Plants do much more than sit there! Beyond our human use of plants as foods and medicines (human-plant interactions), they interact with each other (plant-plant interactions) as well as with pollinators, pathogens, and herbivores.  My work examines plant-plant interactions in the New England alpine zone, and human-plant interactions in southern Greenland and in the greenhouse. I studied interactions between the cushion plant, Diapensia lapponica, and the dwarf shrub, Vaccinium uliginosum, change along a gradient of physical severity in the White Mountains of New Hampshire. Much research demonstrates the benefits of cushion plants to other species, and even the detriment that may occur to the cushion as the success of its beneficiaries grows. My results show that both species respond to changes in the physical gradient, but surprisingly, the interaction between D. lapponica and V. uliginosum appears to be neutral; neither species exhibited physiological benefits or detriments in response to the presence of the other. Rather, plant architecture was a better predictor of whether the two species were found growing together. My work in Greenland investigated how Danish colonialism affected traditional knowledge and use of plants. My current work looks to exploit plants as biosensors for the Army. I will touch briefly on all three topics at GeoLunch.