cotyledon = one of two "seed leaves" used for food storage. The two cotyledons emerge above the soil, turn green, and photosynthize for a short period of time and then drop off the plant.

flower = the reproductive structure of soybean. It contains five petals, five sepals, 10 stamens, and 1 pistil. Soybean flowers are perfect and complete.

fully developed leaf = a leaf that has a leaf above it with unfolded leaflets. Soybean leaves are composed of the petiole and either 1 or 3 leaflets.

hypocotyl = a structure that connects root and stem regions of the soybean plant. During emergence, the hypocotyl elongates and pushes on the anchored root. Continued elongation brings the cotyledons to the soil surface. Varieties with purple flowers have purple hypocotyls, whereas hypocotyls of varieties with white flowers will turn green in sunlight.

leaflets = sub-part of leaf blade. All but the first node of soybean plants produce leaves with three leaflets.

main stem = the central stem of the soybean plant. Up to three branches can be produced on each main stem node.

node = place on stem where leaves, branches and racemes are attached. Plant height is related to the number of nodes and the length of the distance between each node (internode). Each node produces three buds.

petiole = part of the leaf that attaches the leaf to the stem. During normal maturity, petioles drop from the stem leaving a scar at the node.

pod = the developing ovary after fetilization. Soybean pods contain 1 to 4 seeds. After maturity the pod wall opens to allow for seed disperal.

raceme = the reproductive unit for soybean. This inflorescence contains no branches and flowers are attached to the central stalk with pedicels. Flower number can vary from 1 to more than 50.

seed = the fertilized ovule.

trifoliolate leaf = a leaf that contains three leaflets.

unfoliolate leaf = a leaf that contains only 1 leaflet. Soybeans produce two unifoliolate leaves and they are situated opposite each other on the first node.