Definition of "sellery"

Take a quart of good boiling pease which put into a pot with a gallon of soft water whilst cold; add thereto a little beef or mutton, a little hung beef or bacon, and two or three large onions; boil all together while your soop is thick; salt it to your taste, and thicken it with a little wheat-flour; strain it thro' a cullender, boil a little sellery, cut it in small pieces, with a little crisp bread, and crisp a little spinage, as you would do parsley, then put it in a dish, and serve it up.

1764, Elizabeth Moxon, English Housewifery Exemplified‎

We had most of us fasted eight-and-forty hours, some more; it was time therefore to make enquiry among ourselves what store of sustenance had been brought from the wreck by dire providence of some, and what could be procured on the island by the industry of others; but the produce of the one amounted to no more than two or three pounds of biscuit-dust preserved in a bag; and all the success of those who ventured abroad, the weather being still exceedingly bad, was to kill one sea-gull and pick some wild sellery.

1816, Robert Kerr, A General History and Collection of Voyages and Travels, Volume 17‎