Pogonotium
Encyclopedia
Pogonotium is a dioecious genus
of flowering plant
in the palm
family found in Malaysia and Borneo
. Its close relatives are climbing rattan
s and while partially armed with climbing apparatus, its habit is sprawling and leaning but not effective climbing. The reduced inflorescence nestled between the auricles is unusual and distinguishes it from similar relatives like Calamus, Daemonorops
and Ceratolobus
. The name is Greek
meaning "bearded".
has a tubular sheath with whorls and scatters of spines and hairy, brown tomentum, the sheath ending in a narrow, armed auricle on each side of the petiole. The petiole is abaxially rounded, adaxially flattened, hairy, and equipped with grapnel spines. The rachis is similarly armed, the leaflets widely spaced to crowded, linear, with one fold, and covered in bristles and scales; the midrib is adaxially prominent, the transverse veinlets are short yet conspicuous.
The inflorescence
, though axillary, is adnate to the internode and sheath of the following leaf, emerging erect between the auricles of the subtending leaf. In pistillate members it is branched to two orders, staminate to three; in both, a boat shaped, beak-ended prophyll encloses it. The prophyll may or may nor be armed and eventually develops a longitudinal split, exposing the flowers. The rachis bracts are small with free tips, the bracts on the first-order branches are tubular towards the base with triangular limbs.
The staminate flowers are solitary borne, on second and third order branches, subtended by a tiny, tubular, triangular bract and a two keeled bracteole. The tubular calyx is proximally striate, divided into three triangular lobes; the corolla is divided nearly to the base into three lobes. The six stamen are borne at the base of the corolla with fleshy, elongated filaments, inflexed at the tip, with oblong, medifixed anthers. The pollen is elliptic, diporate with rugulate to reticulate, tectate exine.
The larger pistillate flowers are borne in dyads, similarly subtended by a triangular bract, and accompanied by a sterile staminate flower and two, two keeled bracteoles. The sterile staminate flower is similar to the fertile but is slightly contorted with empty anthers. The pistillate has a striate, cup shaped calyx with triangular, valvate lobes, and the corolla splits to the base into similar triangular segments. There are six epipetalous staminodes, with triocular, triovulate, scaly, ovoid gynoecium and three fleshy, divergent, rugose stigmas, attached at the base. The fruit
is globose or ovoid, beaked, with apical stigmatic remains and covered in vertical rows or magenta to brown scales. The single seed
has a basal embryo
, a thick sarcotesta and a sweet, homogeneous endosperm.
forests called "kerangas". P. ursinum is confined to the Malaysian peninsula.
Genus
In 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 plant
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 found in Malaysia and Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....
. Its close relatives are climbing rattan
Rattan
Rattan is the name for the roughly 600 species of palms in the tribe Calameae, native to tropical regions of Africa, Asia and Australasia.- Structure :...
s and while partially armed with climbing apparatus, its habit is sprawling and leaning but not effective climbing. The reduced inflorescence nestled between the auricles is unusual and distinguishes it from similar relatives like Calamus, Daemonorops
Daemonorops
Daemonorops is a genus of rattan palms in the family Arecaceae found primarily in the tropics and subtropics of southeastern Asia.The stems of the Daemonorops are harvest for their cores, which is used for everything from canes to furniture. The fruits of certain species, in particular Daemonorops...
and Ceratolobus
Ceratolobus
Ceratolobus is a dioecious genus of flowering plant in the palm family found in Southeast Asia, commonly called rotan. They are only differentiated from close relatives like Korthalsia, Calamus, and Daemonorops by leaf sheath appendages or inflorescence variations...
. The name is 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;...
meaning "bearded".
Description
The trunks are both solitary and clustering with short internodes, usually covered in spiny, persistent leaf sheaths. The pinnate leafLeaf
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....
has a tubular sheath with whorls and scatters of spines and hairy, brown tomentum, the sheath ending in a narrow, armed auricle on each side of the petiole. The petiole is abaxially rounded, adaxially flattened, hairy, and equipped with grapnel spines. The rachis is similarly armed, the leaflets widely spaced to crowded, linear, with one fold, and covered in bristles and scales; the midrib is adaxially prominent, the transverse veinlets are short yet conspicuous.
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...
, though axillary, is adnate to the internode and sheath of the following leaf, emerging erect between the auricles of the subtending leaf. In pistillate members it is branched to two orders, staminate to three; in both, a boat shaped, beak-ended prophyll encloses it. The prophyll may or may nor be armed and eventually develops a longitudinal split, exposing the flowers. The rachis bracts are small with free tips, the bracts on the first-order branches are tubular towards the base with triangular limbs.
The staminate flowers are solitary borne, on second and third order branches, subtended by a tiny, tubular, triangular bract and a two keeled bracteole. The tubular calyx is proximally striate, divided into three triangular lobes; the corolla is divided nearly to the base into three lobes. The six stamen are borne at the base of the corolla with fleshy, elongated filaments, inflexed at the tip, with oblong, medifixed anthers. The pollen is elliptic, diporate with rugulate to reticulate, tectate exine.
The larger pistillate flowers are borne in dyads, similarly subtended by a triangular bract, and accompanied by a sterile staminate flower and two, two keeled bracteoles. The sterile staminate flower is similar to the fertile but is slightly contorted with empty anthers. The pistillate has a striate, cup shaped calyx with triangular, valvate lobes, and the corolla splits to the base into similar triangular segments. There are six epipetalous staminodes, with triocular, triovulate, scaly, ovoid gynoecium and three fleshy, divergent, rugose stigmas, attached at the base. 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 globose or ovoid, beaked, with apical stigmatic remains and covered in vertical rows or magenta to brown scales. The single 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...
has 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...
, a thick sarcotesta and a sweet, homogeneous endosperm.
Distribution and habitat
These are a tropical plant, P. divaricatum and P. moorei are sometimes found high on Bornean ridge tops from 700 to 1000 m in podsolized soils or in heathHeath forest
Heath forest is a type of tropical moist forest found in areas with acidic, sandy soils that are extremely nutrient-poor. Notable examples are the Rio Negro campinarana of the Amazon Basin in South America, and the Sundaland heath forests of Borneo and neighboring islands.-External links:**...
forests called "kerangas". P. ursinum is confined to the Malaysian peninsula.