Barry Rice

- doing science on a terrestrial planet -

Ibicella lutea: Yet Another Note on the Carnivore from the Martyniaceae
(Bulletin of the A.C.P.S., 1994, 13:1, 6.)

I have enjoyed the recent flurry of articles regarding Ibicella lutea (for example, Bertozzi 1993; Cekic 1993; Kane 1993). But there is a small amount of misinformation in these otherwise fine articles. It is clear the plant Kane (1993) described is not Ibicella lutea (because of flower colour) but is probably Proboscidea louisianica. Seed obtained from the same source as Kane (labelled "I. lutea") germinated and subsequently flowered--revealing itself to be P. louisianica. Observations of these specimens corroborated Kane's comments on the plant's ability to capture small insects. But it will take careful work like that of Mameli (1916) to prove or disprove the possibility of a carnivorous nature for Proboscidea louisianica. Because of the continued confusion about these plants, I thought I should write a few words of clarification.

The botanical family that contains I. lutea is Martyniaceae. Various authors--as far back as Van Eseltine in 1929 and continuing to this day--have disagreed upon the structure of this family. They have shifted species from one genus to the next, and occasionally destroyed old genera or created new ones. Through the years, the carnivorous plant known today as I. lutea has been placed in three of these mutable genera--Ibicella, Martynia and Proboscidea. Fortunately there is only one plant in the Martyniaceae with the specific epithet "lutea". So if you are reading about species in this family and encounter I. lutea, M. lutea, or P. lutea, it is the plant that interests the carnivorous plant enthusiast. There are a few other genera in this family (which are not recognized by all authors), but they are unlikely to be encountered.

These genera are mostly dryland plants--several species are native to the desert I live in, and one (P. parviflora var. hohokamiana) was partially domesticated by the indigenous tribes of Arizona, USA, as a foodcrop that also had textile uses. The possibly-carnivorous plant, I. lutea, is a naturalized weed in southern California with origins in South America.

Suppose you are growing a plant from this family---how do you know if it it I. lutea, and not some noncarnivorous imposter? It is simple matter, as long as the plant is in flower. Look at the calyx ("calyx" means all the sepals). In Proboscidea the calyx consists of five sepals which are fused together for about half their lengths, forming a loose sack which encloses the corolla tube. Underneath the flower the calyx is usually slit to the base. If you removed the calyx and flattened it, you would have a palmately-lobed single structure, like the maple leaf on the Canadian national flag. In contrast, the calyx lobes of Martynia and Ibicella are completely free from each other--in these two genera, the calyx consists of five distinct sepals. At the base of the calyx you will see one or two leafy bracts. Do not mistake these for calyx lobes.

If your plant has passed the first test, so you are certain it is not Proboscidea, the next step is to determine if it is Martynia or Ibicella. This is decided by the number of fertile stamens in each flower. Ibicella has four functional stamens, but in Martynia two are not fully developed and are sterile. These sterile stamens do not support pollen-bearing anthers. Of course, the happy CPer is one who discovers he or she has Ibicella and not Martynia. As a final check look at the flower colour. As Van Eseltine (1929) wrote and Cekic (1993) maintained, the corolla tube is greenish-yellow on the outer surface, and yellow to orange-yellow on the inner surface. (This is, of course, what the name I. lutea is telling us.) The palate region of the corolla may be dotted with orange or red spots, but this is not to say the flower is reddish. The flowers are very weakly scented, while the flowers of P. louisianica (for example) are strongly musky-sour. Another species of Ibicella is I. nelsoniana (which is sometimes called Hologregmia nelsoniana). This plant is distinguished by its small and narrow floral bracts, while the bracts of I. lutea are very similar to the sepals.

A few years ago I was finally able to find a botanical garden where this plant is grown. A well-placed associate was able to obtain seed from this location but despite a year's effort, neither of us have yet been able to induce germination.

A final comment--I. lutea is reported to be more or less sparsely covered with spines, although specimens I have examined (University of California at Davis Herbarium) do not bear them. But if I. lutea is often spiny, it is the only carnivorous plant to be so.

Bertozzi, T. 1993. A.C.P.S. Bulletin 12:2, p. 9.
Cekic, C. 1993. A.C.P.S. Bulletin 12:2, p. 7.
Kane, P.M. 1993. A.C.P.S. Bulletin 12:1, p. 12.
Mameli, E. 1916. Ricerche anatomiche, fisiologiche e biologiche sulla Martynia lutea Lindl. Atti dell'Universita di Pavia, Serie 2, 16, p. 137-188.
Van Eseltine, G.P. 1929. A preliminary study of the unicorn plants (Martyniaceae): Technical Bulletin 149, (Geneva: New York State Agricultural Experiment Station), p. 1-41.
Heckard, L.R. 1993. In The Jepson Manual: Higher Plants of California, ed. Hickman, J.C., (Berkeley and Los Angeles: University of California Press), p. 762.
Morley, B.D., and Toelken, H.R., 1983. In Flowering plants in Australia, (Adelaide: Rigby), p. 275.

Postscript: In the time I wrote this, I have induced germination of Ibicella lutea, and obtained seed. Also, I learned that the spines are strictly located on the woody fruit.


10 November 2007