text: Caltha palustris is infertile when self-pollinated. Rather high fertility in crosses between sibling plants suggest that this phenomenon is genetically regulated by several genes. This regulation mechanism also occurs in Ranunculus and as far as known only in these two genera.
  Seed dispersal
  In Caltha palustris up to two hundred seeds may be produced by each flower. When the follicles open, they form a "splash cup". When a raindrop hits one at the right angle, the walls are shaped such that the seeds are expelled. The seeds also have some spongy tissue that makes them float on water, until they wash up in a location that may be suitable for this species to grow.
  Diseases
  The marsh-marigold is affected by the rust species Puccinia calthea and P. calthicola.
  Toxicity
  Caltha contains several active substances of which the most important from a toxicological point of view is protoanemonin. Larger quantities of the plant may cause convulsions, burning of the throat, vomiting, bloody diarrhea, dizziness and fainting. Contact of the skin or mucous membranes with the juices can cause blistering or inflammation, and gastric illness if ingested. Younger parts seem to contain less toxics and heating breaks these substances down. Small amounts of Caltha in hay do not cause problems when fed to husbandry, but larger quantities lead to gastric illness.
  Additionally, plants that live in raw water may carry toxic organisms which can be neutralized by cooking.