THE SECRETORY TISSUE OF ALOES AND THEIR ALLIES

Abstract

ABSTRACT The presence of thin-walled parenchymatous cells in the inner bundle sheath of species of the liliaceous genera Aloe, Chamaealoe, Astroloba, Lomatophyllum, Gasteria, Haworthia, Asphodeline, Asphodelus, Bulbine, Eremurus and Trachyandra was observed and described. Some species, however, have lignified sclerenchymatous cells in this position and this is general in Kniphofia. Cells in this region produce a secretion in the form of a copious exudate in many species of Aloe, or much sparser contents in the case of related genera. The leaves of most species contain small amounts of anthraquinones, while the related anthrone-C-glycosides accumulate in others. A wide range of other phenolic substances occurs, recognized as distinct zones on thin layer chromatograms, but mainly consisting of unidentified compounds. It is not certain if synthesis occurs in the thin-walled bundle sheath cells or if these have only a storage function. Another layer of rather smaller parenchymatous cells in the outer bundle s...