Acanthophoenix
Encyclopedia
Acanthophoenix is a monoecious genus of flowering plant
in the palm
family from the Mascarene Islands
in the Indian Ocean
, where they are commonly called palmiste rouge. A genus long in flux, three species
are currently recognized, though unsustainable levels of harvesting for their edible palm hearts
have brought them all to near extinction in habitat. They are closely related to the Tectiphiala
and Deckenia genera, differing in the shape of the staminate flower
. The name combines the Greek
words for "thorn" and "date palm".
The solitary trunks are robust and conspicuously ringed, sparsely armed in youth, with a slightly swollen base. The tubular leaf
bases wrap the trunk, forming a 60 - 90 cm crownshaft
covered in hairy tomentum and spines. The leaves are pinnate, 2 m long, and borne on a tomentose petiole, sparsely to densely spiny. The leaflets emerge from the hairy rachis in a flat plane, dark green above and lighter below, to 30 cm long, once-folded with a red or yellow, toothed midrib.
The inflorescence
sprouts at the crownshaft base, branched to two orders with a short, winged, tomentose peduncle, colored brown and bearing spines. There is a single peduncular bract, the rachis long, often spiny, bearing ivory to red rachillae. The flowers are spirally arranged on first order rachillae, subtended by triangular bracts, with pairs or single staminate flowers on the tips; the branchlets elongate and become green in fruit.
The staminate flowers are asymmetrical, white to cream to red, the three sepals are short and imbricate, while the three valvate petal
s are three or four times as long. There are up to twelve stamens, exserted at antithesis, on elongated, slender to wide filaments. The anthers are dorsifixed, linear and basally sagittate; the pollen
is monosulcate and elliptic with tectate, reticulate exine. The pistillate flowers are ovoid with three broad, imbricate sepals and as many valvate petals. There may be up to nine tooth-like staminodes or none at all; gynoecium uniocular and ovoid with broad, pendulous stigmas. The fruit
is ellipsoidal to subglobose, maturing to black, with a thin endocarp, carrying one seed
. The seed is round with homogeneous endosperm and a basal embryo
.
They are restricted to Mauritius
and Réunion
though the populations have been so disturbed that conclusive statements about their ecology remain elusive. Because the islands were volcanically
formed, the palms are often found on sloping terrain from sea level to 1350 m. They are cultivated around the world but the native plants are gravely threatened.
Flowering plant
The 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...
in the palm
Arecaceae
Arecaceae or Palmae , are a family of flowering plants, the only family in the monocot order Arecales. There are roughly 202 currently known genera with around 2600 species, most of which are restricted to tropical, subtropical, and warm temperate climates...
family from the Mascarene Islands
Mascarene Islands
The 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...
in the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
, where they are commonly called palmiste rouge. A genus long in flux, three species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
are currently recognized, though unsustainable levels of harvesting for their edible palm hearts
Heart of palm
Heart of palm, also called palm heart, palmito, burglar's thigh, chonta, palm cabbage or swamp cabbage, is a vegetable harvested from the inner core and growing bud of certain palm trees Heart of palm, also called palm heart, palmito, burglar's thigh, chonta, palm cabbage or swamp cabbage, is a...
have brought them all to near extinction in habitat. They are closely related to the Tectiphiala
Tectiphiala
Tectiphiala ferox, or Palmiste Bouglé, is a species of flowering plant in the Arecaceae family.It is endemic to Mauritius.It is threatened by habitat loss.-Source:* Strahm, W. 1998. . Downloaded on 20 July 2007....
and Deckenia genera, differing in the shape of the staminate flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
. The name combines the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
words for "thorn" and "date palm".
Description
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
bases wrap the trunk, forming a 60 - 90 cm crownshaft
Crownshaft
An elongated circumferential leaf base formation present on some species of palm is called a crownshaft.The leaf bases of some pinnate leaved palms form a sheath at the top of the trunk surrounding the bud where all the subsequent leaves are formed.The crownshaft...
covered in hairy tomentum and spines. The leaves are pinnate, 2 m long, and borne on a tomentose petiole, sparsely to densely spiny. The leaflets emerge from the hairy rachis in a flat plane, dark green above and lighter below, to 30 cm long, once-folded with a red or yellow, toothed midrib.
The inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
sprouts at the crownshaft base, branched to two orders with a short, winged, tomentose peduncle, colored brown and bearing spines. There is a single peduncular bract, the rachis long, often spiny, bearing ivory to red rachillae. The flowers are spirally arranged on first order rachillae, subtended by triangular bracts, with pairs or single staminate flowers on the tips; the branchlets elongate and become green in fruit.
The staminate flowers are asymmetrical, white to cream to red, the three sepals are short and imbricate, while the three valvate petal
Petal
Petals are modified leaves that surround the reproductive parts of flowers. They often are brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals lying...
s are three or four times as long. There are up to twelve stamens, exserted at antithesis, on elongated, slender to wide filaments. The anthers are dorsifixed, linear and basally sagittate; the pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
is monosulcate and elliptic with tectate, reticulate exine. The pistillate flowers are ovoid with three broad, imbricate sepals and as many valvate petals. There may be up to nine tooth-like staminodes or none at all; gynoecium uniocular and ovoid with broad, pendulous stigmas. The fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
is ellipsoidal to subglobose, maturing to black, with a thin endocarp, carrying one seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
. The seed is round with homogeneous endosperm and a basal embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
.
Distribution and habitat
Mauritius
Mauritius , 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...
and Réunion
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...
though the populations have been so disturbed that conclusive statements about their ecology remain elusive. Because the islands were volcanically
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
formed, the palms are often found on sloping terrain from sea level to 1350 m. They are cultivated around the world but the native plants are gravely threatened.