Abies delavayi var. motuoensis

Pinaceae Abies delavayi var. motuoensis W.C.Cheng & L.K.Fu

Etymology
Abies refers to ‘to rise’; indicating large trees.
delavayi refers to the plant collector P. J. M. Delavay.
motuoensis refers to ‘Motuo’; the Mêdog County in Tibet.

Colloquial Name
Motuo fir

Description
These trees grow between 30 and 40 meters tall, with straight, column-like trunks that remain unbranched at the base. The crown is broad and pyramidal when young, becoming more flattened at the top as the tree ages. The bark of younger trees is smooth and varies from gray to brownish-gray. As the tree matures, the bark becomes deeply fissured and peels off in small fragments.

The main branches are thick and spread outward, with the upper ones angling slightly upward. The smaller secondary branches also spread outward and slightly upward. The twigs are stiff and rounded, with a color that ranges from dull maroon or brown to dark reddish-brown or purplish-brown, sometimes appearing glossy. As they age, they turn gray and may be smooth or have faint grooves. The young shoots are densely covered in rusty-colored hairs. The scars left by fallen leaves are somewhat angular or circular.

The buds are small, rounded, or sometimes up to 8 mm long on the leading shoots. They are very sticky with resin. The bud scales are broad, rounded at the tip, and reddish or greenish-brown, staying on the tree for several years before falling off. The needles are arranged in a spiral pattern and form several overlapping rows that spread outward. They vary in length and point slightly forward. On cone-bearing branches, they stand more upright. The needles measure between 2 and 3.2 cm long and are 1 to 2.8 mm wide. They are twisted at the base and have a long, narrow shape, often curving or forming an S-shape. The upper surface is glossy dark green, while the underside is bright white, sometimes with a waxy coating along the midrib. The edges are strongly curled under, making them appear even narrower. The tips can be either rounded or slightly notched. Stomata form two distinct bands on the underside.

The pollen cones grow along the lower sides of branches, hanging down from the bases of the needles. They measure 2 to 3.5 cm long, sometimes reaching 4 cm, and are yellow with violet-colored pollen-producing scales. The seed cones grow upright along the branches on short stalks that have many small scales. They are cylindrical or oblong in shape, measuring between 6 and 11 cm long. The tips are either flattened or slightly indented. When young, they are a deep violet-blue color, later darkening to purplish-black or nearly black, often with bluish bracts. As they ripen, they turn a dull reddish-brown. The cone’s central structure remains on the tree after the seeds are released, forming a thick, cone-shaped remnant that is purplish-brown.

The cone scales are fan-shaped and sometimes slightly triangular, measuring 1.2 to 2 cm in length and 1.5 to 2.5 cm in width at the middle of the cone. Their surface is smooth but has a fine fuzz. The upper part of the scale is thickened, with a rounded, slightly curled edge, while the sides have an irregular, somewhat jagged shape. The base of the scale narrows into a short stalk. The bracts inside the cone are oblong and spade-shaped, straight or slightly curved at the tip, with either small or long, narrow cusps. They measure 1 to 2 cm in length and are sometimes completely hidden inside the cone, but in some cases, they slightly extend past the cone scales, with their cusps spreading outward.

The seeds are oblong, 5 to 8 mm long, and brown, though they are often mostly covered by a dark, almost black wing membrane. The seed wings are wedge-shaped, measuring about 10 mm long and 6 mm wide, and range in color from light brown to a darker shade with a purplish-blue tint.

Subordinate Taxa
There exist 4 subordinate taxa for Abies delavayi:

Distribution

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TDWG Codes
3, 36, CHT

Habitat
The natural habitats for Abies delavayi var. motuoensis are temperate forests. It is naturally found at an elevation of at least 3800 up to 3800 metres. There are no conifers associated with Abies delavayi var. motuoensis that are known of.

USDA Hardiness zone – 7
Abies delavayi var. motuoensis is hardy to USDA Zone 7 (Bannister & Neuner, 2001), meaning its frost tolerance lies somewhere in the range of -17.8C (0F) to -12.2C (10F).

Species Continuity
The population trend for Abies delavayi var. motuoensis is unknown. There are no known threats for Abies delavayi var. motuoensis.

IUCN Category – LC
According to the IUCN Red List, Abies delavayi var. motuoensis has been assigned the status of LC(Least Concern). This means that according to the Red List criteria, this species is not qualified as threatened.

Superordinate Taxa
The nearest superordinate taxon for Abies delavayi is Subsect. Delavayianae. The coordinate taxa for Abies delavayi are therefore:

Abies delavayi var. motuoensis is further placed under Abietoideae. Abies delavayi var. motuoensis is also placed under Pinaceae.

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