''Mitrephora williamsii'' 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 The

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

Charles Budd Robinson Charles Budd Robinson, Jr. (October 26, 1871 – December 5, 1913) was a Canadian botanist and explorer. The standard author abbreviation C.B.Rob. is used to indicate this individual as the author when citing a botanical name. Early life Born in ...

, the Canadian botanist who first formally described the species, named it after

Robert Statham Williams Robert Statham Williams (May 6, 1859 – March 14, 1945) was an American bryologist who specialized in the mosses of the Yukon and South America. Early life Williams was born in Minneapolis, Minnesota on May 6, 1859. Since childhood, he had alw ...

who collected the specimen that Robinson examined.

Description

It is a tree reaching 12 meters in height. Its oval leaves are 20-32 by 7–11.5 centimeters and come to a point at their tips. The leaves are smooth and shiny green on their upper surfaces while their undersides are brown-green and slightly hairy. The leaves have 20-25 pairs of secondary veins emanating from their midribs. Its petioles are 12-18 by 2.5-4 millimeters. Its fragrant flowers are red and yellow and are arranged in

cymes 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 on ...

opposite the leaves. Each flower is on a 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 ...

5-8 millimeters long. Its flowers have 3, oval-shaped

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 ...

, 5-6 millimeters long, that come to a point at their tip. Its 6 petals are arranged in two rows of 3. The outer petals are 13-15 by 9-10 millimeters, hairy on their outer surface and smooth inside. The inner petals have a 10 by 2 millimeter claw below a 6-7 by 7.5 millimeter hood-shaped blade which is hairy on its inner surface. It has approximately 200-250

stamens 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 ...

that are 0.8-1 millimeter long.

Reproductive biology

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

Habitat and distribution

It has been observed growing in low elevation forests.

References

williamsii Flora of the Philippines Plants described in 1908 Taxa named by Charles Budd Robinson {{annonaceae-stub