Cupressaceae Actinostrobus pyramidalis Miq.
Etymology
Actinostrobus refers to ‘star’ (actino) and ‘cone’ (strobus); indicating its six-scaled cone.
pyramidalis refers to its pyramidal habit.
Colloquial Name
Swan River cypress
Description
These shrubs or small trees grow densely and can reach heights between 2 and 6 meters. They have either a short trunk or multiple stems. The bark is smooth at first but begins to flake early, forming a thin, brownish-grey layer. The branches are numerous, growing upward or nearly straight, and remain on the plant for a long time. They form a crown that is usually narrow and either conical or pyramidal, though some plants have a more rounded shape. The smaller branches that bear foliage are also numerous, often twisted, and spread irregularly or grow upward. They are rigid, slender, short but sturdy, and have a slightly angular shape due to their leaf bases. As the leaves fall off, these branches turn grey-brown or grey.
The leaves grow in clusters of three, arranged in an alternating pattern along the branches. They extend downward along the stem and, in young plants, appear in their juvenile form. The leaves are narrow and lance-shaped, measuring between 2 and 5 millimeters long, sometimes reaching up to 8 millimeters, and about 1 to 1.5 millimeters wide. Their tips can either spread outward or curve inward slightly, and the underside has a raised central ridge. The edges and ridge have tiny teeth, and the leaf tapers to a sharp point. The color varies from green to a slightly purplish-green hue. Tiny openings for gas exchange, called stomata, are arranged in two lines on each surface of the leaf.
The pollen cones grow near the tips of the smallest branches. They are reddish-yellow when young and turn reddish-brown as they mature. They are small, measuring about 3 to 6 millimeters long and 1.5 to 2 millimeters wide. Each cone consists of 12 to 18 tiny overlapping scales, arranged in groups of three. These scales are round to oval with a pointed tip and have a slight ridge on the underside. Each one contains 2 to 4 small sacs that release pollen.
The seed cones grow at the ends of short, lateral branchlets, which are slightly thickened and have small leaves. They are usually clustered along the branches and stems. When closed, they have a rounded shape with a dome-like top, measuring between 12 and 15 millimeters in length and 12 to 16 millimeters in width. Young cones are green or purplish-green, but they mature to a purplish-brown or grey-brown color. The cone consists of six tightly packed, similarly sized scales arranged in a circular pattern. These are surrounded by 4 to 6 sets of broad, overlapping scale-like leaves, each set arranged in groups of three. The edges of these leaves have tiny teeth, and their tips are rounded with a small point. The tips of the bracts remain entirely hidden within the cone scales.
The cone scales are oblong, measuring 10 to 14 millimeters long and 5 to 6 millimeters wide. They are relatively flat and smooth, with a grey-brown outer surface and a purplish-brown or nearly black inner surface. Near the base, there are lighter-colored seed scars. At the center of the cone, there is a dark brown to blackish spike, about 5 to 7 millimeters long.
Each cone contains between 8 and 12 seeds, though only a few are fertile. About half of the seeds are positioned between the bases of the cone scales. They are irregularly shaped, either triangular or angular, and measure 3 to 5 millimeters in length. With their attached wings, they reach about 6 to 9 millimeters in total length. The seeds are yellowish-brown, while the wings are narrow, about 2 millimeters wide.
Distribution
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Habitat
The natural habitats for Actinostrobus pyramidalis are mediterranean-type shrublands. It is naturally found at an elevation of at least 300 up to 300 metres. There are no conifers associated with Actinostrobus pyramidalis that are known of.
USDA Hardiness zone – 10
Actinostrobus pyramidalis is hardy to USDA Zone 10 (Bannister & Neuner, 2001), meaning its frost tolerance lies somewhere in the range of -1.1C (30F) to 4.4C (40F).
Species Continuity
The population trend for Actinostrobus pyramidalis is unknown. There are ongoing threats for Actinostrobus pyramidalis and they are listed as follows:
IUCN Category – LC
According to the IUCN Red List, Actinostrobus pyramidalis 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 Actinostrobus pyramidalis is Actinostrobus. The coordinate taxa for Actinostrobus pyramidalis are therefore:
Actinostrobus pyramidalis is further placed under Cupressoideae. Actinostrobus pyramidalis is also placed under Cupressaceae.
This map shows botanical records (points) for this taxon. By opening the map’s sidebar (collapsed by default) you can toggle visibility or change the basemap. By clicking on records, you reveal more information.
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