Is anyone familiar with directional statistics? Circular or spherical?

I have a some data that I've never considered before - the distribution of bacteria through a plant, including crown and roots. I have presence/absence as well as abundance at numerous sample points throughout the plant. I further have distance and direction from the trunk for each sample point. It strikes me that these data fall within the realm of circular or spherical statistics, yet I have no experience in these areas. Any suggestions you can offer would be helpful.

In addition to the broader analysis question, I further have some specific issues I'm unsure how to deal with. I have multiple sample points at increasing distance along a single branch (or root) from the trunk. In many ways these sample points are not independent, but in some ways could be. Sample points on a branch that's completely filled with bacteria are likely not independent - the bacteria almost certainly spread from a single source. However, some branches may only have the bacteria at the tip...or in two tips. In this case, the remaining sample points may be independent. Should I consider these sample point not as independent samples, but instead as measures of the extent of infection? That is, each branch would be independent but the samples on each branch would be used to calculate a "distance" of infection? Does any of this make sense?

I'd really appreciate any help this community can offer.