{{Short description|Genus of flowering plants}} {{Automatic taxobox |image = Micromelum minutum flowers and foliage.jpg |image_caption = ''Micromelum minutum'' |taxon = Micromelum |authority = Blume<ref name="APC">{{cite web |title=''Micromelum'' |url=https://biodiversity.org.au/nsl/services/apc-format/display/72616|publisher=Australian Plant Census |accessdate= 28 July 2020}}</ref> |subdivision_ranks = Species |subdivision = See text |synonyms_ref = <ref name="APC" /> |synonyms = ''Aulacia'' <small>Lour.</small> }}

'''''Micromelum''''' is a genus of eight species of flowering plants in the family Rutaceae.

==Description== The genus includes evergreen and deciduous shrubs and trees. The leaves are glandular and aromatic, containing essential oils. They are alternately arranged. They are usually pinnate, divided into up to 23 leaflets, except for ''M.&nbsp;diversifolium'', which sometimes has undivided leaf blades. The leaflet edges are smooth or toothed. There are sometimes glandular stipules. The inflorescence is a large panicle, sometimes flat-topped like a corymb, growing from the {{botanygloss|axil|leaf axils}} or at the ends of branches. The flowers have five narrow petals in shades of green, white, or yellow, borne in a hairy, cup-like {{botanygloss|calyx}} with five lobes or five separate sepals. The odour of the flowers has been described as "malodorous" and "foetid".<ref name="FloraBase" /> There are ten stamens and one to five styles. The genus is noted for the unusual curving or twisting of the chambers in the ovary. The fruit is a berry up to {{cvt|1|cm|1}} long. It is yellow, orange, or red, and sometimes fleshy, but it lacks the pulp present in some related fruits, notably citrus. The peel is gland-dotted. Each fruit has one to three seeds.<ref name=swing/><ref name=china/><ref name="FloraBase" />

The plants vary in form, with ''M..&nbsp;hirsutum'' being a low shrub sometimes less than {{cvt|1|m}} tall and ''M. integerrimum'' being a tree which can exceed {{cvt|9|m}} in height.<ref name="key">{{cite book |last1=Burke |first1=J. Henry |last2=Swingle |first2=Walter T. |last3=Reece |first3=Philip C. |last4=Hodgson |first4=Robert W. |last5=Lawton |first5=Harry W. |editor1-last=Reuther |editor1-first=Walter |editor2-last=Webber |editor2-first=Herbert John |editor3-last=Batchelor |editor3-first=Leon Dexter |title=The Citrus Industry |date=1967 |publisher=University of California Press |location=California |edition=Revised |url=http://websites.lib.ucr.edu/agnic/webber/Vol1/Images/Key3.htm |archive-url=https://web.archive.org/web/20150227030905/http://websites.lib.ucr.edu/agnic/webber/Vol1/Images/Key3.htm |archive-date=27 February 2015}}</ref><ref name=swing/>

==Taxonomy== The genus ''Micromelum'' was first formally described in 1825 by Carl Ludwig Blume in ''Bijdragen tot de Flora van Nederlandsch Indie'' and the first species described was ''Micromelum pubescens'', now regarded as a synonym of ''Micromelum minutum''.<ref name="APC1">{{cite web |title=''Micromelum minutum'' |url=https://biodiversity.org.au/nsl/services/apc-format/display/72629|publisher=Australian Plant Census |accessdate= 28 July 2020}}</ref>

There are several subfamilies in the citrus family, with genus ''Citrus'' classified in the Aurantioideae. ''Micromelum'' belongs to the other tribe in this subfamily, Clauseneae. It is the only genus of the subtribe Micromelinae that are known technically as the "very remote citroid fruit trees".<ref name=swing>Swingle, W. T., rev. P. C. Reece. [https://web.archive.org/web/20110719055159/http://websites.lib.ucr.edu/agnic/webber/Vol1/Chapter3.html Chapter 3: The Botany of ''Citrus'' and its Wild Relatives.] In: ''The Citrus Industry'' vol. 1. Webber, H. J. (ed.). Berkeley: University of California Press. 1967.</ref>

''Micromelum'' includes eight species distributed in Asia, Australia, and the Pacific Islands.<ref name=FloraBase>{{FloraBase|name=''Micromelum''|id=22447}}</ref><ref name=china>[http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=120579 ''Micromelum''.] Flora of China.</ref><ref name=ucr>[http://www.citrusvariety.ucr.edu/citrus/citrus.html Citrus Variety Collection.] College of Natural and Agricultural Sciences. University of California, Riverside.</ref>

===Species list=== The following is a list of species and varieties accepted at the Plants of the World Online as at July 2020:<ref name="POWO">{{cite web |title=''Micromelum'' |url=https://powo.science.kew.org/results?q=Micromelum |publisher=Plants of the World Online |accessdate=28 July 2020}}</ref> * ''Micromelum compressum'' <small>Blanco</small> – Vietnam * ''Micromelum coriaceum'' <small>Seem.</small> – New Caledonia * ''Micromelum diversifolium'' <small>Miq.</small> * ''Micromelum glanduliferum'' <small>B.Hansen</small> – Laos, Thailand * ''Micromelum hirsutum'' <small>Oliv.</small> – Bangladesh, Laos, Malaya, Myanmar, Vietnam * ''Micromelum integerrimum'' <small>(Roxb. ex DC.) Wight & Arn. ex M.Roem.</small> – Andaman Is., Cambodia, China South-Central, China Southeast, East Himalaya, Hainan, Laos, Myanmar, Nepal, Philippines, Thailand, Tibet, Vietnam * ''Micromelum minutum'' <small>(G.Forst.) Wight & Arn.</small> – Assam, Bangladesh, Cambodia, China South-Central, China Southeast, Fiji, Hainan, Laos, Lesser Sunda Is., Malaya, Myanmar, New Caledonia, Niue, Samoa, Solomon Is., Thailand, Tonga, Vanuatu, Vietnam, Wallis-Futuna Is., Australia ** ''Micromelum minutum'' var. ''ceylanicum'' <small>B.C.Stone</small> – Sri Lanka * ''Micromelum scandens'' <small>Rech.</small> – Bismarck Archipelago

==Chemistry== ''M. minutum'' is used as a traditional medicine in Fiji, and in Malaysia it is used to treat fever and ringworm.<ref name=ito>Ito, C., et al. (2000). [http://cpb.pharm.or.jp/cpb/200003/c03_0334.pdf Chemical constituents of ''Micromelum minutum''. Isolation and structural elucidation of new coumarins.] ''Chemical and Pharmaceutical Bulletin - Tokyo'' 48(3), 334-38.</ref> ''M. integerrimum'' has been used in China to treat dysentery and arthritis.<ref name=he>He, H. P., et al. (2001). [http://210.72.88.198:8080/bitstream/151853/4392/1/201201070048.pdf Three new coumarins from ''Micromelum integerrimum''.]{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }} ''Chinese Chemical Letters'' 12(7) 603-06.</ref>

The chemistry of these plants has been studied, with several known and new coumarins isolated.<ref name=ito/> One such coumarin from ''M. integerrimum'', micromelin, appears to have anticancer properties.<ref name=he/>

==References== {{Reflist}}

{{Taxonbar|from=Q9032437}}

Category:Aurantioideae genera Category:Aurantioideae Category:Taxa named by Carl Ludwig Blume