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Poaceae family

Cenchrus echinatus
, Sp. Pl. 2: 1050.  1753.

Zèb kolan   
Indigenous very common pantropical herb of open dry areas, especially coastal.

FLA also lists Cenchrus brownei and Cenchrus incertus as being present in St. Lucia. I have sent off several collections and all have been determined to be Cenchrus echinatus. The herbarium specimens of the two other species appear to me to be Cenchrus echinatus.
Inflorescence variable in colour.