At all events, the plants outside are on the whole quite different from the hay-field.
Of course: that is what makes the field look green and the moor brown.
Not a doubt.

They are so different, that they look like bits of two different continents.

Scrambling over the fence is like scrambling out of Europe into Australia.

Now, how was that difference made?
Think.
Don't guess, but think.

Why does the rich grass come up to the bank, and yet not spread beyond it?
I suppose because it cannot get over.
Not get over?
Would not the wind blow the seeds, and the birds carry them?
They do get over, in millions, I don't doubt, every summer.
Then why do they not grow?
Think.
Is there any difference in the soil inside and out?
A very good guess.