BLACK PLASTIC:Sheet plastic that is placed around plants as a mulch to obstruct weeds, hold moisture, and absorb heat. Also called black polyethylene or black poly sheeting.
BLADE: A plant's leaf, such as a blade of grass; the expanded part of a leaf, petal, sepal, etc. as distinguished from the petiole or leafstalk.
BLANCH: To whiten or prevent from becoming green by excluding light. Blanching is applied to the stems or leaves of plants such as celery, lettuce, and endive. This is done by banking up the soil around the stems of the plants, tying the leaves together to keep the inner ones from light, or covering with pots, boxes, etc.
BLASTEMA: The point of growth from which any organs or part of an organ is developed.
BLEEDING: When sap or latex oozes from a plant or tree.
BLOOM: 1. The flower of a plant. 2. The state of blossoming. 3. A powdery, wax-like deposit or coating that covers certain fruits (such as apples, grapes and plums), vegetable leaves (such as cabbage), and succculent leaves.
BLOSSOM: 1. The flower of a plant, usually noticeable because of the colored leaflets that form it. 2. To put forth blossoms or flowers; to come into bloom.
BLOWBALL: The downy heads of seeds produced after the flowers have died. (i.e. dandelion, salsify, etc.)