Trochetia is a
genusIn biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of
flowering plantThe flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s from the
familyIn biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
MalvaceaeMalvaceae, or the mallow family, is a family of flowering plants containing over 200 genera with close to 2,300 species. Judd & al. Well known members of this family include okra, jute and cacao...
(formerly in the
SterculiaceaeSterculiaceae is a botanical name for a group of flowering plants at the rank of family, which is now considered obsolete. As is true for any botanical name, the circumscription, status and placement of the taxon has varied with taxonomic point of view...
, but this family is now usually subsumed in the Malvaceae). They are endemic to the
Mascarene IslandsThe Mascarene Islands is a group of islands in the Indian Ocean east of Madagascar comprising Mauritius, Réunion, Rodrigues, Cargados Carajos shoals, plus the former islands of the Saya de Malha, Nazareth and Soudan banks...
.
The genus was first described by
A.P. de CandolleAugustin Pyramus de Candolle also spelled Augustin Pyrame de Candolle was a Swiss botanist. René Louiche Desfontaines launched Candolle's botanical career by recommending him at an herbarium...
in 1823, who named it in honour of French botanist
Henri DutrochetRené Joachim Henri Dutrochet was a French physician, botanist and physiologist. He is best known for his investigation into osmosis.-Early Career:...
.
Description and ecology
The genus Trochetia consists of scrubs or small trees, which can reach a height from two to eight metres. The hermaphroditic flowers are either white (T. triflora), pink (T. parviflora), or reddish orange (T. boutoniana). They are either single-standing, or grow in a cluster of three flowers. Some species have bell-shaped petals. All plants of this genus are imperiled due to the competition of invasive species, like the
guavaGuavas are plants in the myrtle family genus Psidium , which contains about 100 species of tropical shrubs and small trees. They are native to Mexico, Central America, and northern South America...
s from China but also by destruction caused by introduced monkeys and rats. Five species occur on Mauritius and one on La Reunion. The habitat consists of humid forests with a high annual rainfall or mountainous slopes which are directed windwards.
Pollination
Plants from the genus Trochetia belong to the few plants worldwide that can produce coloured nectar. Some scientists, like the Danish ecologist Jens Olesen assume that this could be linked to bird species which have pollinated this plants in the past and are extinct today. However, recent research has demonstrated that not only do endemic Phelsuma geckos pollinate some of the species, but that they actually prefer coloured over clear nectar. Hence, the 'mystery of the Mauritian coloured nectar' can be considered at least partly solved now. Whether the nectar-feeding birds in Mauritius also react to the coloured nectar as a signal for floral reward remains to be seen.
The main pollinators of today are the
Mauritius Olive White-eyeThe Mauritius Olive White-eye is a very rare passerine from the family of white-eyes . It is endemic to the island of Mauritius.-Description:...
(Zosterops chloronothos) and the
Mauritius Grey White-eyeThe Mascarene White-eye , also known as Grey White-eye, is a small passerine from the family Zosteropidae, which is endemic to the islands of Mauritius and Réunion.-Taxonomy:...
(Zosterops borbonicus mauritianus), introduced
honey beeHoney bees are a subset of bees in the genus Apis, primarily distinguished by the production and storage of honey and the construction of perennial, colonial nests out of wax. Honey bees are the only extant members of the tribe Apini, all in the genus Apis...
s, or geckos from the genus
PhelsumaThe genus Phelsuma consists of several lizards in the gecko family, commonly referred to as Day Geckos.-Description:In contrast to most other gecko species, day geckos are active mainly during the day. Other diurnal geckos are members of the genus Lygodactylus and the genus Gonatodes...
.
Recent research has shown that in the absence of the locally extinct Mauritius Olive White-eye, Trochetia blackburnianas main pollinator in the area of Le Pétrin is the
Blue-tailed Day GeckoBlue-tailed day gecko is a diurnal species of geckos. It lives on the island Mauritius and typically inhabits warm and humid places and dwells on different trees and bushes.- Scientific synonyms :...
(Phelsuma cepediana). Interestingly, the pollination efficiency of these geckos depend on the proximity to dense patches of
PandanusPandanus is a genus of monocots with about 600 known species. They are numerous palmlike dioecious trees and shrubs native of the Old World tropics and subtropics. They are classified in the order Pandanales, family Pandanaceae.-Overview:...
, which are a favourite microhabitat for the geckos - possibly because the spiky leaves of Pandanus protect them from their main predator, the
Mauritius KestrelThe Mauritius Kestrel is a bird of prey from the family Falconidae endemic to the forests of Mauritius, where it is restricted to the southwestern plateau's forests, cliffs, and ravines.It is the most distinct of the Indian Ocean kestrels...
(Falco punctatus).
Species
Six species belong to that genus. Some authorities have classified much more species but these are either in doubt or synonyms of other plants. The similar Atlantic genus
TrochetiopsisThe flowering plant genus Trochetiopsis consists of two extant and one extinct species endemic to the island of Saint Helena...
was until 1981 included herein but actually Helmiopsis might be a closer relative of Trochetia (as is also suggested by
biogeographyBiogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...
). The formerly recognized species Trochetia richardii was reclassified as Helmiopsis richardii. Trochetia thouarsii was first synonymized with Trochetia pentaglossa and later reclassified as Nesogordonia thouarsii. Both plants are from Madagascar.
The following species are generally accepted:
- Trochetia parviflora
Trochetia parviflora is a very rare shrub from the Trochetia genus endemic to Mauritius. Traditionally included in the family Sterculiaceae, it is included in the expanded Malvaceae in the APG and most subsequent systematics.-Description:...
- an extremely rare tree (with about 63 individuals). Discovered in 1794. Thought to be extinct in 1863 and rediscovered on the slopes of Corps de GardeCorps de Garde is a 720 metre-high mountain of volcanic origin, in the area of the Moka Range between the Mountain Du Rempart and the Le Pouce Mountain in the Plaines Wilhems district of Mauritius. This basaltic rock has an imposing appearance which is characterized by an abruptly breakup and is...
, Mauritius in 2001 by a team from the Mauritius herbarium.
- Trochetia boutoniana
Trochetia boutoniana also known by its native Mauritian name Boucle d'Oreille is a shrub from the Trochetia genus endemic to Mauritius. Traditionally included in the family Sterculiaceae, it is included in the expanded Malvaceae in the APG and most subsequent systematics.-Description:It can reach a...
(native name: Boucle d'Oreille (in English: Earring tree) because of its bell-shaped look) is the national flower of Mauritius since 1992. It was named after French botanist Louis Bouton. The only occurrence are the slopes of Le Morne BrabantLe Morne Brabant is a peninsula at the extreme south-western tip of Mauritius and the most windward side of the island. It is highlighted by an eponymous single standing basaltic rock with a summit of 556 metres above sea level, the most imposing sight on Mauritius. The summit covers an area of...
, MauritiusMauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...
. The flowering time is from June to October.
- Trochetia uniflora - Occurrence: Trois Mamelles, Mont Le Pouce, and Letard Mountains in the west of Mauritius. Flowering time: May to June
- Trochetia triflora - Occurrence: Trou aux Cerfs
Trou aux Cerfs is a dormant volcano with a well-defined cone and crater. It is high and located in Curepipe, Mauritius. The crater has been alternately described as 300 and 350 meters in diameter, and is 80 meters deep. It is also known as Murr's Volcano. According to experts, the volcano is lying...
in the central, Grand BassinThe Grand Bassin is the largest body of open water along the Canal du Midi. It is in Castelnaudary France and covers some 7 hectares . Once a scene of intense economic activity, it is now a major pleasure port used by tourist craft...
, Piton Savanne, and Little Black River peak in the south-west of Mauritius. Flowering time: April to July
- Trochetia blackburniana - Occurrence: several places on Mauritius, most common species of that genus. Flowering time: April to May
- Trochetia granulata - Occurrence: Réunion
Réunion is a French island with a population of about 800,000 located in the Indian Ocean, east of Madagascar, about south west of Mauritius, the nearest island.Administratively, Réunion is one of the overseas departments of France...
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