Inveed fir tree appearance is characteristic of

Anthrax bacilli is gram-positive and is found singly, in pairs or in sho chains. On gelatin stab culture, a characteristic inveed fir tree appearance is seen in the case of anthrax bacilli, with slow liquefaction commencing from the top. On blood agar, the colonies are non-hemolytic, though occasional strains produce a narrow range of hemolysis. In broth, growth occurs as floccular deposits, with little or no turbidity. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 251