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Inflorescence and Floral development in Orchidantha maxillarioides (Lowiaceae).

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

Abstract: The inflorescence of Orchidantha maxillarioides is similar to a richly branched, polytelic truncate synflorescence. It consists of two to three paracladia borne in the axils of the uppermost phyllomes of the shoot. Each paracladium consists of six bracts. The lowermost bract is the sterile prophyll. The second and third bracts subtend paracladia of the next higher order. The fourth bract subtends a single flower. The fifth and sixth bracts are initiated but do not complete development. Initiation of the paracladia in the axils of bracts 2 and 3 is acropetal, but their differentiation is basipetal. The flowers are trimerous, with a perianth differentiated into sepals and petals. One petal is enlarged to form a labellum. There are five stamens, one inserted opposite each perianth member except the labellum. The ovary is inferior and is closed by a prolongation many times the length of the locular region of the ovary. Floral organ initiation begins with the posterior sepals. The anterior sepal is formed slightly later, at the same time as the initiation of the corolla. The anterior petals arise from primordia that produce only these organs, while the posterior petal (the labellum) arises from a common petal/stamen primordium. The petal/stamen primordium separates into the labellum and the two posterior outer stamens. The anterior outer stamen is initiated slightly later, in the region between the anterior petals. Throughout these stages a floral cup forms below the floral parts. The two inner stamens are initiated simultaneously on the inner surface of this cup, near the insertion of the anterior petals. Three gynoecial primordia are initiated at the top of the floral cup in the region that will form the prolongation. The primordia extend proximally to form the ovary proper and distally to form the style and stigma. The prolongation is formed through intercalary growth. Based on structural and functional similarities in the prolongation and inflorescence, we support placement of the Lowiaceae as the sister group of the Strelitziaceae.

Additional Information

Publication
International Journal of the Plant Sciences 156: 159-171
Language: English
Date: 1995
Keywords
Orchidantha maxillarioides