Structure of Phaseolus lunatus Testa at its Central Point

Tadeusz Aniszewski1*, Anna-Liisa Karttunen2, And Heikki Hyvarinen3

1Laboratory of Applied Botany, 2Laboratory of Histology, 3Laboratory of Transmission Electron Microscopy, Department of Biology, University of Joensuu,
P. O. Box 111, 80101 Joensuu, Finland

*e-mail: Tadeusz.Aniszewski@joensuu.fi
Received November 2, 2005; revision accepted January 30, 2006

In the Phaseolus lunatus seed, the strata and cells of the testa at the central point of the broad side are described. The proposed regionalization and the central point technique makes it possible to define precisely each site in the testa. Exo-, meso- and endotesta are found to be basic strata in the central point studied. The exotesta is divided into cuticle, palisade and crushed cell layers. The cuticle layer is irregular and noncellular. The palisade cells are exoepidermal sclerenchyma and the crushed cells are former exoepidermal cells. The mesotesta is composed of hourglass cells, called stapes cells here because their form resembles stapes, and crushed cells. The stapes cells are parenchyma. The endotesta is composed of support tissue, three crushed cell layers, phloem, xylem and testa bottom. The endotesta adjoins the cotyledon.

Key words: Phaseolus lunatus, endotesta, exotesta, Malpighian cells, mesotesta, legume, testa structure.