Studies on the floral anatomy and scent chemistry of titan arum (Amorphophallus titanum, Araceae)

Abstract

Amorphophallus titanum (Becc.) Becc. ex Arcang., the titan arum, is popularly known for having the world's largest unbranched inflorescence. The enormous flower-like inflorescence is also called 'corpse flower' or 'carrion flower' due to the characteristic putrid odor of the bloom. The present study illustrates detailed anatomy and micromorphology of the inflorescence by light and scanning electron microscopy. Collenchyma was found to be the major tissue providing mechanical support in the spathe. The appendix consisted of a dense parenchymatous cortex enclosing a hollow center traversed by loose networks of aerenchyma. Anthocyanin pigments found in the epidermises and cortical tissues imparted a purple color to various parts of the inflorescence. Two types of raphide crystals, Psychotria type and Lemna type, and cluster crystals were observed. The volatile compounds from different parts of the inflorescence were collected by a modified headspace-solid phase microextraction (HS-SPME) technique and the samples were analyzed by gas chromatography-mass spectrometry (GC-MS). The major volatile compounds found by this method included isovaleric acid (21.6%), butyric acid (17.0%), benzyl alcohol (16.2%), and g-butyrolactone (12.1%) in the appendix; g-butyrolactone (27.0%), tetradecane (13.4%), and 4-hydroxy-4-methyl-2-pentanone (10.5%) in the male flowers; tetradecane (19.9%), 4-hydroxy-4-methyl-2-pentanone (13.0%), and 3-hydroxy-2-butanone (10.6%) in the female flowers; and butyl acetate (44.5%) and 3-hydroxy-2-butanone (12.2%) in the spathe. Use of different types of SPME fibers and multiple analytical methods is necessary in order to obtain a complete picture of the volatile composition of titan arum blooms.