Ramalina Farinacea, Sorediate Margins

Day 76: Lichen terminology can be very confusing even for botanists because certain structures have no counterpart in the physiology of vascular plants. My readers will have heard me use the term "soredia/soredium" for a specific type of vegetative propagule generated by some lichens, and they may also recall having read the word "soralia." Soralia are where soredia are produced. They manifest as small patches where the lichen cortex ("skin") has cracked or broken down. The emerging soredia often have a granular appearance and lack any cortex; soredia are one of the parent lichen's means of reproducing. In the inset, you can see the soralia/soredia along the margins of this fine specimen of Ramalina farinacea from Ohop Valley. Many lichens have more than one reproductive strategy to ensure their survival as species. Some are capable of reproducing both sexually and asexually. On the whole, lichens are atonishingly successful in the natural scheme. They were here long before humankind, and unless we pollute them out of existence, they will endure long after evidence of our brief passage has faded from the surface of the Earth.