Nepenthes are truly an old species. First it exhibits a prehistoric pollination method of being dioecious (separate sexes on separate plants), examples of dioecious flowering occurs in other prehistoric old plants (i.e. cycads).
These plants had to evolve to insectivorousness due to lack of nutrients in their heath-bogs and rocky outcroppings. A significant supply in water was the determining factor in allowing diversity to happen. Even to this day, nepenthes can only occupy areas where rainfall is high. These plants lack any succulence or thickened stems or tissues that allow these plants to sit through droughts. Thus steady and reliable rainfall was not a factor in developing these plants. So since water was not scarce or difficult to obtain, these plants had to adapt to other strategies related to the environment. Since many nepenthes occupy areas where soil nutrients were poor or the soil had high concentrations of serpentine or ultramific layers, this prevented other plant species which are more faster and evasive from getting established. It is my belief that many nepenthes species rely on the shelter of a more aggressive species to get a start next to. These competitors started out with ample supply of nutrients and moisture, but eventually their roots ran into a higher PH soil or soils where calcium, magnesium and lime was high, thus stunting its growth and preventing an otherwise evasive species to outshadow the weaker and slow growing nepenthes. Nepenthes which have the ability to trap its own food for nitrogen and other trace minerals, soon could get a faster foothold on their environment and soil nutrient and combined with an endless supply of water and sunlight, now can overtake the small stunted tree or sapling.
What I also believe is that many nepenthes are high pH requirement growers and many people do not realize that they need this in order to develop properly. I believe that many nepenthes grow acidically in the seedling age and until their root system digs deeper into the substrate, they will soon require a higher pH soil. It is simple to understand that nepenthes grows acidly. Most upper layers over a bedrock of coral (as with most of the pacific islands) have a shallow decomposed region of plant material making a thin layer of acid or composted material. Once the plant penetrates this layer, then and only then do they exhibit some of their true characteristics.
I have a plant labeled northiana x (spectabilis x veitchii) and since I read somewhere that northiana grow in a very basic soil, I repotted it into a deeper pot with the bottom third composed of pure coral chips. I added layers of coco bark and fir bark and even coarse peat moss and hapu'u (fern fiber) to this mixture.
I later learned that this wasn't a northiana cross, but a bicalcarata cross and by then the plant had developed into a very heavy growing species with leathery leaves and robust pitchers. I have another clone of this same cross growing in a different area in lmost pure peat and coco bark mix. It is softer and more bigger leafed than the plant in this media.
Oh well, I seem to be going off track. I will perhaps start another section with regards to this topic. Sorry for boring everyone.
More later,
M