Characteristics of Yunnan Catkin Yew (Amentotaxus yunnanensis) in the Wild
Published by Admin on 03/22/2022 In category Fruit Tree
Yunnan catkin yew (Amentotaxus yunnanensis) is a conifer in the genus Amentotaxus, native to Vietnam, China, and Laos.
This tree grows at elevations of 800-1600 m asl, with an annual rainfall of over 1500 millimeters and fog is common in this range. The circulation area is a hardiness zone 9 is associated with an average annual minimum temperature of -6.6 to 1.2 degrees Celsius.
Yunnan catkin yew mostly grows as a small tree in thickets and is scattered in deciduous forests. In Vietnam, it reached even greater heights of growth. Yunnan catkin yew is relatively shade tolerant and seedlings can grow successfully even under a closed canopy. The soil beneath is mostly karst.
Amentotaxus yunnanensis is often found together with other conifers such as Fokienia hodgins, Xanthocyparis vietnamensis, Pseudotsuga sinensis, Podocarpus neriifolius, Dacrydium elatum, Taxus chinensis, and deciduous trees.
In areas of silicate rocks such as granite and gneiss, this species often grows as a large tree among deciduous trees with only a few associated conifers such as Cephalotaxus mannii, Dacrycarpus imbricatus, and Nageia wallichiana.
The IUCN Redlist has categorized Amentotaxus yunnanensis as Vulnerable (VU).
The population of this tree may have decreased by 30 to 50 percent over the last 75 years due to forest conversion to agriculture and logging. Previously, Yunnan catkin yew was considered Endangered (EN), as stocks in China had decreased by more than 50 percent over the same period, and the distribution area in Vietnam, which is now considered a distribution focus, was unknown. Only a small part of the population grows in protected areas.
Characteristics of Yunnan Catkin Yew Leaf
The leaves grow in two rows and protrude from the branches at an angle of 50 to 70 degrees. They are almost sessile to short-stemmed, lanceolate or linear, usually straight or sometimes slightly crescent-shaped, 3.5-10 cm long and sometimes up to 15 cm long, while 1-2 cm wide.
The base is wide wedge-shaped to blunt and the needle narrows to a blunt or more or less pointed end. The tips of the leaves are slightly curled down. The leaves are light green to dark green, rough, and produce sclerenchyma cells that make the upper surface of the leaf mottled and wrinkled. The underside of the leaf shows two yellowish-white to pale brown stomata lines consisting of many scattered stomata separated from each other by the midrib and by two green bands from the margin of the needle.
The stomata stripes are 2-3 times wider than the green border stripes. The middle rib is significantly raised on the upper side of the needle and lies in a shallow groove 0.8 -1.0 mm wide-reaching its tip. On the underside of the leaf, the midrib is raised at least near the base of the needle and is 1-1.5 mm wide.
Characteristics of Yunnan Catkin Yew Fruit
Pollen cones are arranged in clusters of 12-20 pairs of cones 10-15 cm long. Usually, 4-6 groups grow together from large or almost terminal axillary buds.
The cones are round and about 3.5 mm long. Eight to ten shield-shaped microsporophylls, each containing 4-6 and sometimes up to eight pollen sacs.
The seed cones grow singly near the ends of the branches on thin stalks, curved downwards, 1.5-2 cm long with 8-10 decussates, keel covering scales, which cover the single stem, attaching the terminal ovule. The aril surrounding the seed is an elliptical or narrowly ovoid, 22-26 sometimes up to 30 mm long and 12-15 mm in diameter. It is smooth, bright red to reddish-purple when ripe, and has prickly tips. The seeds themselves are significantly smaller, about 18 mm long and 10 mm thick, oval to elliptical, and have small spiny tips.
The seeds are rich in oil which is extracted for medicinal use.
Characteristics of Yunnan Catkin Yew Tree
Yunnan catkin yew grows as an evergreen tree, it can reach a height of 30 meters, with a trunk diameter of up to 80 cm. The bark is brown, smooth, and peels off in a thin layer. The branches spread or ascend and form a broad crown. The needle branches grow opposite at a 45 to 80-degree angle on the branches. They are ascending or spreading, terete, and have alternating tortuous grooves, each connecting two-needle bases. They are green in the first year and turn light yellow to fawn in later years.
In China, wood is used to make furniture and tool handles. Possibility in Vietnam is used the same way. Yunnan catkin yew is sometimes used as bonsai.