<P> Being carnivorous allows the plant to grow better when the soil contains little nitrate or phosphate . In particular, an increased supply of nitrogen and phosphorus makes photosynthesis more efficient, because photosynthesis depends on the plant being able to synthesise very large amounts of the nitrogen - rich enzyme RuBisCO (ribulose - 1, 5 - bis - phosphate carboxylase / oxygenase), the most abundant protein on Earth . </P> <P> It is intuitively clear that the Venus flytrap is more carnivorous than Triphyophyllum peltatum . The former is a full - time moving snap - trap; the latter is a part - time, non-moving flypaper . The energy "wasted" by the plant in building and fuelling its trap is a suitable measure of the carnivory of the trap . </P> <P> Using this measure of investment in carnivory, a model can be proposed . Above is a graph of carbon dioxide uptake (potential for growth) against trap respiration (investment in carnivory) for a leaf in a sunny habitat containing no soil nutrients at all . Respiration is a straight line sloping down under the horizontal axis (respiration produces carbon dioxide). Gross photosynthesis is a curved line above the horizontal axis: as investment increases, so too does the photosynthesis of the trap, as the leaf receives a better supply of nitrogen and phosphorus . Eventually another factor (such as light intensity or carbon dioxide concentration) will become more limiting to photosynthesis than nitrogen or phosphorus supply . As a result, increasing the investment will not make the plant grow better . The net uptake of carbon dioxide, and therefore, the plant's potential for growth, must be positive for the plant to survive . There is a broad span of investment where this is the case, and there is also a non-zero optimum . Plants investing more or less than this optimum will take up less carbon dioxide than an optimal plant, and hence growing less well . These plants will be at a selective disadvantage . At zero investment the growth is zero, because a non-carnivorous plant cannot survive in a habitat with absolutely no soil - borne nutrients . Such habitats do not exist, so for example, Sphagnum absorbs the tiny amounts of nitrates and phosphates in rain very efficiently and also forms symbioses with diazotrophic cyanobacteria . </P> <P> In a habitat with abundant soil nutrients but little light (as shown above), the gross photosynthesis curve will be lower and flatter, because light will be more limiting than nutrients . A plant can grow at zero investment in carnivory; this is also the optimum investment for a plant, as any investment in traps reduces net photosynthesis (growth) to less than the net photosynthesis of a plant that obtains its nutrients from soil alone . </P>

How are carnivorous plants stronger than other plants