Editing Eucalyptus (section)

==History==
Although eucalypts must have been seen by the very early European explorers and collectors, no botanical collections of them are known to have been made until 1770 when [[Joseph Banks]] and [[Daniel Solander]] arrived at [[Botany Bay]] with [[Captain James Cook]]. There they collected specimens of ''E. gummifera'' and later, near the [[Endeavour River]] in northern ''Queensland'', ''E. platyphylla''; neither of these species was named as such at the time.{{cn|date=June 2024}}

In 1777, on Cook's third expedition, David Nelson collected a eucalypt on [[Bruny Island]] in southern [[Tasmania]]. This specimen was taken to the [[British Museum]] in [[London]], and was named ''Eucalyptus obliqua'' by the French botanist [[Charles Louis L'Héritier de Brutelle|L'Héritier]], who was working in London at the time.<ref>{{ cite book |last=L'Héritier |first=Charles Louis |author-link=Charles Louis L'Héritier de Brutelle |year=1788 |title=Sertum Anglicum, seu, Plantae rariores quae in hortis juxta Londinum : imprimis in horto regio Kewensi excoluntur, ab anno 1786 ad annum 1787 observatae |place=Paris |publisher=Petri Francisci Didot |page=11 |language=la |url=https://www.biodiversitylibrary.org/page/11832429 }}</ref> He coined the generic name from the Greek roots ''eu'' and ''calyptos'', meaning "well" and "covered" in reference to the [[operculum (botany)|operculum]] of the flower bud which protects the developing flower parts as the flower develops and is shed by the pressure of the emerging [[stamens]] at flowering.<ref name=":2" />

The name ''obliqua'' was derived from the Latin ''obliquus'', meaning "oblique", which is the [[botany|botanical]] term describing a [[leaf]] base where the two sides of the leaf blade are of unequal length and do not meet the petiole at the same place.{{cn|date=June 2024}}

''E. obliqua'' was published in 1788–89, which coincided with the European colonisation of Australia. Between then and the turn of the 19th century, several more species of ''Eucalyptus'' were named and published. Most of these were by the English botanist [[James Edward Smith (botanist)|James Edward Smith]] and most were, as might be expected, trees of the [[Sydney]] region. These include the economically valuable ''E. pilularis'', ''E. saligna'' and ''E. tereticornis''.{{cn|date=June 2024}}

The first endemic Western Australian ''Eucalyptus'' to be collected and subsequently named was the Yate (''[[Eucalyptus cornuta|E. cornuta]]'') by the French botanist [[Jacques Labillardière]], who collected in what is now the [[Esperance, Western Australia|Esperance]] area in 1792.<ref name=FieldGuide/>

Several Australian botanists were active during the 19th century, particularly [[Ferdinand von Mueller]], whose work on ''eucalypts'' contributed greatly to the first comprehensive account of the genus in [[George Bentham]]'s ''Flora Australiensis'' in 1867. The account is the most important early systematic treatment of the genus. Bentham divided it into five series whose distinctions were based on characteristics of the stamens, particularly the anthers (Mueller, 1879–84), work elaborated by [[Joseph Henry Maiden]] (1903–33) and still further by [[William Blakely|William Faris Blakely]] (1934). The anther system became too complex to be workable and more recent systematic work has concentrated on the characteristics of buds, fruits, leaves and bark.

===Species and hybrids===
{{Main|List of Eucalyptus species}}
Over 700 [[species]] of ''Eucalyptus'' are known. Some have [[divergent evolution|diverged]] from the mainstream of the [[genus]] to the extent that they are quite isolated [[genetics|genetically]] and are able to be recognised by only a few relatively invariant characteristics. Most, however, may be regarded as belonging to large or small groups of related species, which are often in geographical contact with each other and between which [[gene]] exchange still occurs. In these situations, many species appear to grade into one another, and intermediate forms are common. In other words, some species are relatively fixed genetically, as expressed in their [[morphology (biology)|morphology]], while others have not diverged completely from their nearest relatives.{{cn|date=June 2024}}

Hybrid individuals have not always been recognised as such on first collection and some have been named as new species, such as ''E. chrysantha'' (''E. preissiana'' × ''E. sepulcralis'') and ''E.'' "rivalis" (''E. marginata'' × ''E. megacarpa''). Hybrid combinations are not particularly common in the field, but some other published species frequently seen in Australia have been suggested to be hybrid combinations. For example, ''[[Eucalyptus × erythrandra]]'' is believed to be ''E. angulosa'' × ''E. teraptera'' and due to its wide distribution is often referred to in texts.<ref name=FieldGuide/>

[[Renantherin]], a phenolic compound present in the leaves of some ''Eucalyptus'' species, allows [[chemotaxonomy|chemotaxonomic]] discrimination in the sections [[renantheroideae]] and [[renantherae]]<ref>{{cite journal |doi=10.1016/S0031-9422(00)82772-7 |volume=6 |title=Polyphenols in the leaves of eucalyptus: A chemotaxonomic survey—II. |year=1967 |journal=Phytochemistry |pages=259–274 |last1=Hillis |first1=W.E.|issue=2 |bibcode=1967PChem...6..259H }}</ref> and the ratio of the amount of [[leucoanthocyanin]]s varies considerably in certain species.<ref>{{cite journal |doi=10.1016/S0031-9422(00)83632-8 |volume=5 |title=Variation in polyphenol composition within species of Eucalyptus l'herit |year=1966 |journal=Phytochemistry |pages=541–556 |last1=Hillis |first1=W.E.|issue=4 |bibcode=1966PChem...5..541H }}</ref>

===Related genera===
[[File:Tasmania logging 16 Styx a tree in danger.jpg|thumb|right|upright=0.9|''Eucalyptus regnans'' exceeding {{Convert|80|m|ft}}, in an area of extensive logging, Tasmania]]
''Eucalyptus'' is one of three similar [[genera]] that are commonly referred to as "[[eucalypt]]s", the others being ''[[Corymbia]]'' and ''[[Angophora]]''. Many species, though by no means all, are known as gum trees because they exude copious [[Kino (gum)|kino]] from any break in the [[bark (botany)|bark]] (e.g., [[Eucalyptus haemastoma|scribbly gum]]). The generic name is derived from the [[Ancient Greek|Greek]] words ευ (''eu'') "well" and καλύπτω (''kalýpto'') "to cover", referring to the [[Operculum (botany)|operculum]] on the [[Sepal|calyx]] that initially conceals the [[flower]].<ref>{{cite book |url=https://books.google.com/books?id=NJ6PyhVuecwC |title=The Names of Plants |first=D. |last=Gledhill |edition=4 |publisher=Cambridge University Press |isbn=978-0-521-86645-3 |year=2008 |page=158 |access-date=2013-11-22}}</ref>