Family Iridaceae
Distribution and HabitatMoraea polystachya is
widespread in central South Africa and Namibia, but its range overlaps that of
M. venenata in Namibia and Northern Cape, South Africa. The average
annual rainfall ranges from 100 to 700 mm, and is probably considerably less in
a 'normal' year. In part of their common range, the sparse rainfall occurs in
summer, while the remainder of the range receives rain in winter. The habitat is
well-drained flats and slight slopes, with collectors often referring to the
presence of calcrete deposits. Light frost occurs, but in mid-summer (when the
plants are dormant) the temperatures may regularly exceed 40ยบ C.
EcologyAs mentioned above, in the northern part of the
common range, the plants flower mainly in autumn (March to May), but in the
south, flowering is more usual in winter (June to August) or even spring
(September, October). The complex style structure is known to be specifically
adapted for bee pollination, but unfortunately no specific observations on these
two species are available.
The plants are thought to increase in number due to overstocking of grazing
land. It is interesting that stock animals born and raised in lands infested
with these plants are able to recognize and avoid them. Cattle deaths often
occur in the winter months when there is no other fresh grazing available. The
dried plant material is also toxic and when accidentally incorporated in hay can
have disastrous results. A few cases of fatal human poisoning have been
reported, where the corms were mistaken for those of edible species, such as
Moraea fugax. The toxin has been identified as a cardiac glycoside
(heart-poison).
Uses and cultural aspectsOne label attached to a
herbarium specimen reports that the 'Hottentots plait the leaves into mats' but
this information has not been confirmed elsewhere.
The two species are economically important due to their toxicity. Southern
Africa abounds in toxic plants and much time and energy has been devoted to
identifying the plants and their toxins by such government organizations as the
Veterinary Research Institute at Onderstepoort, Pretoria.
Info: http://www.plantzafrica.com
