The first leaves that poke through the soil from the germinating seed are appropriately called "seed leaves". A biologist would call them "cotyledons", which is fun to say, but doesn't tell most folks much. These very first leaves are charged with providing "nourishment to the elementary plant". They often look sort of nondescript and, despite their initial vital role, soon take a back seat to the next players on the foliar front: the true leaves.
I like that image: true leaves. Leaves that are faithful; leaves that won't let you down. Leaves that are honest and will support the fruiting or flowering of just exactly what you planted. When the true leaves appear, that plant is pretty much on course, conforming to the original pattern, or to the essential characteristics of the genus. True leaves remain loyal, constant to the ideal character of the plant. True leaves are accurately fitted, placed or shaped. True leaves happen according to prediction or expectation.
True leaves don't lead us astray. They tell us when the plant is strong enough to withstand transplanting, and hopefully, we can stay true to the plants as we assist them on their journey toward fruition.
My photo of true leaves is (ironically) fuzzy but I hope you can see the difference between the seed leaves and the true leaves on these lettuce seedlings, that are about to be transplanted. The other photo shows the rows of transplanted seedlings that have just about filled the greenhouse at this stage of the Spring game.
(Cathy thanks Webster's New Universal Unabridged Dictionary for help in writing this Frog Log!)