''Pseuduvaria borneensis'' is a species of

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

in the family Annonaceae. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and eas ...

Yvonne Chuan Fang Su Yvonne Chuan Fang Su is a Hong Kong evolutionary biology, evolutionary biologist who is notable for her co-discovery of Pseuduvaria bruneiensis and Pseuduvaria borneensis. Her doctoral work at the University of Hong Kong focused on the Phylogenet ...

and

Richard M.K. Saunders Richard M. K. Saunders (born 1964) is a botanist. Work Among other subjects, his work has focused on the systematics and evolution of Annonaceae, a Family (biology), family of flowering plants. Legacy He is the authority for the followin ...

, the botanists who first formally described the species, named it after the regions of

where it is distributed including East Kalimantan,

Sabah Sabah () is a States and federal territories of Malaysia, state of Malaysia located in northern Borneo, in the region of East Malaysia. Sabah borders the Malaysian state of Sarawak to the southwest and the North Kalimantan province of Indone ...

and

Sarawak Sarawak (; ) is a States and federal territories of Malaysia, state of Malaysia. The largest among the 13 states, with an area almost equal to that of Peninsular Malaysia, Sarawak is located in northwest Borneo Island, and is bordered by the M ...

Description

It is a tree reaching 30 meters in height. Its branches have sparse

lenticels A lenticel is a porous tissue consisting of cells with large intercellular spaces in the periderm of the secondarily thickened organs and the bark of woody stems and roots of dicotyledonous flowering plants. It functions as a pore, providing a ...

. Its papery leaves are 13–20 by 3.5–8 centimeters and come to a point at their tips. The leaves are hairless on their upper surface and densely hairy on their lower surfaces. The leaves have 10–16 pairs of secondary veins emanating from their midribs. Its hairy petioles are 5–15 millimeters long with a groove on their upper side.

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. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

s are organized on short inconspicuous peduncles. Each inflorescence consists of 1–2 flowers. Each flower is on a densely hairy

pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures ...

4-9 millimeters in length. The flowers unisexual. Its flowers have 3

sepals A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined b ...

, 2–3 by 1.5–3 millimeters. The sepals are smooth on their upper surface, hairy on their lower surface, and have fine hairs on their margins. Its 6 petals are arranged in two rows of 3. The outer elliptical petals are 3–7.5 by 3.7.5 millimeters with smooth upper surfaces and densely hairy lower surfaces. The outer petals vary in color from light green to purple. The inner petals have a 4–9 millimeter long claw at their base and a 8–19 by 4–8 millimeter blade. The inner petals are smooth on their upper surface, densely hairy on their lower surface and have hairy margins. The inner surfaces of the inner petals have numerous distinctive glands. Male flowers have 100–143

stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filame ...

s that are 0.6–1.1 millimeters long. Female flowers have up to 15

carpels Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ''pistils'' ...

per flower and 6–7

ovule In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...

s per carpel. Fruit are on pedicels 5–21 millimeters in length. The fruit consists of up to 6 monocarps. Each mature monocarp is a 24–34 by 23–30 millimeter ellipsoid. The mature monocarps are green, wrinkly and have prominent ridges. Each monocarp has 6–9 seeds. The seeds are 15–19 by 6–9.5 millimeters.

Reproductive biology

The pollen of ''P. beccarii'' is shed as permanent tetrads.

Range and habitat

''Pseududuvaria borneensis'' is

to Borneo. It is widespread on the island, and is found in east and north Kalimantan in Indonesian Borneo, as well as in Sabah and Sarawak in Malaysian Borneo and in Brunei. The species' estimated

area of occupancy Area is the quantity that expresses the extent of a region on the plane or on a curved surface. The area of a plane region or ''plane area'' refers to the area of a shape or planar lamina, while '' surface area'' refers to the area of an open s ...

(AOO) is 52 km² and its estimated

extent of occurrence Extent may refer to: Computing * Extent (file systems), a contiguous region of computer storage medium reserved for a file * Extent File System, a discontinued file system implementation named after the contiguous region * Extent, a chunk of st ...

(EOO) is 176,441 km². It grows in primary and secondary lowland rain forests from 100 to 1,070 metres elevation. It often grows by streams on sandstone, clay, and coral limestone soils.

References

External links

* Endemic flora of Borneo Trees of Borneo Flora of Kalimantan Flora of Sabah Flora of Sarawak Flora of the Borneo lowland rain forests Plants described in 2006 borneensis Taxa named by Yvonne Chuan Fang Su Taxa named by Richard M.K. Saunders {{annonaceae-stub