''Mitrephora alba'' 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 native to

Peninsular Malaysia Peninsular Malaysia ( ms, Semenanjung Malaysia; Jawi: سمننجڠ مليسيا), or the States of Malaya ( ms, Negeri-negeri Tanah Melayu; Jawi: نڬري-نڬري تانه ملايو), also known as West Malaysia or the Malaysian Peninsula, ...

. Henry Nicholas Ridley, the English botanist who first formally described the species, named it after its white ( in Latin) flowers.

Description

It is a tree reaching 12 meters in height. Its branches have gray bark and are sparsely covered in fine pale brown hairs. Its leathery, oval to lance-shaped leaves are 6-18 by 3–6.5 centimeters with pointed to tapering tips and rounded or pointed to shallowly pointed bases. The upper surfaces of the leaves are matt and hairless and the undersides have sparse fine hairs. The leaves have 7-11 pairs of secondary veins emanating from their midribs. Its petioles are 2-6 by 1-2 millimeters and covered in sparse fine hairs. 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 ...

are composed of up to 3 flowers 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 ...

that is covered in pale brown velvety hair. Each flower is born on a fleshy

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 10-16 by 0.7-0.9 millimeters and densely covered in fine brown hairs. Oval

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 at the base of pedicels are 1-1.5 by 1 millimeters while those at top are 1-1.5 by 1-1.5 millimeters. Its oval to triangular

sepal 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 ...

s are 1.5-2.5 by 2.5-3 millimeters. The outer surfaces of the sepals have sparse, fine, brown hairs; the inner surfaces are hairless or nearly so. Its flowers have 6 petals in two rows of three. The white, oval, outer petals are 13-21 by 10-16 millimeters with pointed tips and wavy margins when mature. Both surfaces of the outer petals are sparsely covered in fine hairs. The inner petals are 9-15 by 5.5-11 millimeters and white with pink to purple highlights on their margins. The inner petals have a narrow claw below a somewhat tri-lobed blade, with the outer lobes rounded and the middle one pointed. The apices of the inner petals converge but are not fused. The outer surfaces of the inner petals are densely covered in fine hairs; the inner surface is covered in woolly hairs near tip. Its flowers have numerous oblong

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 ...

are 0.9-1.4 by 0.6-0.7 millimeters. Its flowers have up to 16

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 0.9-1.5 by 0.7-0.9 millimeters. Its

ovaries The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. T ...

have 5-10

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. Its fruit are found in clusters of 4–8. The oblong, sometimes kidney-shaped fruit are 1.6-3.8 by 1-1.8 centimeters. The fruit are warty to a variable degree, have a longitudinal ridge, and are sparsely covered in fine pale brown hairs. The fruit are born on 6-15 by 3–4.5 millimeter stipes that are sparsely covered in fine, gray-brown hairs. The stipes are attached to a

pedicels In botany, a pedicel is a stem that attaches a single flower to the inflorescence. Such inflorescences are described as ''pedicellate''. Description Pedicel refers to a structure connecting a single flower to its inflorescence. In the absenc ...

that is 9-17 by 1.5-4.5 millimeters and sparsely covered in fine hairs. The fruit have 5-10 seeds that are 10-12 by 7-9 millimeters.

Reproductive biology

The pollen of ''M. alba'' is shed as permanent tetrads.

Habitat and distribution

It has been observed growing in evergreen forests at elevations of 0 to 70 meters.

Uses

Bioactive

diterpenes Diterpenes are a class of chemical compounds composed of four isoprene units, often with the molecular formula C20H32. They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with geranylgeranyl pyrophosphate being ...

extracted from its branches have been reported to have moderate

cytotoxic Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating cells ...

activity in test with cultured human lung cancer cells.

References

{{Taxonbar, from=Q17139946

alba ''Alba'' ( , ) is the Scottish Gaelic name for Scotland. It is also, in English language historiography, used to refer to the polity of Picts and Scottish people, Scots united in the ninth century as the Kingdom of Alba, until it developed i ...

Flora of Peninsular Malaysia Plants described in 1915 Taxa named by Henry Nicholas Ridley