This page contains photos and description of a species, form or cultivar of Costaceae.

Gingersrus Database Taxon ID 4863

Costus comosus


OLD NAME: Costus comosus - bakeri form

NEW NAME: Costus comosus

NAME CHANGE NOTES: This is currently a separate formal variety of Costus comosus but is proposed to be merged with the species.

FULL SCIENTIFIC NAME:

STATUS : distinct form

CONTINENT: Neotropical

FIELD OBSERVATIONS:(If field observations are available, you can click on the link to open in a new window.)
FIELD OBSERVATIONS

PHOTOS:(If photos are available, you can click on the link to open in a new window.)

SYNONYMS:


BOTANICAL NOTES:
Costus bakeri was first published in 1904 in Vol. IV of Engler's Das Pflanzenreich, described as a new species by Karl Schumann. The type was a collection in 1892 in Guatemala by John Donnell Smith, which flowered in February 1892. It is significant that Schumann also included the species Costus comosus in Das Pflanzenreich, and therefor considered them as separate species. They were considered to be separate until 1972 when Paul Maas in his monograph reclassified it was a variety of Costus comosus, differentiating the two varieties by the indumenta on the upper side of the leaves and the bracts. In our upcoming revision to new world Costaceae, Dr. Maas has proposed to merge this variety into Costus comosus, stating that: "As we found many intermediates between var. comosus and var. bakeri we herewith unite the 2 the varieties of this species. This whole complex clearly needs, however, a thorough study in the field."

Costus bakeri as it was previously known as a separate species, was only found along the Pacific coast of southern Mexico, Guatemala and El Salvador. It was only after the change to list it as a variety of Costus comosus that collections were determined as such (based on the indumenta) in area to the south as far south as Santa Cruz, Bolivia. In Chiapas, Mexico, it is only found in the mountains at elevations of 600-1300 meters around the base of the Volcán Tacaná. Collections in Guatemala and El Salvador likewise have been found in volcanic regions.

In 2014 I explored the region around Tapachula, Chiapas, Mexico to see what this form looked like in the living plants. I found that it is much taller than the other forms of C. comosus, with mature plants usually reaching 3 to 4 meters in height. The shape and color of the bract appendages are distinctly different from other forms of C. comosus as can be seen in my photos on Inaturalist and on the collections pages at the links below under Accessions. A thumbnail page showing photos of this plant can be found at http://www.gingersrus.com/images/Comosus_Chiapas

The dry season is very much separated from the rainy season along the Pacific coase of Central America, in most areas from about November to April. I completed a study of all Costus species to determine the flowering periods of each species and found that this is one of only three species that I could identify that flowers only in the dry season. This also (in my opinion) also differentiates this from other Costus comosus forms.

A partial phylogeny was completed by Eugenio Valderrama and his associates in the Chelsea Specht Lab at Cornell University and was published in the journal Frontiers in Plant Science in September 2022. DNA has been extracted from samples across the entire range of Costus comosus, and this bakeri form was found to be in a completely separate clade from the other forms. As additional samples are added to the phylogeny, it will be interesting to see how many distinct lineages they are found in.

In my opinion there is sufficient data to reinstate this as a separate, accepted species Costus bakeri and further study might determine other separate taxa within the Costus comosus complex.

NOTE: The plant commonly sold in the USA and displayed in many botanical gardens as "Costus barbatus" has been determined to be Costus comosus - not barbatus, and it fits best as var. bakeri. It is not the same as this form from the Pacific coast of Meso-america. The common cultivated plant incorrectly known as "Costus barbatus" can be found on a separate page at PID 7586.

HORTICULTURAL NOTES:


ACCESSIONS:Click links (if any) to see details of individual collections. R3312- R3313- R3315-


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Photos (if available) of Taxon ID 4863
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Costus comosus type specimen - Click to see full sized image
Photo# 475 Accession# R0
Costus comosus type specimen


Costus comosus, bakeri form, photo from Skinner R3312, collected Chiapas, Mexico - Click to see full sized image
Photo# 178 Accession# R3312
Costus comosus, bakeri form, photo from Skinner R3312, collected Chiapas, Mexico


Costus comosus, bakeri form, photo from Skinner R3312, collected Chiapas, Mexico - Click to see full sized image
Photo# 179 Accession# R3312
Costus comosus, bakeri form, photo from Skinner R3312, collected Chiapas, Mexico