Some plants that are likely to wound intruders are: dwarf conifers, such as bird's nest spruces; low growing shrubs, such as English yews and globose blue spruces (Picea pungens), also known as "Glauca Globosa"; or thorny plants that stay small, about three to four feet high and wide. One shrub that people aren't likely to hide behind, with its tight mass of thorny leaves, is Rotunda Chinese holly; hardy oranges (Poncirus trifoliata); and devil's walking stick (Aralia spinosa) are also good.