Arctostaphylos myrtifolia

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Arctostaphylos myrtifolia
Arctostaphylosmyrtifolia.jpg

Arctostaphylos myrtifolia

Systematics
Class : Bedecktsamer (Magnoliopsida)
Asterids
Order : Heather-like (Ericales)
Family : Heather family (Ericaceae)
Genre : Bearberry ( Arctostaphylos )
Type : Arctostaphylos myrtifolia
Scientific name
Arctostaphylos myrtifolia
Parry

Arctostaphylos myrtifolia is a species of bearberry ( Arctostaphylos ) within the heather family(Ericaceae). This rare endemic only comes in the foothills of the Sierra Nevada in California before and is there english Ione manzanita called.

description

Habitus

Vegetative characteristics

Arctostaphylos myrtifolia grows as an evergreen, low to medium-high shrub with heights of 0.5 to 1.5 meters . The branches are prostrate or independently upright. The bark of the twigs is hairy with fine glands ( indument ). The durable, relatively thin, smooth bark is reddish with translucent grayish spots.

The alternate and upright leaves on the branches are divided into a petiole and a leaf blade. The petiole is 1 to 3 millimeters long. The simple, leathery leaf blade is 6 to 15 millimeters long and 3 to 8 millimeters wide and is narrow-elliptical with a wedge-shaped base. The even leaf margin is entire. The light green, glossy leaf surface is rough, papilose and sparsely covered with fine glandular hair.

Generative characteristics

The flowering time in the home area extends from winter to early spring. The nodding flowers stand together in terminal, single or single-branched, racemose inflorescences . The finely hairy inflorescence axis has a diameter of a little more than 1 millimeter and is 5 to 10 millimeters long. The tan to light brown, durable bracts are 1 to 2 millimeters in length, scale-shaped and triangular with a pointed upper end. The bracts are much shorter than the sepals. There are no cover sheets . The bare flower stalk is 1 to 3 millimeters long.

The hermaphroditic flowers are radial symmetry and five-fold with a double flower envelope . The five free sepals are durable. The five white petals are fused almost over their entire length to form an urn-shaped, early-falling corolla that ends in five short corolla lobes. An intrastaminal nectar disc is present. There are two circles, each with five free, fertile stamens that do not protrude above the corolla. The free stamens are widened. Each dark red dust bag has two thread-like appendages in the upper area and opens with a pore at the upper end. The upper ovary is hairy white. The straight stylus ends in a cephalic scar.

The bald drupes are almost cylindrical with a length of 3 to 4 millimeters. The exocarp is leathery or rarely thin and smooth. The endocarp contains several seeds. The stone cores of this species do not hang together at maturity.

The number of chromosomes is 2n = 26.

Occurrence and endangerment

Arctostaphylos myrtifolia is a rare endemic and only occurs in the foothills of the Sierra Nevada in California . It occurs only in Amador and Calaveras Counties . It occurs only near Ione in the eastern part of the Central Valley . It thrives at altitudes of 30 to 200 meters.

It grows in plant communities of the chaparral and in forest areas on pronounced acidic soils . There are only about 17 localities, but this species is common in some areas of its limited range. From The Nature Conservancy this type is classified as "Threatened" = "endangered" ( "G2"), 2015.

The main sources of endangerment for this rare endemic species are two fungal diseases. A cancer on the branches caused by some Fusicoccum species, including Fusicoccum aesculi , causes partial death, and tip and root rot caused by Phytophthora cinnamomi has destroyed entire populations of the species; This also prevents reintroduction on infected soils. These microorganisms as well as the newly identified Phytophthora cambivora are spreading rapidly and could soon have reached the entire range of the plant, which would lead to the extinction of the species. The United States Fish and Wildlife Service has recommended that it be upgraded from an endangered species to an endangered species.

Taxonomy

The first description of Arctostaphylos myrtifolia was in 1887 by Charles Christopher Parry in Pittonia , Volume 1, Issue 3, pages 34-35.

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literature

Individual evidence

  1. ↑ a b c d e f g h i j k l m n o p V. Thomas Parker, Michael C. Vasey, Jon E. Keeley: Arctostaphylos. : Arctostaphylos myrtifolia Parry , p. 414 - the same text online as the printed work , In: Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico. Volume 8: Paeoniaceae to Ericaceae , Oxford University Press, New York and Oxford, 2009, ISBN 978-0-19-534026-6 .
  2. ↑ a b c d e f g h V. Thomas Parker, Michael C. Vasey, Jon E. Keeley: Arctostaphylos myrtifolia Parry at Jepson eFlora .
  3. ↑ a b Arctostaphylos myrtifolia at Tropicos.org. Missouri Botanical Garden, St. Louis, Retrieved June 25, 2019.
  4. ↑ Comprehensive Report Species - Arctostaphylos myrtifolia . The Nature Conservancy. Retrieved June 24, 2019.
  5. ↑ TJ Swiecki, EA Bernhardt: Diseases threaten the survival of Ione manzanita ( Arctostaphylos myrtifolia ) . In: Phytosphere Research . March 10, 2003.
  6. ↑ Eriogonum apricum and Arctostaphylos myrtifolia . In: Five year Review . United States Fish and Wildlife Service, July 2010.
  7. ↑ Arctostaphylos myrtifolia in the Germplasm Resources Information Network (GRIN) USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved June 25, 2019.

Web links

Commons : Arctostaphylos myrtifolia  - collection of images, videos and audio files