''Pseuduvaria obliqua'' 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 The Annonaceae are a Family (biology), family of flowering plants consisting of trees, shrubs, or rarely lianas commonly known as the custard apple family or soursop family. With 108 accepted genera and about 2400 known species, it is the largest ...

. It is native to

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 Su and Richard Saunders, the botanists who first formally described the species, named it after its slightly uneven (, in Latin) leaf bases.

Description

It is a tree reaching 20 meters in height. The young, light to dark brown branches are very densely hairy and have sparse

lenticel 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 ...

s. Its elliptical to oval, papery leaves are 13-25 by 5-8 centimeters. The bases of the leaves are slightly uneven and pointed to broadly heart-shaped. The leaves have tapering tips, with the tapering portion 12-25 millimeters long. The leaves are hairless on their upper surfaces and sparsely hairy on their lower surfaces. The leaves have 14-18 pairs of secondary veins emanating from their midribs. Its very densely hairy petioles are 6-15 by 1.5-2.5 millimeters with a broad groove on their upper side. Its

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 occur in clusters of 2–4 on branches, and are organized on indistinct peduncles. Each inflorescence has a single flower. 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 ...

that is 9-16 by 0.4-0.8 millimeters. The pedicels are organized on a

rachis In biology, a rachis (from the grc, ῥάχις [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this c ...

up to 5 millimeters long that have up to 4

bract In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...

s. The pedicels have a medial, very densely hairy

that is 0.7-1 millimeters long. Its flowers are unisexual. Its flowers have 3 free, oval

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 ...

, that are 1-1.5 by 1-1.5 millimeters. The sepals are hairless on their upper surface, densely hairy on their lower surface, and hairy at their margins. Its 6 petals are arranged in two rows of 3. The cream-colored to light brown, oval, outer petals are 1.5-2.5 by 1.5-2 millimeters with hairless upper and densely hairy lower surfaces. The cream-colored to light brown, triangular inner petals have a 2.5-5.5 millimeter long

claw A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus ...

at their base and a 4.5-8 by 2.5-4 millimeter blade. The inner petals have slightly heart-shaped bases and pointed tips. The inner petals are very densely hairy on their upper and lower surfaces. The inner petals sometimes have a solitary, rod shaped, smooth, raised gland on their upper surface. The male flowers have 27-37

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 1-1.5 by 2-2.5 millimeters. The female flowers have 9-11

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'' ...

that are 1.4-1.7 by 0.6-1 millimeters. Each carpel has 1-2

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 arranged in a row. The fruit occur in clusters of 3-6 that are organized on indistinct peduncles. The fruit are attached by slightly hairy pedicles that are 19-21 by 1.5 millimeters. The green, mature globe-shaped fruit are 9-13 by 9-12 millimeters. The fruit are wrinkly, and densely hairy. Each fruit has up to 2 spherical, wrinkly seeds that are 6.5-8 by 6.5-7 by 3.5-4 millimeters.

Reproductive biology

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

Habitat and distribution

It has been observed growing in forests at elevations of 100–750 meters.

References

{{Taxonbar, from=Q17135352 obliqua Flora of Borneo Plants described in 2006 Taxa named by Yvonne Chuan Fang Su Taxa named by Richard M.K. Saunders