McMillan, Paul. (1978). Some Thoughts And Observations on Sarracenia. Carnivorous Plant Newsletter. 7(4):105-107.
- In regard to Sarracenia evolution on the old peneplain surface in eastern North America, I think it should be kept in mind that there was really more topographic diversity then than [sic] is sometimes implied. Although the Appalachians probably exceeded Everest in height at the time of their origin during the Permian 200 million years ago judging by the enormous thickness of the erosion-produced sediments eventually produced, even at their period of maximum erosion some of them in the southeast reared over 2,000 feet above the predominating and nearly sea-level peneplain that surrounded them. There were subsequently two other major uplifts of the mountains that disrupted the old peneplains developed during the intervening erosional cycles. Mt. Davis in Penna. (part of the old original Appalchians which survives till this day) reared over a 1000 feet above the peneplains during the time of maximum erosion but toward the south (and the Gulf of Mexico) the elevations were much higher (2,000 feet) and so there was considerable topographic diversity with river valleys and intervening peaks. This would have provided enough isolation between inbreeding populations of Sarracenias to produce some of the present day species. I would hesitate to call all these populations Sarracenias. Very likely they were a now extinct (through evolutionary modification) and primitive precursor pitcherplant genus that ultimately differentiated into Sarracenia, Darlingtonia, and Heliamphora as they migrated to new regions.
Speirs, D.C. (1981). The evolution of carnivorous plants. Carnivorous Plant Newsletter, 10(3):62-65.
- It would be nice to have a time machine so as to see exactly how CP evolved. None being at hand, one must turn to the fossil record, but unfortunately it is very sparse on the subject. Droseraceae pollen first appeared in the Miocene period (26 to 7 million years ago), and Aldrovanda is reported from the Eocene (58 mya) of south England (Raven & Axelrod 1974). There is a report of Aldrovanda seeds having been found in interglacial deposits of Europe (Nikitin 1927) but these are quite recent. They are identical to modern seeds and this shed no light on the evolution of this genus. The aforementioned fossils indicate that CP are at least as old as the Eocene but not necessarily exactly that old, as earlier fossils may not have been preserved or not yet discovered.
- By considering present-day CP distribution together with continental drift, one can speculate when a particular CP family might have evolved. It seems likely, for example, that the Byblidaceae and Cephalotaceae, endemic to Australia, evolved after that continent was isolated from the others by drifting, after the late Eocene. In the Lentibulariaceae are the genera Pinguicula and Utricularia. The latter has a worldwide distribution. It is difficult to say whether this is because it evolved before the supercontinents split up or because aquatic plants can be dispersed more easily than terrestrials. Pinguicula is confined to the northern hemisphere, with a dip into South America. It seems probable that it evolved in Laurasia during the Tertiary, and spread to South America quite recently when Central America rose. The Sarraceniaceae are confined to North America and northern South America. Based on continental drift, they would have appeared after Laurasia broke up in the Tertiary, probably some time after the Eocene. By then North America was separated from Europe, isolated the ancestral stock and confining it to one continent. Dispersal to South America would have followed much later. The Droseraceae are worldwide as a whole, suggesting an origin in the Cretaceous or early Tertiary, before the continents had drifted very far from each other. Aldrovanda, being aquatic, may have travelled with greater ease than its fellow genera. It ranges from Europe to Africa, India, Japan, and northern Australia. Drosophyllum is confined to the Iberian peninsula, with apparently local dispersion to Morocco, unrelated to continental drift. Dionaea is, of course, endemic to southeastern North America. The difficulty here is to determine whether this endemism is a result of recent evolution or because the genus is arelict and formerly had a wider distribution. Drosera is worldwide, suggesting an early origin in the Cretaceous or Tertiary. Nepenthes is found from northern Australia to Sri Lanka and Madagascar. It may well have originated in Gondwanaland, as Australia, India, and Madagascar made up the northern coastline of that supercontinent. This suggests Nepenthes had a coastal distribution during the Cretaceous. Having written all this, I remind the reader that the foregoing is speculative and based on the assumption that CP distribution was determined mainly by continental drift. Long distance dispersal may have played a part in the matter. One wonders though, that if Drosera was spread about in such a manner, why then were Byblis and Cephalotus not so affected.