scipsy:

Longitudinal section of developing caryopsis of maize ancestor, teosinte (via Botanical Society of America)

About the Image

Longitudinal section of developing caryopsis of maize ancestor, teosinte (Zea mays ssp. parviglumis, caryopsis diameter cca. 3 mm). Teosinte plants differ significantly from domesticated maize Zea mays ssp. mays. Teosinte plants have many lateral branches with terminal male inflorescences, which closely resemble maize tassels, and small female inflorescences or “ears”, which are very different from maize ears, in leaf axils. Kernels in the teosinte ears are arranged in two rows and enclosed in hard cupulate fruitcases (fruitcases turn brown if they contain fertilized kernels), and they disarticulate at maturity. In contrast with the highly dissimilar morphology of the teosinte caryopsis, various cellular processes in the filial seed inside the glumes are remarkably similar to maize (which lacks prominent glumes). Endosperm cells in the developing teosinte kernels undergo endoreduplication—multiple duplications of the whole nuclear genome without intervening cell division, resulting in endopolyploid cells. The colored bubbles superimposed on a section of the developing teosinte kernel represent the nuclei in the seed (embryo and endosperm) and in the pericarp (mature ovary wall). Different classes of endopolyploidy are represented by different colors, and the size of the bubbles is proportional to the ploidy level of the nuclei.

For further detail, see: Dermastia et al.—A cellular study of teosinte Zea mays subsp. Parviglumis (Poaceae) caryopsis development showing several processes conserved in maize Volume 96, Issue 10, pages 1798–1807. Photo credit: Aleš Kladnik.