Acmopyle
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Acmopyle pancheri with immature seed cones, the spherical epimatium and the elongated podocarpium are already clearly formed |
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Acmopyle is a genus of plants with only two species in the family of podocarpaceae (Podocarpaceae) within the conifers (Coniferales). About 55 million years old fossil finds of the genus show that it can be counted among the conifers that appeared comparatively early.
features
Acmopyle species form evergreen , small to medium-high trees with usually only a single trunk. The trunk bark is thin and fibrous, initially smooth and flakes off on older trees. Only a few branches are formed, which are arranged in dummy whorls. They form an initially conical and later more open crown. The branches are green, hairless and clearly grooved between the leaf bases, at least in the first year. One can distinguish long and short shoots, but they are similar. The buds are indistinct and consist of a collection of green scale leaves. Terminal buds are missing. The leaves are arranged in a spiral on the branches, forming two types of leaves: small, scale-shaped leaves on the long shoots, the dormant buds and at the base of short shoots and larger, needle-shaped leaves on the vegetative side branches. The leaves are single-nerved, laterally flattened, so have a left and a right side and are sickle-shaped to linear in shape. The leaves in the middle are significantly longer than at the base or end of the branches.
The wood is soft, light, not fragrant, yellowish brown to light brown. The core and sapwood are only indistinctly separated from each other. The grain is fine and even and shows clear growth rings. Resin channels are missing.
Acmopyle species are dioecious , possibly sometimes monoecious. The cat-like pollen cones grow individually or in small numbers, laterally or at the ends in the leaf axils of the branches, which are densely covered with scaly leaves. The pollen cones are cylindrical and have several small cover scales at their base. The microsporophylls grow spirally arranged along a thin axis on very short stalks. They are triangular and each have two pollen sacs, which contain the pollen, which is about 40 to 50 micrometers in size, with two air chambers.
The seed cones are usually single, rarely in pairs or in threes near the ends of twigs that are also densely overgrown with scale leaves. When ripe, they form an irregularly shaped, warty podocarpium from rarely four, but usually five to eight sterile cover scales, some of which remain visible. The seeds grow individually and stand almost upright from the cone when ripe. They are then almost completely surrounded by the fleshy epimatium , with bluish frosting when ripe , the base of which is partially covered by the podocarpium.
Seedlings form two two-veined cotyledons .
The basic chromosome number is x = 10.
Geographical distribution
One species is endemic to Viti Levu , the main island of the Republic of Fiji , and the other to New Caledonia .
ecology
The representatives of Acmopyle , like some other species from the stone slab family, form nodules with which the nitrogen from the air can be bound.
Systematics
Acmopyle is a genus in the stone slab family , in the order of the conifers (Coniferales). The genus was in 1903 by Robert Knud Friedrich Pilger set . The generic name Acmopyle comes from the Greek, akme denotes the highest point and pyle stands for "opening". It thus refers to the erect position of the ripe seeds.
Some characteristics are similar to those of other representatives of the stone slab family. For example, the seed cones with the well-developed podocarpium resemble those of the genera of stone slices ( Podocarpus ) and warts ( Dacrycarpus ). However, they consist of a larger number of cover scales, which also differ in terms of their warty surface and the remaining rudimentary seed scales. The leaves are laterally flattened, which only occurs in conifers in the genus Falcatifolium and in leaves on young representatives of the warthog. Similar leaves are known from fossil finds from the late Paleocene that are more than 55 million years old , which means that they can be counted among the conifer genera that appeared early on. The finds come from Antarctica, Argentina and the Australian states of Tasmania , New South Wales and Western Australia . Fossil finds after the Oligocene are not known. Older finds from the Jurassic , around 140 million years old , which resemble Acmopyle , are not assigned to the genus, nor are there any closer relationships. Due to the high age of the genus, there is also no close relationship to other stone shrubs, which is confirmed by genetic studies. The genera Podocarpus , Dacrydium and other close relatives of these genera are considered to be closest relatives , which is also supported by the similarity of the Podocarpium. However, Acmopyle has retained some more primitive features, such as the larger number of cover scales that make up the seed cone.
Two species are assigned to the genus:
- Acmopyle pancheri (Brongn. & Gris.) Pilg. : The needles are sickle-shaped or slightly S-shaped, in the middle of the branches 10 to 30 millimeters long, 1.5 to 3 millimeters wide and not ciliate. The pollen cones are 20 to 25 millimeters long and about 3 millimeters in diameter. The fully developed podocarpium is 15 to 20 millimeters long and has a diameter of 8 to 10 millimeters. The natural range is in New Caledonia.
- Acmopyle sahniana J. Buchholz & NE Gray : The needles are straight, sickle-shaped or slightly S-shaped, in the middle of the branches 10 to 25 millimeters long and from 0.6 usually 2 to 4 and rarely up to 4.8 millimeters wide and eyelashes. The pollen cones are 5 to 8 millimeters long and about 1.5 millimeters in diameter. The fully developed podocarpium is 7 to 9 millimeters long and 7 to 8 millimeters in diameter. The natural range is in Fiji.
use
Representatives of acmopyle are not cultivated, and no cultivars bred. However, you can find them in some botanical gardens.
swell
literature
- Aljos Farjon: A Handbook of the World's Conifers . tape 1 . Brill, Leiden-Boston 2010, ISBN 978-90-04-17718-5 , pp. 129 .
- James E. Eckenwalder: Conifers of the World. The Complete Reference . Timber Press, Portland, OR / London 2009, ISBN 978-0-88192-974-4 , pp. 119-121 .
Individual evidence
- ↑ a b c d e f g Aljos Farjon: A Handbook of the World's Conifers. Volume 1, p. 129.
- ↑ James E. Eckenwalder: Conifers of the World , pp. 119-120.
- ↑ a b c d e f g James E. Eckenwalder: Conifers of the World , p. 120.
- ↑ a b c d James E. Eckenwalder: Conifers of the World , p. 121.
- ^ Acmopyle in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved February 8, 2014.
- ^ Acmopyle. In: The International Plant Name Index. Retrieved February 9, 2014 .
- ^ Acmopyle. In: The Plant List. Retrieved February 8, 2014 .
