Katie started in the direction of the woman's voice. She stumbled over fallen, slick wood and brambles she couldn't see. Whatever magic that had cleared a path for her was gone. She struggled through the jungle before calling out, "Can you hear me? I can't see much. You'll have to say something, so I can find you."
The occurrence of hybrids in nature explains the difficulty experienced by botanists in deciding on what is a species, and the widely different limitations of the term adopted by different observers in the case of willows, roses, brambles, &c. The artificial process is practically the same in hybridization as in cross-fertilization, but usually requires more care.