Developmental evidence helps resolve the evolutionary origins of anther appendages in Globba (Zingiberaceae)

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 )
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Abstract: Globba is one of the largest genera in the primarily tropical Zingiberaceae. The number of anther appendages is highly diagnostic and has been used along with molecular characters to define subgenera and sections. Four main types of anther morphology are recognized: without appendages and with two, four and six appendages. The six-appendaged anthers are reported here for the first time. Appendages arise from two dorsal ledges that flank the broad connective. Development of two-appendaged and four-appendaged species differs from inception. Previous suggestions that either the proximal or distal appendages of four-appendaged anthers have been lost in two-appendaged species are thus not supported. Early development of six-appendaged anthers is similar to that of four-appendaged species, but two additional, small appendages develop on the ledges between the first-formed appendages. This yields three appendages on each side (six overall). The four appendages of G. geoffrayi differ from all other species in having distal appendages that are much smaller and develop later than the proximal appendages. Development thus suggests that the state in G. geoffrayi evolved from a two-appendaged ancestor. Incorporating this information into a phylogenetic character plot of the number of appendages shows that the possession of two appendages is the most likely plesiomorphic state of the genus, although support for this hypothesis is weak. Our study clarifies the origin and complexity in the development of anther appendages in Globba and highlights their significance in infrageneric relationships in Globba. Two appendages have probably likely arisen at the base of Globba, linked with the presence of a prominent ledge, with variable extensions and reductions of the number of appendages in the various subgenera and sections.

Additional Information

Botanical Journal of the Linnean Society, Volume 189, Issue 1, 1 January 2019, Pages 63–82
Language: English
Date: 2019
connective, floral development, Globbeae, phylogeny

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