Until the advent of molecular phylogeny, plant taxonomists had no clue where Cephalotus follicularis fits into the tree of life. The most common guesses were that it was related to Sarracenia and Nepenthes (as if they are related!) or to the Saxifragales where Drosera was once thought to reside as well.

Thanks to DNA sequencing we now know Cephalotus is in the order Oxalidales (oxalis) and not related to any other carnivorous plant. It ties in at the root of the Oxalidales and has as sisters 5 families with over 1900 species in 60 genera, most of which you have never heard of. The family Cephalotaceae has one genus with one species. For Cephalotus does a family tree like that fit the definition of orphan?

The DNA sequence data do not provide adequate resolution to show additional hierarchy. That means none of these families in the Oxalidales appear to be closer to Cephalotus than any other. The display order of the branches is arbitrary. I put them in this order because there are species in the Oxalidaceae, Connaraceae, and Cunoniaceae with a leaf structure similar to the apparent Cephalotus ancestral leaf structure. (Whether the family Huaceae should also be in the Oxalidales is debatable and not shown in the tree.)

The number of genera and species listed in the figure to some extent is a matter of opinion, but the numbers and geographic range give a good idea of the size and diversity of the families related to Cephalotus. Four of the six families are found in Southwest Australia where Cephalotus is found. The Elaeocarpaceae, Cunoniaceae, Brunelliaceae, and Connaraceae are generally evergreen shrubs. The Oxalidaceae consists mostly of herbaceous plants in the genus Oxalis but the family also contains some shrubs and small trees in other genera.

There are indications from fossils and models of molecular clocks that the split among the families of the Oxalidales occurred 80 to 100 million years ago when landscapes were dominated by gymnosperms and the angiosperms where just beginning to diversify. If the progenitors of all these families became distinct within a ten million year period 100 million years ago, there may be no way to sort out the relationships better than this. That is because there would be so few preserved DNA changes during that short period compared to the number of changes since then.

Within the order Oxalidales, the Oxalidaceae, Connaraceae, and Cunoniaceae have compound leaves. The species in the other families tend to have simple leaves. Leaf structure says more about the environment where the plants are found than their heritage. The same goes for flowers. Plant/pollinator interactions determine large scale aspects of flowers such as petals and colors. Cephalotus appears to have ancestral-like flowers and it may have the same pollinators it had 80 million years ago. Some of its relatives appear to also have ancestral-like flowers. That does not mean those relatives are the nearest relatives. It means those flower structures are adequate for reproduction.

There has been a long discussion in the literature about how the pitchers of Cephalotus are constructed. Plant anatomists have been staring at and slicing and dicing the pitchers since the middle of the 19th century. On a general inspection the pitchers are as elaborate as any Nepenthes pitcher. But more detailed inspection showed that the pitchers are not your folded simple leaf like with Sarracenia and Nepenthes. Lloyd (1942) and DeGreef (1990 PDF) summarize the studies demonstrating this and discuss the results under the assumption Cephalotus is a member of the Saxifragales and proto-Cephalotus had a peltate saxifrage-type leaf.

Evidence that Cephalotus is derived from a peltate leaf is the arrangement of vascular bundles in the petiole. In a typical simple or flat leaf the bundles are arranged in an arc. In Cephalotus they are arranged in a circle exactly like Oxalis leaves except Oxalis has one fewer bundle. Curiously you can also take an Oxalis leaf and easily fold it into a pitcher. To make a Cephalotus pitcher requires some stretching. The lid would be one leaflet. (there is evidence it evolved from two leaflets). The other leaflets would be stretched around to become a pitcher. The leaf ridges that act as prey guides could be at the sutures between the pitcher leaflets or more likely the midveins of the leaflets.

For more information on Cephalotus leaves, please see Brittnacher (2020) (PDF). The study showed, using aberrant leaves, that it appears that the Cephaltous pitcher could have evolved from a compound, peltate or near peltate leaf, with five leaflets. There are species in the Cunoniaceae that have such leaves. That does not mean that Cephalotus is most closely to the Cunoniaceae. Cephalotus has charateristics found in a number of families in the Oxalidales. At the time each of the current families diverged, they would have been classified as separate species in the same genus and had much in common. Eighty million years is plenty of time for the progenitors of Cephalotus to develop their own peltate leaf style and then have that evolve into a pitcher.

Probably the biggest impediment for some people to understand Cephalotus pitchers is the simple, non-carnivorous leaves the plant produces seasonally. They are essentially expanded petioles and extremely unlikely to be representative of ancestral leaves. The simple leaves are produced during the winter when presumably there are not enough prey available to make production of pitchers advantageous. They also tend to be more common on shade grown plants. The occasional aberrant leaves we see more than likely happen when the development pathway to produce pitchers kicks in after the leaf has started to grow and it is too late for that leaf to make proper pitchers. The structure of the aberrant leaves is totally consistent with the peltate nature of the trapping leaves and an ancestor with Oxalis-like leaves.

-- John Brittnacher 
March 2011
Latest update February 2026

For a more detailed discussion please see the following articles and articles they reference.

Keep in mind each author states their view at a given time with the data they have at that time. Recent discoveries could modify their ideas.

Brittnacher, John (2020) Evolution of the Cephalotus pitcher. Carniv. Pl. Newslett. 49(3):103-120. https://doi.org/10.55360/cpn493.jb736 (PDF)

Cross, Adam, Nick Kalfas, Richard Nunn and John Conran (2019) Cephalotus - the Albany Pitcher Plant. Redfern Natural History Productions, Poole, Dorset, England.

DeGreef, John D. (1990) Cephalotus follicularis: history and evolution. Carniv. Pl. Newslett. 19(3-4):95-103 ( PDF )

Lloyd, Francis E. (1942) The Carnivorous Plants. Chronica Botanica, Waltham MA, USA. (reprinted by Lloyd Press).

Mann, Phill (2005) Observations on Cephalotus follicularis and Drosera binata in Western Australia. Carniv. Pl. Newslett. 34(3):68-70 ( PDF )

Richard Nunn (2014) New insights into the growth cycle of Cephalotus follicularis. Carniv. Pl. Newslett. 43(3):93-96 (PDF)

Stevens, P. F. (2001 onwards). Oxalidales. IN: Angiosperm Phylogeny Website. Version 14, July 2017 [and more or less continuously updated since].

Cephalotus follicularis in cultivation.

Longitudinal section through a Cephalotus trap.

Oxalis leaf, an example of a compound peltate leaf consisting of three leaflets. Photo by Tom Cahill.

Cephalotus sprout showing a unifacial phylodia as the first true leaf and a pitcher as the second true leaf. This aspect may be variable. One of the cotyledons has the remains of the seed attached.

Cephalotus juvenile leaf showing fully windowed lid and sparse "teeth".

Aberrant winter foliage leaf.

Aberrant winter foliage leaf.

Aberrant winter foliage leaf with labeled sections of the leaf that develop into pitcher components in normal leaves. Image from Brittnacher (2020).

Aberrant Cephalotus leaf showing how the lid is comprised of two parts. Photo by RL7836.

Another example of the bipartite pitcher lid on an aberrant winter foliage leaf. Notice the typical pitcher lid windows. A flat aberant leaf is in the background. Photo © Robert Gibson.