''Mitrephora alba'' is a species of

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

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

Peninsular Malaysia Peninsular Malaysia, historically known as Malaya and also known as West Malaysia or the Malaysian Peninsula, is the western part of Malaysia that comprises the southern part of the Malay Peninsula on Mainland Southeast Asia and the list of isla ...

Henry Nicholas Ridley Henry Nicholas Ridley CMG (1911), MA (Oxon), FRS, FLS, F.R.H.S. (10 December 1855 – 24 October 1956) was an English botanist, geologist and naturalist who lived much of his life in Singapore. He was instrumental in promoting rubber trees i ...

, the English botanist who first

formally described A species description is a formal scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it differ ...

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 In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

are composed of up to 3 flowers on a

rachis In biology, a rachis (from the [], "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 case the ''rachi ...

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, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also lo ...

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 Etymology The term ''sepalum'' ...

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 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 Arthro ...

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 (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

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

carpels Gynoecium (; ; : gynoecia) 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) ...

that are 0.9-1.5 by 0.7-0.9 millimeters. Its

ovaries The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are endocr ...

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 sporangium, megasporangium), ...

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 In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branch ...

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 terpenes 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 a prima ...

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 toxic metals, toxic chemicals, microbe neurotoxins, radiation particles and even specific neurotransmitters when the system is out of balance. Also some types of dr ...

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 Scots united in the ninth century as the Kingdom of Alba, until it developed into the Kingd ...

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