1. Karyological studies were made on five hyper-triploid garden varieties of Hyacinthus orientalis, of which the chromosome numbers of Mad. Banchrope (2n = 26), Pearl (2n = 26) and Johanna (2n = 28) were determined for the first time.
2. The karyotypes of the five verieties studied can be formulated as follows :
Garden varieties Karyotypes (Additional chrom.)
Ostara 2n = 25 = 12V+12J+ (J)
Mad. Banchrope 2n = 26 = 12V+ 12J+ (2V)
Pearl 2n = 26 = 12V+12J+(2V)
L'Innocence 2n = 27 = 12V+12J+ (3V)
Johanna 2n = 28 = 12V+ 12J+ (3V+J)
3. Among the five varieties studied was observed a slight morphological variation of chromosomes.