Amentotaxus
Encyclopedia
Amentotaxus is a genus of conifers
comprising five species, treated in either the Cephalotaxaceae
, or in the Taxaceae
when that family is considered in a broad sense. The genus is endemic
to subtropical southeastern Asia
, from Taiwan
west across southern China
to Assam
in the eastern Himalaya, and south to Vietnam
. The species are evergreen
shrub
s and small tree
s reaching 2-15 m tall.
The leaves
are spirally arranged on the shoots, but twisted at the base to lie in two flat ranks (except on erect leading shoots); they are linear-lanceolate, 4-12 cm long and 6-10 mm broad, soft in texture, with a blunt tip, green above, and with two conspicuous white stomatal bands below. They differ from the related genus Cephalotaxus
in the broader leaves, and from Torreya
by the blunt, not spine-tipped leaves.
The species can be either monoecious
or dioecious
; when monoecious, the male and female cones
are often on different branches. The male (pollen
) cones are catkin
-like, 3-15 cm long, grouped in clusters of 2-6 together produced from a single bud. The female (seed
) cones are single or grouped a few together on short stems; minute at first, they mature in about 18 months to a drupe
-like structure with the single large nut
-like seed 1.5-3 cm long surrounded by a fleshy covering, orange to red at full maturity; the apex of the seed usually protrudes slightly out of the fleshy covering.
Pinophyta
The conifers, division Pinophyta, also known as division Coniferophyta or Coniferae, are one of 13 or 14 division level taxa within the Kingdom Plantae. Pinophytes are gymnosperms. They are cone-bearing seed plants with vascular tissue; all extant conifers are woody plants, the great majority being...
comprising five species, treated in either the Cephalotaxaceae
Cephalotaxaceae
The family Cephalotaxaceae is a small grouping of conifers, with three genera and about 20 species, closely allied to the Taxaceae, and included in that family by some botanists. They are restricted to east Asia, except for two species of Torreya found in the southwest and southeast of the USA;...
, or in the Taxaceae
Taxaceae
The family Taxaceae, commonly called the yew family, includes three genera and about 7 to 12 species of coniferous plants, or in other interpretations , six genera and about 30 species....
when that family is considered in a broad sense. The genus is endemic
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...
to subtropical southeastern Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, from Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
west across southern China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
to Assam
Assam
Assam , also, rarely, Assam Valley and formerly the Assam Province , is a northeastern state of India and is one of the most culturally and geographically distinct regions of the country...
in the eastern Himalaya, and south to Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
. The species are evergreen
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...
shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
s and small tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s reaching 2-15 m tall.
The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are spirally arranged on the shoots, but twisted at the base to lie in two flat ranks (except on erect leading shoots); they are linear-lanceolate, 4-12 cm long and 6-10 mm broad, soft in texture, with a blunt tip, green above, and with two conspicuous white stomatal bands below. They differ from the related genus Cephalotaxus
Cephalotaxus
Cephalotaxus, commonly called Plum Yew or Cowtail Pine, is a genus of conifers comprising 11 species, treated in either the Cephalotaxaceae, or in the Taxaceae when that family is considered in a broad sense. The genus is endemic to eastern Asia, though fossil evidence shows it had a wider Northern...
in the broader leaves, and from Torreya
Torreya
Torreya is a genus of conifers comprising five or six species, treated in either the Cephalotaxaceae, or in the Taxaceae when that family is considered in a broad sense. Four are native to eastern Asia; the other two are native to North America. They are small to medium-sized evergreen trees...
by the blunt, not spine-tipped leaves.
The species can be either monoecious
Plant sexuality
Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....
or dioecious
Plant sexuality
Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....
; when monoecious, the male and female cones
Conifer cone
A cone is an organ on plants in the division Pinophyta that contains the reproductive structures. The familiar woody cone is the female cone, which produces seeds. The male cones, which produce pollen, are usually herbaceous and much less conspicuous even at full maturity...
are often on different branches. The male (pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
) cones are catkin
Catkin
A catkin or ament is a slim, cylindrical flower cluster, with inconspicuous or no petals, usually wind-pollinated but sometimes insect pollinated . They contain many, usually unisexual flowers, arranged closely along a central stem which is often drooping...
-like, 3-15 cm long, grouped in clusters of 2-6 together produced from a single bud. The female (seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
) cones are single or grouped a few together on short stems; minute at first, they mature in about 18 months to a drupe
Drupe
In botany, a drupe is a fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries...
-like structure with the single large nut
Nut (fruit)
A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...
-like seed 1.5-3 cm long surrounded by a fleshy covering, orange to red at full maturity; the apex of the seed usually protrudes slightly out of the fleshy covering.