Indument and trichomes in the characterization of a group of nine species of Mortoniodendron (Tiliaceae)

Abstract

THE INDUMENT AND TRICHOME MORPHOLOGY IN LEAVES AND ENDOCARP FOR 9 SPECIES OF MORTONIODENDRON (TILIACEAE) WERE STUDIED. THE DISTRIBUTION AND THE TYPE OF TRICHOMES WERE ESTABLISHED ACCORDING TO THEIR FORM, SYMMETRY, SIZE, AND DENSITY USING SCANNING ELECTRON AND OPTICAL MICROSCOPY. TWO CATEGORIES FOR THE DISTRIBUTION OF TRICHOMES WERE DEFINED IN THE LEAVES AND THE ENDOCARP. IN THE CASE OF THE LEAVES, 7 SPECIES HAVE AXILLAR INDUMENT AND IT IS GLABRESCENT IN 9, WHILE IN THE ENDOCARP 5 SPECIES SHOW GLABRESCENT AND OTHERS GLABROUS. FOUR TYPES OF TRICHOMES WERE RECOGNIZED: ACICULAR WITH A SINGLE ARM, FASCICULATE WITH 2-5 ARMS, STELLATE WITH 3-18 ARMS, AND UNI OR MULTICELLULAR CAPITATE. ACICULAR AND FASCICULATE TRICHOMES PREVAIL IN M. COSTARICENSE, M. HIRSUTUM AND M. VESTITUM. STELLATE TRICHOMES ARE PRESENT IN ALL THE SPECIES, BUT 4 CATEGORIES ARE DISTINGUISHED ACCORDING TO SIZE AND NUMBER OF ARMS. ONLY M. PALACIOSII AND M. RUIZII POSSESS CAPITATE TRICHOMES. IN THE ENDOCARP STELLATE TRICHOMES PREVAIL, EXCEPT FOR M. VESTITUM WITH LONG FASCICULATE TRICHOMES. THE TAXONOMIC USEFULNESS OF THE RESULTS IS DISCUSSED AND A KEY TO IDENTIFY THE SPECIES IS PROVIDED.