Armeria (Armeria helodes)

Description

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Armeria fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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Armeria description

Armeria helodes is a rare flowering plant found only in alkaline fens in a few isolated locations in Friuli, Italy ^{(1) (2) (3)}. A perennial species ^{(1) (2)}, it can be recognised by its small clusters of pale pink flowers, which are borne on a long, erect stem ^{(4) (5)}.

The leaves of Armeria helodes form a dense rosette around the base of the plant ^{(2) (4) (5) (6)}. Each light green leaf is long and narrow, measuring around 5 to 14 centimetres in length ^{(2) (4)}.

The flowering stems of Armeria helodes lack leaves ⁽⁴⁾ and end in a dense, globular cluster of flowers, or inflorescence ⁽⁵⁾, which measures around 1.2 to 2.2 centimetres across ⁽²⁾. Each flower has five petals, and the sepals of the flower, collectively known as the ‘calyx’, are fused to form a membranous, ribbed tube ^{(2) (5) (6)}. Below the inflorescence are membranous bracts which grow downwards to form a sheath around the upper part of the flowering stem ⁽⁵⁾.

As in other members of the Plumbaginaceae family, the fruit of Americahelodes is a dry, membranous, one-seeded achene ^{(5) (6)}, which is enclosed by the calyx ^{(2) (5) (6)}.

Armeria helodes is distinguished from the closely related Armeria purpurea mainly by its smooth leaf margins and from Armeria alpina by its larger leaves and longer flowering stem. It also differs from both species in having a short calyx and smaller bracts ⁽³⁾.

Synonyms

Armeria purpurea.

Size

Height: 25 - 45 cm ⁽²⁾

Armeria biology

The flowers of Armeria helodes are bisexual, containing both male and female reproductive organs ^{(5) (6)}, and appear between April and May ^{(1) (2)}.

Very little other information is available on the biology of this species, but it is known to prefer habitats that are low in nutrients and have high levels of direct sunlight, and it does not compete well with other plants ^{(1) (4)}. As in other members of the Plumbaginaceae family, the seeds of Armeria helodes are likely to be dispersed by the wind ⁽⁶⁾.

Armeria range

Armeria helodes is endemic to north-eastern Italy, where it is restricted to seven isolated locations in Friuli ^{(1) (2) (3)}.

This rare plant is now believed to occupy a total area of only 0.2 square kilometres ^{(1) (4) (7)}.

Armeria habitat

Armeria helodes occurs only in alkaline marshes, or fens, which are saturated with water and have peaty soils that are rich in calcium and magnesium ^{(1) (2) (3) (4)}. It occurs at elevations of up to 150 metres ⁽²⁾.

Armeria status

Armeria helodes is classified as Critically Endangered (CR) on the IUCN Red List ⁽¹⁾.

Armeria threats

At the start of the 20th century, Armeria helodes was widespread across around 60 square kilometres of wetlands. However, its habitat has been severely reduced and fragmented, and Armeria helodes is now restricted to seven isolated subpopulations in the few remaining habitat patches. Each subpopulation contains just five to ten mature plants, and Armeria helodes is considered to be at high risk of extinction ^{(1) (4) (7)}.

Although the remaining populations of this species are all in protected areas, its numbers are still decreasing. The main threat to Armeria helodes and its habitat is a falling water table, due to drainage, increased water extraction for agriculture and industry, and recurring drought as a result of decreasing rainfall in the region ^{(1) (4) (7)}. The few remaining habitat fragments are scattered between areas of agriculture and plantations ⁽⁴⁾, and are also threatened by a lack of habitat management, which has led to vegetation changes such as the encroachment of woody plants ⁽⁴⁾.

Pollution from fertilisers is also a threat to Armeria helodes. This species requires habitats that are calcium-rich but poor in other nutrients, and it cannot tolerate any increase in nutrients due to agricultural run-off ^{(1) (4)}. Due to its very specific habitat requirements, it is also unable to colonise other habitats, and it does not compete well with other plant species ⁽⁴⁾.

Armeria conservation

Armeria helodes is classified as ‘Critically Endangered’ in Italy ^{(1) (2)} and is listed as an important species in Annex II of the EU Habitats Directive, which aims to protect habitats and species across Europe ⁽⁸⁾.

All the sites where Armeria helodes occurs are protected as ‘Sites of Community Importance’ (SCIs), areas which contribute significantly to the conservation of a natural habitat or species, or to the protection of biodiversity ^{(1) (4) (7)}. However, the habitat of this species is still under threat and its overall numbers continue to decrease ⁽¹⁾.

Recommended conservation measures for Armeria helodes include further research and monitoring, and growing it ex-situ ^{(1) (2) (4)}. The alkaline fens where this species occur are an important habitat for a variety of species, and a number of conservation projects are underway to protect and restore them. These have included public awareness and education programmes, habitat restoration, appropriate habitat management, and the creation of a ‘buffer zone’ around important habitat areas ^{(4) (7)}.

During 2009, these projects found a slight increase in the Armeria helodes population, raising hopes that, with appropriate conservation measures, this highly endangered plant may be able to make a steady recovery ⁽⁴⁾.

Find out more

Find out more about the conservation of Armeria helodes and its habitat:

• Catalogazione Floristica per la Didattica - Armeria helodes:
  http://flora.uniud.it/scheda.php?id=1065 (In Italian)
• Life Friuli Fens:
  http://www.lifefriulifens.it/

More information on conservation in the Mediterranean Basin:

• Conservation International: Biodiversity Hotspots - Mediterranean Basin:
  http://www.biodiversityhotspots.org/xp/hotspots/mediterranean/Pages/biodiversity.aspx

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Glossary

Achene

A simple single-seeded fruit that falls from the plant in one piece. Achenes usually in occur in clusters.

Alkaline

Having a pH greater than 7.0. Soil is regarded as alkaline if it has a pH between 8.0 and 10.0. Alkaline soils are usually rich in calcium ions.

Bract

Modified leaf at the base of a flower.

Calyx

All of the sepals (floral leaves) of a flower, which form the protective outer layer of a flower bud.

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Ex-situ

Measures to conserve a species that occur outside of the natural range or habitat of the species. For example, in zoos or botanical gardens.

Fen

Wetland with alkaline, neutral or only slightly acidic peaty soil. The alkalinity arises due to ground water seeping through calcareous rocks (rocks containing calcium carbonate).

Inflorescence

The reproductive shoot of a plant, which bears a group or cluster of flowers.

Perennial

A plant that normally lives for more than two seasons. After an initial period, the plant produces flowers once a year.

Sepal

A floral leaf (collectively comprising the calyx of the flower) that forms the protective outer layer of a flower bud.

References

1. IUCN Red List (October, 2011)
   http://www.iucnredlist.org/
2. Catalogazione Floristica per la Didattica - Armeria helodes (October, 2011)
   http://flora.uniud.it/scheda.php?id=1065
3. Martini, F. and Poldini, L. (1987) Armeria helodes, a new species from north-eastern Italy. Candollea, 42(2): 533-544.
4. Life Friuli Fens (October, 2011)
   http://www.lifefriulifens.it/
5. Heywood, V.H. (1978) Flowering Plants of the World. Oxford University Press, Oxford.
6. Kubitzki, K., Rohwer, J.G. and Bittrich, V (Eds.) (1993) The Families and Genera of Vascular Plants. Volume II: Flowering Plants. Dicotyledons: Magnoliid, Hamamelid and Caryophyllid Families. Springer-Verlag, Berlin and Heidelberg.
7. Life Friuli Fens - Conservation and restoration of calcareous fens in Friuli (October, 2011)
   http://ec.europa.eu/environment/life/project/Projects/index.cfm?fuseaction=search.dspPage&n_proj_id=3165&docType=pdf
8. EU Habitats Directive (October, 2011)
   http://www.jncc.gov.uk/page-1374