Henning Eiler (Ejler) Petersen (22 August 1877 – 22 May 1946) was a

Danish Danish may refer to: * Something of, from, or related to the country of Denmark People * A national or citizen of Denmark, also called a "Dane," see Demographics of Denmark * Culture of Denmark * Danish people or Danes, people with a Danish a ...

mycologist Mycology is the branch of biology concerned with the study of fungus, fungi, including their genetics, genetic and biochemistry, biochemical properties, their Taxonomy (biology), taxonomy and ethnomycology, their use to humans, including as a so ...

botanist Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...

and

marine biologist Marine biology is the scientific study of the biology of marine life, organisms in the sea. Given that in biology many scientific classification, phyla, family (biology), families and genera have some species that live in the sea and others th ...

. He made a major contribution to unveiling the mysterious die-back of

eel grass Eelgrass is a common name for several plants and may refer to: * ''Zostera'', marine eelgrass * ''Vallisneria ''Vallisneria'' (named in honor of Antonio Vallisneri) is a genus of freshwater aquatic plant, commonly called eelgrass, tape grass or ...

in Northern

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

an waters in the early 20th century as a

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

outbreak In epidemiology, an outbreak is a sudden increase in occurrences of a disease when cases are in excess of normal expectancy for the location or season. It may affect a small and localized group or impact upon thousands of people across an entire ...

. Petersen's main research was in what was then known as ''lower fungi'' –

Chytridiomycota Chytridiomycota are a division of zoosporic organisms in the kingdom Fungi, informally known as chytrids. The name is derived from the Ancient Greek ('), meaning "little pot", describing the structure containing unreleased zoöspores. Chytrids ...

and

Oomycetes Oomycota forms a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the result ...

, but he also studied the

systematics Biological systematics is the study of the diversification of living forms, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees (synonyms: cladograms, phylogenetic tre ...

Red algae Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority ...

. Parallel to these lines of research, he investigated the intraspecific morphological variation in plant species – which would today be called

quantitative genetics Quantitative genetics deals with phenotypes that vary continuously (such as height or mass)—as opposed to discretely identifiable phenotypes and gene-products (such as eye-colour, or the presence of a particular biochemical). Both branches u ...

. The Oomycete genus '' Petersenia'' is named to his honour.

Selected scientific bibliography

* Petersen, H.E. (1903) Notes sur les Phycomycètes observés dans les téguments vides des nymphes de Phryganées avec description de trios espèces nouvelles de Chytridinées. Journal de Botanique 17 (6–7): 214–222. * Petersen, H.E. (1905) Contributions à la connaissance des Phycomycètes marins (''Chrytridinæ'' Fischer). Oversigt over det

Kongelige Danske Videnskabernes Selskab {{Infobox organization , name = The Royal Danish Academy of Sciences and Letters , full_name = , native_name = Det Kongelige Danske Videnskabernes Selskab , native_name_lang = , logo = Royal ...

s Forhandlinger 1905 (5): 439–488 * Petersen, H.E. (1908) Danske Arter af Slægten '' Ceramium'' (Roth)

Lyngbye Hans Christian Lyngbye (29 June 1782 – 18 May 1837) was a Danish priest and Botany, botanist, specialising in algae. Life Hans Christian Lyngbye was born in Aalborg, Denmark, in 1782, the son of a teacher, Jens Michelsen Lyngbye. He attended the ...

ith French summary

s Skrifter - Naturvidenskabelig og Mathematisk Afdeling, 7.Rk., vol. 5 (2). * Petersen, H.E. (1908) The structure and biology of Arctic flowering plants (ed. E. Warming. 1. Ericinæ (

Ericaceae The Ericaceae are a family of flowering plants, commonly known as the heath or heather family, found most commonly in acidic and infertile growing conditions. The family is large, with c.4250 known species spread across 124 genera, making it th ...

, Pirolaceae). 2. The biological anatomy of them leaves and stems.

Meddelelser om Grønland ''Meddelelser om Grønland'' ("''Communications on Greenland''") is a Danish scientific periodical which publishes scientific results from all fields of research on Greenland. It was established by Frederik Johnstrup and published as a single seri ...

36: 73–138. * Petersen, H.E. (1908) The structure and biology of Arctic flowering plants (ed. E. Warming. 2.

Diapensiaceae Diapensiaceae is a small family of flowering plants, which includes 15 species in 6 genera. The genera include '' Berneuxia'' Decne. (1 species), '' Diapensia'' L. (5 species), ''Galax'' Sims (1 species), '' Pyxidanthera'' Michx. (2 species), '' ...

. ''

Diapensia lapponica ''Diapensia lapponica'', the pincushion plant, is a plant in the family Diapensiaceae, the only circumboreal species in the genus '' Diapensia'', the others being mainly in the Himalaya and on mountains in southwestern China. This species likely ...

''.

36: 139–154. * Petersen, H.E. (1910) An account of Danish freshwater Phycomycetes, with biological and systematical remarks. Annales Mycologici 8: 494–560. * Ostenfeld, C.H. & Petersen, H.E. (1930) On a new Plasmodiophoracea found in Canada. Zeitschrift für Botanik 23: 13–18. * Petersen, H. E. (1915) Indledende Studier over Polymorfien hos '' Anthriscus silvestris'' (L.) Hoffm. Dansk Botanisk Arkiv 1: 1–150. * Petersen, H.E. (1924) Studier over Polymorphien hos ''

Vaccinium uliginosum ''Vaccinium uliginosum'' (bog bilberry, bog blueberry, northern bilberry or western blueberry) is a Eurasian and North American flowering plant in the genus ''Vaccinium'' within the heath family. Distribution ''Vaccinium uliginosum'' is native ...

''. Botanisk Tidsskrift 38 (3). * Petersen, H.E. (1921) Nogle Studier over ''

Pimpinella saxifraga ''Pimpinella saxifraga'', known as burnet-saxifrage, solidstem burnet saxifrage, lesser burnet is a plant species in the family Apiaceae, a native of the British Isles and temperate Europe and Western Asia. It is neither a burnet, which its l ...

'' L.

Botanisk Tidsskrift ''Botanisk Tidsskrift'' (standard abbreviation ''Bot. Tidsskr.'') was a Danish mixed scientific and amateur journal concerning botany, issued in Copenhagen by the Danish Botanical Society. It was published from 1866 to 1980, when it fused with Bot ...

37: 222–240. * Petersen, H.E. (1922) Études ultérieures sur la polymorphie de l Anthriscus silvester'' (L.) Hoffm. Dansk Botanisk Arkiv 4: 1–28. * Petersen, H.E. (1926) Über die Variation der ''

Potentilla erecta ''Potentilla erecta'' (syn. ''Tormentilla erecta'', ''Potentilla laeta'', ''Potentilla tormentilla'', known as the (common) tormentil, septfoil or erect cinquefoil ) is a herbaceous perennial plant belonging to the rose family (Rosaceae). Descri ...

'' (L.) Dalla Torre.

39: 368–374. * Petersen, H.E. (1933) Wasting disease in eel grass (

Zostera marina ''Zostera marina'' is a flowering vascular plant species as one of many kinds of seagrass, with this species known primarily by the English name of eelgrass with seawrack much less used, and refers to the plant after breaking loose from the submer ...

Nature Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...

134: 143–144. * Petersen, H.E. (1935) Preliminary report on the disease of eel-grass (

L.). Report from the Danish Biological Station 40: 3–8.

References

1877 births 1946 deaths 20th-century Danish botanists Danish mycologists Danish marine biologists {{Mycologist-stub