The genus Roridula consists of but two species, off by themselves in a lonely plant family called the Roridulaceae. Looking at the plant, you might think to yourself, "Ahhh, another one of those sticky flypaper-type carnivores." But the situation is far more complicated and interesting than that. Indeed, there are those who scoff my including this in the Carnivorous Plant FAQ at all! Read on...
The two species of Roridula are found in South Africa, where they live in nutrient poor, moist locations. They grow alongside many carnivorous plants such as Drosera, and like plants in that genus, capture bugs on their sticky leaves. There is no leaf or glandular motion, the plant merely captures bugs passively. When European botanists first observed Roridula, the plants were thought to be straightforward carnivores. Ahh, but something is a little different about Roridula: unlike the herbaceous sundews, Roridula is a woody shrublet. And the plot thickens even more...
In the early 1900s, the botanist Marloth pointed out that, unlike other sticky flypaper plants that produce leaves covered by mucus glands, the leaves of Roridula are covered with resin glands. This is a key difference. Mucus is water-based, resin is not. (Did you ever try to wash pine sap off your hands just using water?) Digestive enzymes and nutrients can easily diffuse through mucus, but they cannot diffuse through resin. Therefore, bugs captured by Roridula cannot be enzymatically digested or absorbed. In a cruel summary of this situation, F.E. Lloyd discussed the noncarnivorous nature of Roridula in the same paragraphs in which he discounted the mythic "Man-eating plant of Madagascar." Times were sad for poor Roridula. Subsequent tests that demonstrated that the plants did not produce digestive enzymes seemed to permanently close the files on carnivory in Roridula.
But still, still there were those who clung to hopes that Roridula might be carnivorous. And their hope was, in time, rewarded...
Read more about Roridula at the ICPS sarracenia.com FAQ
-- Barry Rice
Roridula information on the ICPS carnivorousplants.org web site:
Seed Bank: Growing Roridula
Roridula information in the Carnivorous Plant Newsletter:
Opel, Matthew R. (2005) Roridula, a carnivorous shrub from South Africa. Carniv. Pl. Newslett. 34(4):106-110 (
Search the CPN Index and Archive for over 15 articles about Roridula.