This article describes the anatomical features of leaves of seventeen species of Aigeiros and Cathay Poplars. Of the 17 species examined here, 5 (Populus dtltoides Bartr. cv. ’Lux’ (ex. I-69/55); P.deltoides Bartr. var. deltoides cv. ’Harvard’ ( I-63/51); 872; 8885 and 890) have distinctly isolateral leaves, 5 (I-69 × Populus nigra cv. Blane de garonne; Shan Hai Guan Poplar x I-63 ;P. × eurameri-cana (Dode) Guinier (ex. I-214) × I-63; P- × euramericana (Dode) Guinier cv. ’san Martion’ (ex. I-72/58) × I-63; and I-72 show a tendency to be isolateral. 3 (P. simonii Carr; P. maximowiczii Henry.; Populus nigra cv Blanc de garonne.) have dorsi-vcntral leaves, and 4 (I-69 × P. simonii Carr., I-69 × P. maximowiczii Henry.; Shan Hai Guan Poplar and I-214) show a tendency to be dorsi-ventral. This article also analyzes the hereditary properties of, the hybrid filial generation and discusses the relationship between the features of leaves and the genetic factors, attempting to provide on anatomic theoretical basis for the selection and breading of superior clones.