Joshua trees (Yucca brevifolia) dominate much of the Black Rock area with their bright green leaves and spindly forms. These plants absorb as much water as possible after summer rains or winter snows through shallow roots that extend in a wide subterranean circle from their trunks. This leads to the fairly regular spacing of individual plants. Two Joshua trees growing near one another are likely the same individual, connected underground through networks of thin roots. Joshua trees store water in their trunks and branches, making them quite heavy during wet years and prone to tipping over or dropping branches. Take care not to climb on or attach ropes or hammocks to Joshua trees, despite their solid appearances they can be easily toppled.