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Datasheet for Costus guanaiensis var. macrostrobilus

Plant Datasheet for Costus guanaiensis var. macrostrobilus

CLICK HERE for a detailed botanical description and identification key for this species (opens in new window).

BOTANICAL NAME: Costus guanaiensis var. macrostrobilus
FORMAL SCIENTIFIC NAME: Costus guanaiensis Rusby
CONTINENT: Neotropical
Costus argenteus, Costus freidrichsenii, Costus macrostrobilus, Costus scaber, Costus villosissimus,

Paul Maas distinguishes var. macrostrobilus as follows: "Sheaths glabrous, rather densely puberulous to villose. Upper side of the leaves densely or rarely sparsely strigose [stiff, appressed hairs], somewhat scabrid to the touch, lower side densely villose to puberulous. Bracts glabrous to puberulous." I have had difficulty differentiating this variety from var. guanaiensis. He further describes this variety as producing its inflorescence terminally on a leafy stem - not basal - whereas var. guanaiensis can produce either type of inflorescence. So I am assuming if the hairs are not brown, but are appressed on the upper side of the leaves and feel somewhat scabrous (rough like sandpaper when brushed in one direction), then it may be var. macrostrobilus.

According to Maas in the Flora Neotropica, the distribution of var. macrostrobilus is more prevalent in Central America and northwestern South America extending to the Pacific side of Colombia (Depts of Chocó, Antioquia and El Valle (a/k/a Valle de Cauca) and Ecuador (Esmeraldas-Los Rios). However, there are also collections that Maas determined as var. macrostrobilus in Venezuela, Guyana, Brazil and Peru. Geographically, there is much overlap between this variety and var. guanaiensis.

Many examples of Costus guanaiensis I have seen in Costa Rica, Panama and eastern Ecuador do NOT seem to have upper leaf surfaces scabrid. I have been unable to find any plant that I can reliably identify as var. macrostrobilus based on the leaf indument in these countries. In checking GBIF records for collections that have been determined by Paul Maas to be var. macrostrobilus, they have come from the following countries: 6 from Belize, 1 from Brazil, Acre, 2 from Colombia, 6 from Costa Rica including 4 in Puntarenas/Osa Peninsula, 1 in Ecuador, Esmeraldas, 1 in Guyana, 6 in Nicaragua, 19 in Panama from Bocas del Toro on the western Caribbean side to Darién on the Pacific side, 3 in Peru including Loreto (Maynas), and 10 in Venezuela.

In checking GBIF records for collections determined by Paul Maas as var. guanaiensis I found the following: 2 from Bolivia, 9 from Brazil, Acre, 6 from Costa Rica (central part, San Jose and Cartago), 3 from Panama, including La Fortuna area, and 21` from Peru, mostly Loreto and Madre de Dios.

So it would seem that these two varieties are pretty much intermingled, and considering the natural proclivity of Costus hairiness to be variable, I have some real doubts about the value in separating these two varieties - at least based on the minor differences in the hairs on the leaves.

R2930 was supposed to be this variety but did not survive.


Laguna de Cube, La Y, Esmeraldas Province, Ecuador, Latitude 0.392, Longitude -79.645, at 330 meters elevation.

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