The evolutionary purpose of rubber , and the reason why it has appeared independently in plants as diverse as trees , guayule and dandelions , is that it gums up the mouthparts of herbivorous insects .

橡胶形成的进化目的，以及橡胶之所以分别出现在橡胶树、银胶菊、蒲公英等各种各样的植物中的原因，在于它能黏住食草昆虫的口器。