Haptanthus

Last updated

Haptanthus
Haptanthus-tree.jpg
Tree from re-discovery in 2010
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Buxales
Family: Buxaceae
Genus: Haptanthus
Goldberg & C.Nelson [1]
Species:
H. hazlettii
Binomial name
Haptanthus hazlettii
Goldberg & C.Nelson [2]

Haptanthus is a monotypic genus containing the sole species Haptanthus hazlettii, a shrub or small tree known only from the locality of Matarras in the Arizona Municipality in Honduras. Its flowers are unique among the flowering plants. A single "female" (carpellate) flower has two branches on either side which carry "male" (staminate) flowers. The flowers are very simple, lacking obvious sepals or petals. The family placement of the genus has been uncertain, but based on molecular phylogenetic research, it is included in the family Buxaceae as of September 2014. [3] Very few individuals have ever been found and its habitat is threatened by logging.

Contents

Description

Inflorescence showing central carpellate flower and lateral staminate flowers Haptanthus-pistil-stamens.jpg
Inflorescence showing central carpellate flower and lateral staminate flowers

Haptanthus hazlettii is a shrub [4] or tree. [3] It has opposite leaves spaced at 5.5–6.0 cm apart, usually arranged in two ranks (distichous). The leaves are simple with untoothed (entire) margins. There are no stipules. The leaf stalk (petiole) is short, 7–8 mm long, the leaf blade (lamina) 10–13.5 cm long by 4.1–5.6 cm wide. The entire plant is hairless (glabrous). [4]

The flowers are unisexual, carried on the same inflorescence (i.e. the plant is monoecious). One (or occasionally two) inflorescences emerge from a leaf axil, with at least five inflorescence-bearing axils per fertile branch. The inflorescences have a unique structure among flowering plants. In the centre there is a single carpellate ("female") flower. This lacks obvious petals or sepals (although there are small bracts below the flower which some researchers have suggested may be the remnants of the perianth [5] ), and consists solely of a single-celled (unilocular) ovary, 5 mm long by 2 mm wide, surmounted by three curved 4 mm long stigmas. On either side of the solitary carpellate flower there are two branches each with five or six staminate ("male") flowers arranged at 1–3 mm intervals. [4]

The structure of the staminate flowers has been interpreted differently. The original describers of the species, Aaron Goldberg and Cirilo Nelson, considered that each staminate flower was basically just a single stamen, with a flattened filament about 3–5 mm long grading into an anther about 2.5 mm long. [4] Two staminate flowers from the original specimen were re-examined by Andrew Doust and Peter Stevens. They concluded that each staminate flower definitely had two anthers, closely pressed together. They were unable to make a firm choice between two interpretations. The first is that the staminate flowers are basically as described by Goldberg and Nelson, except there are two stamens with fused or closely pressed filaments and anthers rather than one. The second, which they preferred, is that Goldberg and Nelson's "filament" is actually a pedicel (i.e. a stem on which the parts of the flower are carried) and that their "anther" consists of two closely pressed structures each made up of a tepal with a fused anther inside it. Either way, the flowers of Haptanthus hazlettii have "a morphology unlike that of any other angiosperm". [5]

Taxonomy

The sole species was first discovered in 1980 when a single specimen was collected by Donald L. Hazlett. [5] It was described scientifically in 1989 by Goldberg and Nelson, as a new genus and species, Haptanthus hazlettii. Initially Goldberg and Nelson were unable to assign Haptanthus to a family. [4] Nelson later placed it in its own family, Haptanthaceae. [6] In 2005, an attempt was made to obtain DNA for sequencing from the only known specimen, but this failed. Based on an analysis of the morphology of the specimen, Doust and Stevens suggested that Haptanthus was possibly related to the Buxales. [5] The APG III system of 2009 accepted the family Haptanthaceae, placing it in the order Buxales, along with the Buxaceae. [7] The close relationship with the Buxaceae was confirmed in 2011 when DNA was successfully obtained from a newly collected specimen. Molecular phylogenetic analysis showed that Haptanthus belongs inside the family Buxaceae rather than in a family of its own. [3] The APG IV system of 2016 includes Haptanthus in the family Buxaceae. [8]

Distribution, habitat and conservation

Haptanthus hazlettii has only been found in a very small area of tropical rain forest on the northern coast of Honduras, close to Matarras in the Arizona Municipality. [4] After the original specimen was collected in 1989, numerous attempts were made to find the species again but without success; the area had become covered with grass following tree clearance. It was thought that the species was perhaps extinct. [5] In 2010 an expedition organized by Alexey B. Shipunov and Ekaterina Shipunova found a single tree 2 km from the original collection point. A few more were later found nearby. Work to conserve the species is being led by the Lancetilla Botanical Garden of Tela, Honduras. [3]

Related Research Articles

<span class="mw-page-title-main">Alismatales</span> Order of herbaceous flowering plants of marshy and aquatic habitats

The Alismatales (alismatids) are an order of flowering plants including about 4,500 species. Plants assigned to this order are mostly tropical or aquatic. Some grow in fresh water, some in marine habitats. Perhaps the most important food crop in the order is the corm of the taro plant, Colocasia esculenta.

<span class="mw-page-title-main">Stamen</span> Male organ of a flower

The stamen is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium.

<span class="mw-page-title-main">Geraniaceae</span> Family of plants

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.

<span class="mw-page-title-main">Gunnerales</span> Order of flowering plants

The Gunnerales are an order of flowering plants. In the APG III system (2009) and APG IV system (2016) it contains two genera: Gunnera and Myrothamnus. In the Cronquist system (1981), the Gunneraceae were in the Haloragales and Myrothamnaceae in the Hamamelidales. DNA analysis was definitive, but the grouping of the two families was a surprise, given their very dissimilar morphologies. In Cronquist's old system, and Takhtajan's (1997), the Gunneraceae were in the Rosidae, and the Myrothamnaceae were in the Hamamelids. In modern classification systems such as APG III and APG IV this order was the first to derive from the core eudicots.

<span class="mw-page-title-main">Buxales</span> Order of eudicot flowering plants

The Buxales are a small order of eudicot flowering plants, recognized by the APG IV system of 2016. The order includes the family Buxaceae; the families Didymelaceae and Haptanthaceae may also be recognized or may be included in the Buxaceae. Many members of the order are evergreen shrubs or trees, although some are herbaceous perennials. They have separate "male" (staminate) and "female" (carpellate) flowers, mostly on the same plant. Some species are of economic importance either for the wood they produce or as ornamental plants.

<i>Amborella</i> Species of shrub

Amborella is a monotypic genus of understory shrubs or small trees endemic to the main island, Grande Terre, of New Caledonia in the southwest Pacific Ocean. The genus is the only member of the family Amborellaceae and the order Amborellales and contains a single species, Amborella trichopoda. Amborella is of great interest to plant systematists because molecular phylogenetic analyses consistently place it as the sister group to all other flowering plants.

<span class="mw-page-title-main">Piperaceae</span> Family of flowering plants in the order Piperales

The Piperaceae, also known as the pepper family, are a large family of flowering plants. The group contains roughly 3,600 currently accepted species in 5 genera. The vast majority of species can be found within the two main genera: Piper and Peperomia.

<span class="mw-page-title-main">Buxaceae</span> Family of flowering plants

The Buxaceae are a small family of six genera and about 123 known species of flowering plants. They are shrubs and small trees, with a cosmopolitan distribution. A seventh genus, sometimes accepted in the past (Notobuxus), has been shown by genetic studies to be included within Buxus.

<span class="mw-page-title-main">Elaeocarpaceae</span> Family of flowering plants

Elaeocarpaceae is a family of flowering plants. The family contains approximately 615 species of trees and shrubs in 12 genera. The largest genera are Elaeocarpus, with about 350 species, and Sloanea, with about 120.

<span class="mw-page-title-main">Sabiaceae</span> Family of flowering plants

Sabiaceae is a family of flowering plants that were placed in the order Proteales according to the APG IV system. It comprises three genera, Meliosma, Ophiocaryon and Sabia, with 66 known species, native to tropical to warm temperate regions of southern Asia and the Americas. The family has also been called Meliosmaceae Endl., 1841, nom. rej.

<span class="mw-page-title-main">Trochodendraceae</span> Family of flowering plants

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.

<span class="mw-page-title-main">Chloranthaceae</span> Family of flowering plants

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.

<i>Degeneria</i> Genus of flowering plants

Degeneria is a genus of flowering plants endemic to Fiji. It is the only genus in the family Degeneriaceae. The APG IV system of 2016, recognizes this family, and assigns it to the order Magnoliales in the clade magnoliids.

<i>Euptelea</i> Genus of flowering plants

Euptelea is a genus of two species of flowering plants in the monogeneric family Eupteleaceae. The genus is found from Assam east through China to Japan, and consists of shrubs or small trees:

<i>Didymeles</i> Genus of trees

Didymeles is a genus of flowering plants. It is variously treated as the only genus of the family Didymelaceae — or in the family Buxaceae, as in the APG IV system.

<i>Aphloia</i> Monotypic genus of flowering plants

Aphloia is a genus of flowering plants that contains a single species, Aphloia theiformis, the sole species of the monogeneric family Aphloiaceae. It is a species of evergreen shrubs or small trees occurring in East Africa, Madagascar, the Mascarene Islands and the Seychelles.

<i>Sphenostemon</i> Genus of small evergreen trees and shrubs

Sphenostemon is the genus of small evergreen trees or shrubs native to New Guinea, Queensland (Australia) and New Caledonia. They have opposite or spiral leaves, and at most small stipules. The small flowers, borne in terminal inflorescences, have free sepals and petals. The anthers have thick filaments. The fruit, a berry, is fleshy and contains two seeds. The genus is described as "particularly poorly known".

<span class="mw-page-title-main">Lepidobotryaceae</span> Family of flowering plants

Lepidobotryaceae is a family of plants in the order Celastrales. It contains only two species: Lepidobotrys staudtii and Ruptiliocarpon caracolito.

Nicobariodendron is a genus in the family Celastraceae, with only one species, Nicobariodendron sleumeri, a tree with simple, alternately set, entire leaves, small flowers and single seed fleshy fruits. It is only known from the Nicobar Islands of India.

References

  1. ↑ "IPNI Plant Name Query Results for Haptanthus", The International Plant Names Index , vol. 14, retrieved 2014-09-27
  2. ↑ "Haptanthus hazlettii", The Plant List, retrieved 2014-09-27
  3. 1 2 3 4 Shipunov, A. & Shipunova, E. (2011), "Haptanthus story: Rediscovery of enigmatic flowering plant from Honduras", American Journal of Botany, 98 (4): 761–763, doi:10.3732/ajb.1000307, PMID   21613172
  4. 1 2 3 4 5 6 Goldberg, Aaron & Nelson S., Cirilo (1989), "Haptanthus, a New Dicotyledonous Genus from Honduras", Systematic Botany, 14 (1): 16–19, doi:10.2307/2419047, JSTOR   2419047
  5. 1 2 3 4 5 Doust, A.N. & Stevens, P.F. (2005), "A Reinterpretation of the Staminate Flowers of Haptanthus" (PDF), Systematic Botany, 30 (4): 779–785, doi:10.1600/036364405775097833, JSTOR   25064109, S2CID   13725762 [ permanent dead link ]
  6. ↑ Nelson S., C. (2001), "Plantas descritas originalmente de Honduras y sus nomenclaturas equivalentes actuales" (PDF), Ceiba (in Spanish), 42 (1): 1–71, retrieved 2014-09-27[ permanent dead link ], p. 33
  7. ↑ Angiosperm Phylogeny Group (2009), "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III", Botanical Journal of the Linnean Society, 161 (2): 105–121, doi: 10.1111/j.1095-8339.2009.00996.x
  8. ↑ Angiosperm Phylogeny Group (2016). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV". Botanical Journal of the Linnean Society . 181 (1): 1–20. doi: 10.1111/boj.12385 . ISSN   0024-4074.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.