If your goal is to transfer all files from
* wildcard does the trick:
$ scp ~/local_dir/* email@example.com:/var/www/html/target_dir
-r option means "recursively", so you must write it when you're trying to transfer an entire directory or several directories.
Recursively copy entire directories. Note that scp follows symbolic links encountered in the tree traversal.
So if you have sub-directories inside
local_dir, the last example will only transfer files, but if you set the
-r option, it will transfer files and directories.