Niger stems are hollow and break easily. The number of
branches per plant varies from five to twelve and in very dense plant stands fewer
branches are formed. The colour of the stem varies from dark purple to light green
and the stem is about 1.5 cm in diameter at the base. The plant height of niger is an
average of 1.4 m, but can vary considerably as a result of environmental influences
and heights of up to 2 m have been reported from the Birr valley of Ethiopia.
The niger flower is yellow and, rarely, slightly green. The heads are 15-50 mm in
diameter with 5-20 mm long ray florets. Two to three capitulae (heads) grow together,
each having ray and disk florets. The receptacle has a semi-spherical shape
and is 1-2 cm in diameter and 0.5-0.8 cm high. The receptacle is surrounded by two
rows of involucral bracts. The capitulum consists of six to eight fertile female ray
florets with narrowly elliptic, obovate ovules. The stigma has two curled branches
about 2 mm long. The hermaphrodite disk florets, usually 40-60 per capitulum, are
arranged in three whorls (Figs. 1.1 and 1.2). The disk florets are yellow to orange
with yellow anthers, and a densely hairy stigma.
The achene is club-shaped, obovoid and narrowly long (Seegeler 1983). The
head produces about 40 fruits. The achenes are black with white to yellow scars on
the top and base and have a hard testa. The embryo is white.
Niger is usually grown on light poor soils with coarse texture (Chavan 1961). It
is either grown as a sole crop or intercropped with other crops. When intercropped
it receives the land preparation and cultivation of the main crop. In Ethiopia it is
mainly cultivated as a sole crop on clay soils and survives on stored moisture. A
more detailed description on the agronomy of niger is presented under Agronomy