Opuntiaaciculata is separate from O.strigil, O. engelmannii, or O.lindheimeri, though it has been conflated with these species. A long-spined form was invalidly named O.strigilflexospina, but it is really just a minor spine variant of O.aciculata. Plants may reach 3 1/2-ft tall and spread to 6-ft across and form hemispherical mounds, but they are often smaller. The main branches/arms may ascend or may rest on edge with secondary branches rising from them. Often areoles are spineless or possess 1(2) small spines that slope down. Glochids are prominent and may be 1/2-inch long (or a bit more) and are arranged in a circle around the areoles. The prominent glochids can be as attractive as they are dangerous. The species has red, orange, magenta, or yellow flowers; yellow flowers are the most common. The plant is often encountered in southwestern gardens because of its attractive flowers and cladodes. Britton and Rose reported that the plant is found in scattered small colonies near Laredo, TX. See the originical citation. O.aciculata is tetraploid.