Serrate. With sharp teeth pointing forward.
Sessile. Without a stalk of any kind.
Simple. Of one piece; not compound.
Sinuate. Deeply or strongly undulate or wavy.
Sinus. A recess, cleft, or gap between two lobes.
Spatulate. Spatula-shaped.
Spike. An inflorescence consisting of a central rachis bearing a number of stalkless flowers.
Stamen. Pollen-bearing organ of the flower.
Staminate. Bearing stamens.
Stellate. Star-shaped.