euphorbia mammillaris l or euphorbiaceae or cockscrew cactus plant

africa african cactus cactuses cape cob cockscrew corn dense desert dry endemic euphorbia euphorbiaceae fast flora foliage green growing horticultural horticulture indian mammillaris native photosynthesis plant plantation plants pointy province resilience resilient rib ribs shrublet single south species spine spines stem stems sturdy thick toothpicks tubercles weather