Micropropagation and medicinal properties of Barleria greenii

1.3 Distribution, morphology, uses and conservation status of the studied
plant species
1.3.1 Barleria greenii
The genus Barleria, belonging to the Acanthaceae family, is a large genus of
herbs and shrubs comprising about 300 species worldwide (MAKHOLELA et al.,
2003). The richest representation is in Africa where there are two centers of
diversity, one in tropical east Africa (about 80 species) and the other in southern
Africa (about 70 species) (BALKWILL and BALKWILL, 1998). Most species in
this genus show a high degree of regional endemism. For example, the Indian
subcontinent, West Africa, southern Africa and East Africa are reported to have
75, 72, 65 and 56% endemism, respectively (BALKWILL and BALKWILL, 1998).
Barleria greenii M.-J. Balkwill & K. Balkwill is one such species endemic to South
Africa. The first population of B. greenii was discovered in 1984 by Dave Green, a
farmer and amateur botanist from the Estcourt district of Natal (BALKWILL et al.,
1990). It is extremely localized and extremely restricted in distribution, occurring in
eight localities on three farms near Estcourt, South Africa (MAKHOLELA et al.,
2003). Plants belonging to this species are found in open, rocky areas on
moderately sloping north-facing aspects, mostly between the 1200 m and 1260 m
contours (BALKWILL et al., 1990). The ballistic seed dispersal occurring over
short distances further affects its distribution such that long-range dispersal to new
suitable habitats occurs rather rarely (BALKWILL et al., 1990).
Barleria greenii is a perennial, profusely branched woody shrub (Figure 1.1) up to
1.8 m high (BALKWILL et al., 1990). Its growth form is affected by light intensity
and the frequency with which its habitat area is burnt (BALKWILL et al., 1990).
BALKWILL et al. (1990), for example, observed that plants growing in the shade
are much less robust and have broader leaves than those growing in full sun. They
noted that plants burnt less often are extremely robust, woody, attaining heights of
almost 2 m, whereas those burnt often are less robust, attaining a greater
diameter with more vigorous branching but a height of only 0.8 m. Barleria greenii
flowers from mid-to late summer, usually over a period of a few weeks
(MAKHOLELA et al., 2003). The attractive flowers, ranging from pure white to
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