the sundew genus ("drosera") consists of over 100 species of active flypapers whose mucilage glands are borne at the end of long tentacles, which frequently grow fast enough in response to prey (thigmotropism) to aid the trapping process. the tentacles of "d. burmanii" can bend 180° in a minute or so. sundews are extremely cosmopolitan and are found on all the continents except the antarctic mainland. they are most diverse in australia, the home to the large subgroup of pygmy sundews such as "d. pygmaea" and to a number of tuberous sundews such as "d. peltata", which form tubers that aestivate during the dry summer months. these species are so dependent on insect sources of nitrogen that they generally lack the enzyme nitrate reductase, which most plants require to assimilate soil-borne nitrate into organic forms.