Pollination rigida", this allows the plant to self-pollinate, which is useful when biotic pollinators in the environment have decreased. It is possible for a plant have varying pollination methods, including both biotic and abiotic pollination. The orchid "Oeceoclades maculata" uses both rain and butterflies, depending on its environmental conditions. More commonly, pollination involves pollinators (also called pollen vectors): organisms that carry or move the pollen grains from the anther of one flower to the receptive part of the carpel or pistil (stigma) of another. Between 100,000 and 200,000 species of animal act as pollinators of the world's 250,000 species of flowering
Parthenium hysterophorus production, an additive in manure for biogas production, as a biopesticide, and as green manure and compost. Contact with the plant causes dermatitis and respiratory malfunction in humans, and dermatitis in cattle and domestic animals. The main substance responsible is parthenin, which is dangerously toxic. It also is responsible for bitter milk disease in livestock when their fodder is polluted with "Parthenium" leaves. Among other allelopathic effects of the species, the presence of "Parthenium" pollen grains inhibits fruit set in tomato, brinjal, beans, and a number of other crop plants. Light infestations of "Parthenium hysterophorus" in cultivated fields may be