Question
What is the correct name for the first leaves (2 in this case) when a seed sprouts? My plant is Emex Spinosa a noxious invasive weed. The first leaves are very different from the next two leaves, then the plant proceeds to become prostrate with its several branches and thorny seed pods which have leaves like the second set of leaves.
It is a problem in Mission Bay- San Diego, Ca.

Answer
Greg,

The first two leaves, when a seed sprouts, are referred to as cotyledons. The first leaves that emerge are associated with the germination process and although they are leaves their primary role is supplying stored food until the first true leaves emerge and begin photosynthesis.
The cotyledons differ in form and function than the rest of the foliage on a new plant.

Scot