variegated horsetail: northern North America; Greenland; northern and central Europe
horsetail: perennial rushlike flowerless herbs with jointed hollow stems and narrow toothlike leaves that spread by creeping rhizomes; tend to become weedy; common in northern hemisphere; some in Africa and South America
deliberate defense: a defense organized before contact is made with the enemy and while time for organization is available; usually includes a fortified zone (with pillboxes) and communication systems