The phyllotaxy of Costus (Costaceae)

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Bruce K. Kirchoff, Emeritus Professor (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:

Abstract: The spiromonostichous phyllotaxy of Costus, and other Costaceae, is characterized by low divergence angles, often as low as (30°—) 50°. This constrasts with the main series Fibonacci (divergence angles ap-proximating 137.5°) or distichous phyllotaxy found in all other Zingiberales. A morphological and devel-opmental study of three species of Costus revealed a number of facts about this unusual phyllotactic pattern. In C. scaber and C. woodsonii the divergence angles gradually change along a shoot, from 140°-100° in the region of the cataphylls to 60°-45° in the inflorescence. In C. cuspidatus, the divergence angles change from 40°-100° in the cataphyll region to ca. 137° in the inflorescence. In all three species, the cataphylls and foliage leaves have tubular sheaths, while the inflorescence bracts are nonsheathing. Thus, spiromo-nostichy is only loosely correlated with closed leaf sheaths.

Additional Information

Botanical Gazette 151: 88-105
Language: English
Date: 1990

Email this document to