Diplolophium africanum: A common but little-known plant on Lolldaiga Hills Ranch, Kenya
By Tom Butynski, Yvonne de Jong, Mike Roberts, and Julius Mathiu, Lolldaiga Hills Research Programme
One of most widespread, common, distinctive, and little-known plants on Lolldaiga Hills Ranch, central Kenya, is Diplolophium africanum, a member of the Carrot Family (Apiaceae = Umbelliforae). This is the only Diplolophium species in the Kenya uplands. Species in this family are aromatic, have hollow or pithy stems, and an umbel inflorescence which, in D. africanum, is ca. 35 mm in diameter. The more well-known plants in the Apiaceae include celery, parsley, parsnip, anise, caraway, coriander, cumin, dill, and fennel. Upon seeing D. africanum, one is reminded of dill or fennel.
Unlike the above-listed relatives, D. africanum is not edible to humans nor, it seems, to any vertebrates except, perhaps donkeys (which are rumoured to eat small amounts). On Lolldaiga, sheep, cattle, and wild large herbivores graze around D. africanum, leaving the plant untouched…or nearly so. As such, this 2-3 m high plant becomes particularly dominant and noticeable as the long-dry season advances and as it changes colour from green to bright yellow.
Although D. africanum is wide-spread in Africa, and locally abundant in Kenya in upland grassland, wooded grassland, and woodland edges, it remains poorly-known—so poorly-known that it does not have an English common name. The Maa name for this plant is ‘daiga’ (or ‘daika’). It is, apparently, this species that led the Masai to give the name ‘Lolldaiga’ to these hills. What is known is that the leaf oil holds more than 24 compounds, some with insecticidal, antimicrobial, antifungal, and/or antiradical activities. Still, on Lolldaiga, the larvae of at least a few species of moth occur on D. africanum, and the adults and larvae of a large carpenter bee Xylocopa hottentotta and a small carpenter bee Ceratina sp. (identifications by Dr. Dino Martins) inhabit the dry stem.
Xylocopa hottentotta bore holes into dry D. africanum stems to construct nests. Each nest has a single entrance. Species within the genus Xylocopa are solitary and do not produce honey. Nonetheless, they are important pollinators of many plants, including crops.
All Xylocopa spp. buzz loudly when their nest is disturbed. Thus, nests of X. hottentotta in D. africanum are readily located simply be hitting the plant sharply, but lightly, with a finger or stick.
In East Africa, Xylocopa spp., and other species of bees, are threatened by habitat degradation and loss as a result of agricultural activities, and by herbicides and insecticides (BioNET-EAFRINET keys.lucidcentral.org).
There is an unidentified toxin in D. africanum; ingestion of large amounts of green leaf leads to shortness of breath (dyspnea), salivation, abdominal pain, staggering, and death in sheep, cattle and, perhaps, all mammals. Nonetheless, people in Ethiopia sniff the fresh, unprocessed, leaves to treat headache, and give the smashed leaves orally with water in an attempt to treat rabies.
On Lolldaiga, D. africanum is common over large areas that might otherwise produce food for livestock and wild vertebrates, particularly large mammals. A research priority on Lolldaiga is to study the ecology of D. africanum in order to understand its role in the Lolldaiga Hills ecosystem.
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