To prepare the artichokes, use kitchen shears or a sharp paring knife to snip the thorny tips off outer leaves of the artichoke (until you reach inner, purplish leaves). Rub the cut edges with lemon to prevent browning. Slice stem off so that artichoke will sit upright.
Combine breadcrumbs, Parmesan, garlic, scallions, parsley and dry seasonings in a large bowl. Add 1-1/4 cup olive oil and combine; this should have a consistency like stuffing.
Carefully separate leaves of the artichoke without breaking, stuffing as much filling down between and toward the base of each leaf as you can. Set artichokes upright in a stove-top safe pan and add water to 1-1/2 inch. Pour remaining oil slowly over artichokes, letting it seep in. Juice lemons over the top of the chokes, letting a bit of juice fall into the water to keep the artichokes green during steaming. Place a slice of lemon atop each artichoke.
Bring water to a boil, then reduce heat to low, cover the pan and steam the artichokes for 45 minutes to an hour, checking water level occasionally. Artichokes are done when a leaf pulls away fairly easily and the pith at the base of the leaf is soft.