Costus asplundii Costus talbotii

Above left is the beautiful neotropical species Costus asplundii. Above to the right is the African species Costus talbotii.

GENUS COSTUS


Costus is the largest and most diverse genus in the plant family Costaceae. There are currently 52 accepted species known in the neotropics and 24 species in Africa (Maas 2016). When our revision to the monograph on new world Costaceae is published, there will be about 18 new species of neotropical Costus added and several other new combinations or splits in varieties bringing the total of neotropical Costus species to 75. In English speaking areas they are known as "spiral gingers" and as "caƱa agria (sour cane)" in most Spanish speaking areas. They are not true gingers as this plant family was split off from the true ginger family about 50 years ago.

As a large genus with a wide geographical distribution, they are quite diverse in form. Some Costus species have small tubular flowers, others have broad spreading labellums. Some have foliaceous appendages to the bracts, some are lacking the appendages and are shaped more like a cone. Some plants flower terminally at the top of the leafy stems and some flower below on leafless or nearly leafless stems - sometimes with both flowering forms on the same plant. Some Costus species lie flat on the ground and some are as tall as 5 meters (15 feet) or more. The showy bract colors are green, red or yellow and the flower colors can be almost pure white, red, yellow, orange, pink - with shades that approach nearly any color but blue or black.

As garden plants, most are restricted to frost-free climates, but there are about 8 species that are reliably hardy and can be grown outdoors in areas with light frost. A few of them are compact enough to be grown in pots and stored indoors over winter but most are over two meters tall at maturity. Generally Costus are shade plants that grow in the forest understory in their native habitats, but many will tolerate full sun or nearly full sun given sufficient moisture.

Here I have already broken my own rule and tried to generalize these plants when in reality they are so diverse that it is impossible, so please click on the species links below to read in more detail about individual taxa of this wonderful genus.

SPECIAL NOTE REGARDING THIS REVISION PAGE
The new species names and taxonomic changes shown here have not yet been published and are not yet established. An article has been published using the new names in Frontiers in Plant Science on September 8, 2022, A phylogenic tree showing the evolutionary relationship between species of neotropical Costus can be downloaded here.

The species names are listed here in order showing first the new species, secondly the taxonomic status changes, thirdly those species currently ACCEPTED and not changing, then other categories such as cultivar names, synonyms, etc.
You can use your browser FIND command (usually control f) to quickly find a name listed on this page.


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February 3, 2023 - Until the PHP code on my website can be updated, most of these pages will not function. I have created a temporary list of all Costaceae species with links to my field observations and photos. To open this page, click the link below..

LIST OF SPECIES WITH LINKS TO FIELD OBSERVATIONS AND PHOTOS

CONTINENT CURRENT NAME PROPOSED NAME STATUS DATASHEET FIELD OBSERVATIONS PHOTO PAGE