in general, carnivorous plants are poor competitors, because they invest too heavily in structures that have no selective advantage in nutrient-rich habitats. they succeed only where other plants fail. carnivores are to nutrients what cacti are to water. carnivory only pays off when the nutrient stress is high and where light is abundant. when these conditions are not met, some plants give up carnivory temporarily. "sarracenia" spp. produce flat, non-carnivorous leaves (phyllodes) in winter. light levels are lower than in summer, so light is more limiting than nutrients, and carnivory does not pay. the lack of insects in winter exacerbates the problem. damage to growing pitcher leaves prevent them from forming proper pitchers, and again, the plant produces a phyllode instead.