Spruce asparagus

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Spruce asparagus
Spruce asparagus (Monotropa hypopitys)

Spruce asparagus ( Monotropa hypopitys )

Systematics
Asterids
Order : Heather-like (Ericales)
Family : Heather family (Ericaceae)
Subfamily : Monotropoideae
Genre : Monotropa
Type : Spruce asparagus
Scientific name
Monotropa hypopitys
L.

The spruce asparagus ( Monotropa hypopitys , Syn . : Hypopitys monotropa ) is a species of the heather family (Ericaceae). It has no chlorophyll and therefore cannot photosynthesize . As an epiparasite , it gets its nutrients from mycorrhizal fungi on trees and bushes nearby.

description

Illustration from CAM Lindman: Bilder ur Nordens Flora

The spruce asparagus is a leafy , perennial herbaceous plant that forms a rhizome to survive. This species differs from almost all other vascular plants native to Central Europe by the pale yellowish-brown color of the fleshy, waxy inflorescences . At most, there is a risk of confusion with the wild beard ( Epipogium aphyllum ) or the avian aviary ( Neottia nidus-avis ). Only the inflorescences appear above the ground.

The leaves are reduced to scales. At the end of the 10 to 30 centimeter long stem there are 2 to 15 (or 1 to 30, depending on the subspecies, see: Systematics) flowers in a nodding racemose inflorescence . The flowers are usually four-fold, but the terminal flower is mostly five-fold.

The elongated seeds are very small (0.1 mm long) and are produced in large numbers (many thousands per flower). The embryo is greatly reduced and consists of only four cells; the endosperm consists of only 9 cells.

distribution and habitat

The spruce asparagus is distributed over the temperate zones of the entire northern hemisphere (area formula : temperat (- boreal ) / circumpolar ). In North America the species goes south to Mexico and Guatemala , in Asia to the Himalayas , northern Thailand and Myanmar . In Europe it occurs mainly in the temperate area : to the north it reaches central Scandinavia , the Arctic Circle is only crossed very rarely. To the south it reaches the Mediterranean area with Italy and Greece , where it occurs mainly in the mountains.

The plants colonize a wide range of habitats , from willow bushes in coastal dunes to mountain coniferous forests. Typical habitat are moist, shady deciduous , coniferous and mixed forests , whereby due to the heterotrophic diet (see above) even the most light-poor biotopes can still be populated. The need for warmth of the spruce asparagus is also low, as the extreme vertical distribution from the planar to the subalpine altitude level and the occurrences beyond the Arctic Circle show. The locations of the species are almost always characterized by a high level of humidity. U. can also be replaced by a high total amount of precipitation.

Diet

In contrast to green, autotrophic plants, the spruce asparagus cannot build up ( assimilate ) the carbon compounds required for its nutrition from inorganic substances . Instead, it gets it from fungi that surround its roots with a dense network of hyphae ( mycorrhiza ): it is myco-heterotrophic. The mushrooms are knightly species (genus Tricholoma ), which in turn are ectomycorrhizal partners of trees. From these they receive organic carbon compounds, in return the fungi supply their tree partners with water and mineral nutrients. Trees are therefore the source of the carbon transferred to the spruce asparagus via the common hyphae network.

Björkmann was able to detect this indirect form of parasitism as early as 1960 through experiments with radioactively labeled tracers . He coined the term " epiparasitism " for it. In the English-speaking world, a “tripartite relationship” or “tripartite association” is also used. The spruce asparagus is therefore not a saprophyte , as has been wrongly stated over and over again until recently.

Germination and development

Since the tiny seeds contain almost no reserve substances, immediately after germination they are dependent on a compatible fungus surrounding the radicle, which protrudes only a little from the seed coat, and supplying it with nutrients. Then the root begins to grow and branch out. The growth takes place for a long time purely underground. At one of the sites investigated, a shrubbery of creeping willow in coastal dunes in Wales , the first buds appeared only after two years .

Flower and Propagation Biology

blossoms
Fruit cluster

The flowers are pollinated by insects (bumblebees), which are offered nectar as a reward. In addition, the flowers are probably also capable of self-pollination ( autogamy ), as shown not least by the very high, almost always complete fruit set.

The persistent, dry stem is elastic, the numerous seeds are extremely small and light. The spruce asparagus therefore belongs to the semachore plant species (wind and animal spreaders).

Phenology and population dynamics

Similar to the mushroom fruit bodies of their mycorrhizal partners, the inflorescences of the spruce asparagus appear late in the year, at the earliest from June. The flowering period extends from the end of June to the beginning of August, but can also drag on into September. New shoots are continuously formed while the older ones are already bearing fruit. Another parallel to mushrooms is the enormous speed with which new inflorescences are formed. After flowering, the now upright inflorescences lignify. As hibernators, they survive into the next vegetation period , when the dried up plants from the previous year can often be seen next to this year's plants.

Since only blooming shoots are formed, annual counts of the inflorescences are a good representation of the population size . It can fluctuate to a considerable extent (for example in a Finnish population by more than a hundredfold over an eleven-year observation period; Söyrinki 1985). The species seems to react sensitively to dry and warm weather conditions, the inflorescences then appear only in small numbers and may even fail to appear completely. In rainy years they develop well and can also occur in locations where they are otherwise not found.

Comparison with mycotrophic orchids

Pollen grain, colored

While the spruce asparagus is an exception among the heather family, there are around 100 species of orchids worldwide, such as the avian avian , which live mycotrophically in a similar way . In orchids, however, the fungi penetrate the roots and form haustoria there , which enable a much more intensive exchange of substances than with the superficial contact in the case of spruce asparagus. Therefore, mycotrophic orchids can do without the formation of a root system and produce their inflorescences right away.

Systematics

The first publication of Monotropa hypopitys was in 1753 by Carl von Linné .

Two subspecies have been described for Europe (which some authors also list as separate species):

  • Monotropa hypopitys subsp. hypopitys : style and anthers hairy, flowers pubescent on the inside, plant 10 to 15 flowers, capsule fruit longer than wide; under spruce trees. The number of chromosomes is 2n = 48. This subspecies is a character species of the order Piceetalia in Central Europe. In the Allgäu Alps, it rises in the Tyrolean part on the south-east ridge of the Rotwand up to an altitude of 1550 meters.
  • Monotropa hypopitys subsp. hypophegea (Wallr.) Holmb. ("Beech asparagus"): flowers bare inside, plants 3 to 6 (10) flowers, capsule fruit spherical; under beeches. The number of chromosomes is 2n = 16. This subspecies occurs in Central Europe in societies of the Luzulo-Fagenion sub-association.

However, both clans are connected by transitional forms, often grow next to each other and cannot be clearly separated chorologically and ecologically and sociologically.

Further subspecies are:

  • Monotropa hypopitys subsp. japonica : It occurs in Japan and East Asia.
  • Monotropa hypopitys subsp. lanuginosa (Michx.) H. Hara : It occurs in North America.

Hazardous situation and protection

Although the spruce asparagus occurs only scattered, it is still relatively widespread. However, like many mycotrophic plant species, it may be in decline. Ellenberg classified it as "dwindling" in 1991.

There was no endangerment according to the Red List of Endangered Plant Species in 1996 at the federal level. In the city-states of Hamburg and Berlin, the spruce asparagus is "critically endangered" (Red List Category 1). He is “highly endangered” (RL 2) in Saxony and Schleswig-Holstein. In North Rhine-Westphalia and Lower Saxony it is considered "endangered" (RL 3). In most of the other federal states (Bavaria, Brandenburg, Hesse, Mecklenburg-Western Pomerania, Rhineland-Palatinate, Saarland, Saxony-Anhalt and Thuringia) it is not classified as endangered. In Baden-Württemberg there is not enough data to classify it in a hazard category.

The main causes of danger are pollutant inputs from the air ( immissions ) as well as extensive over-fertilization ( eutrophication ), which can have a negative effect on mycorrhizal partners. The species should therefore benefit from supra-regional air pollution control measures.

In addition, no active nature conservation measures are necessary at the local level. However, larger clear cuts should be avoided because of the dependence of the spruce asparagus on the surrounding trees. On the other hand, careful management according to the principles of natural forestry probably does not endanger larger populations of spruce asparagus. Optimal conditions for the spruce asparagus are given in total reserves with the protection goal of process protection ( natural forest reserves , national parks ).

literature

  • Erik Björkmann: Monotropa hypopitys L. - an epiparasite on tree roots. In: Physiologia Plantarum , Volume 13, 1960, pp. 308-327.
  • Niilo Söyrinki: About the periodicity in blooming of Monotropa hypopitys (Monotropaceae) and some orchids in Finland. In: Annales Botanici Fennici , Volume 22, 1985, pp. 207-212.
  • JR Leake, SL McKendrick, MI Bitardondo, DJ Read: Symbiotic germination and development of the myco-heterotroph Monotropa hypopitys in nature and its requirement for locally distributed Tricholoma spp. In: New Phytologist , Volume 163, 2004, pp. 405-423. ( doi : 10.1111 / j.1469-8137.2004.01115.x )
  • SM Berch, HB Masicotte, LE Tackaberry: Re-publication of a translation of 'The vegetative organs of Monotropa hypopitys L.' published by F. Kamienski in 1882, with an update on Monotropa mycorrhizas. In: Mycorrhiza , Volume 15, 2005, pp. 323-332. ( doi : 10.1007 / s00572-004-0334-1 )

Web links

Commons : Spruce asparagus ( Monotropa hypopitys )  - album with pictures, videos and audio files

Individual evidence

  1. ↑ a b c J.R. Leake, SL McKendrick, M. Bidartondo, DJ Read: Symbiotic germination and development of the myco-heterotroph Monotropa hypopitys in nature and its requirement for locally distributed Tricholoma spp . In: New Phytologist 163 (2004), pp. 405-423.
  2. ↑ a b Monotropa in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved October 12, 2017.
  3. ↑ a b c d Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas . With the collaboration of Angelika Schwabe and Theo Müller. 8th, heavily revised and expanded edition. Eugen Ulmer, Stuttgart (Hohenheim) 2001, ISBN 3-8001-3131-5 , pp. 727-728 .
  4. ↑ Erhard Dörr, Wolfgang Lippert : Flora of the Allgäu and its surroundings. Volume 2, IHW, Eching 2004, ISBN 3-930167-61-1 , p. 298.