My Stem’s Planted Firmly

My stem’s planted firmly where I am allotted.
My tail is wavy and my face is quite blotted.
I relay much emotion though flatly I’m spotted,
And I grow half my size whenever I’m dotted.
I can speak any language, yet utter no words.
I’m no seed, yet I am well known among birds.

But I do have a speech impediment:
I can say cage but not page, aged but not wage.
I can say deaf but not red, bed but not sled.

I live on a highway that’s structurally sound,
Where you might see my friends accidentally bound.
It has many lanes, and also long lines.
There are lots of sharp turns, but plenty of signs.

I am played but not won, made but not spun.
The key is to measure before you’ve begun.

What am I?