Sempervivum arachnoidum is a species of Sempervivum that has webbing. You can use this thread to post your pics of this family of plants. Note that the arachs have been heavily hybridized. Another interesting tidbit is that the arachs can be very small. Some of the smaller semps we have are arach hybrids.
Below is a pic of S. arach. 'Silver Crows' showing the dense webbing covering the growing crown of this plant.
