Cytology of woody species

Abstract

Cytological studies have been made on 59 woody species of Polypetalae. Two genera (Gynocardia odorata,n=23;Pahudia martabanica,n=12) and 9 species (Talauma candollei,n=19;Cratoxylon polyanthum,n=11;Sterculia villosa,n=20;Grewia hirsuta,n=9;Millettia brandisiana, 2n=22+0−2B;Phanera glauca,n=14;Terminalia oliveri,n=12;Psidium coriaceum, 2n=77;P. pumilum,n=11) are counted for the first time. Additional and/or varied chromosome numbers are recorded for 8 species. Presence ofB-Chromosomes has been detected inCrataeva nurvala (n=13+0−3B),Erythrina caffra (n=21+0−3B) andMillettia brandisiana (2n=22+0−2B). Existence of some multivalents in the tetraploid taxa ofEugenia jambolana (2n=44) andHydnocarpus laurifolia (2n=48) indicates their segmental alloploid nature. But the presence of cent per cent trivalents (11_III) in the triploid cytotype ofEugenia uniflora (2n=33) reveals the autotriploid nature. Presence of some univalents in diploid taxa ofMillettia brandisiana (2n=22) may be due to asynapsis and/or desynapsis. Variation in chromosome number inPMCs and some pollen sterility inHydnocarpus kurzii seems to be the consequence of cytomixis. Abnormalities in microsporogenesis in one of the cultivated trees ofFirmiana pallens (2n=40) are due to spindle irregularities.