To see what filesystems are mounted, type mount by itself:

# mount
/dev/ide/host0/bus1/target0/lun0/part7 on / type xfs (rw,noatime,nodiratime)
proc on /proc type proc (rw)
none on /dev type devfs (rw)
tmpfs on /dev/shm type tmpfs (rw)
/dev/hdc6 on /mnt type ext2 (rw)

You can also view similar information by typing cat /proc/mounts. Since my Linux system uses devfs, the first line of my mount output lists a long path for the "root" partition block device. The "root" filesystem will get mounted automatically by the kernel at boot-time Systems that use the new devfs device-management filesystem for /dev have longer official names for the partition and disk block devices than Linux used to have in the past. For example, /dev/ide/host0/bus1/target0/lun0/part7 is the official name for /dev/hdc7, and /dev/hdc7 itself is just a symlink pointing to the official block device. You can determine if your system is using devfs by checking to see if the /dev/.devfsd file exists; if so, then devfs is active.