandonia is a mycoheterotrophic plant that contains no chlorophyll and has the unusual characteristic of inverted positions of the male (androecium) and female (gynoecium) floral parts, something that had not been seen in any other plants, with the exceptions of Trithuria and on occasion the related Triuris brevistylis.
Xerophyta is a plant genus in the family Velloziaceae named in 1789. 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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