Cytological Investigation of Macaranga in Comparison to Mallotus (Euphorbiaceae) in Thailand

Abstract

Eight species of Macaranga (Euphorbiaceae) in Thailand were investigated cytologically. The results indicated that, for all species, their pollen mother cells have 2n = 22 and x = 11 consistently. Chromosomes are very well stained with propionocarmine and highly distinctively paired as bivalents at
diakinesis and separated to 11:11 at anaphase I. Bivalent length was found to be in the range of 1.3 to 6.0 µm in pollen mother cells of about 8.7–28.0 µm. Hence Macaranga species may be fertile in the wild. From a cytological point of view, Macaranga  resembles Mallotus in chromosome numbers and stainability but differs in cell size. Pollen mother cells and nucleoli of Macaranga are on average smaller than those
of Mallotus. Therefore, cytological data support the distinction of these two genera. Moreover the results also pointed out that Mallotus is more variable than Macaranga