Chromosome Numbers in Oncidium Alliance

1. Somatic chromosomes were counted by the root squash in 15 genera, in which 97 species and varieties, and 40 hybrids are included. The hybrids are 14 kinds of genus combinations in the Oncidium alliance.2. New numbers (2n) were added in species: 2n=24, 26, 30, 32, 37, 40, 60, 84, 133 and 168 (Tables 1-3).3. The basic numbers of chromosomes in the Oncidium alliance may be 5 and 7.4. Most of the hybrids studied showed the sum of their parents' chromosome numbers though some hybrids have not (Table 4).5. The chromosome numbers found in the hybrids are as follows (Table 4): 2n=28, 32, 34, 40, 41, 42, 44, 49, 50, 56, 58, 59, 60, 61, 76, 80, 84 and 112.6. Karyotypes could be analysed in some species and hybrids. Generally only constrictions can be seen, and trabants, seta, etc. can not easily be recognized.