Sheviis, Chapter 1, Mishnah 3. In the previous mishnah we learned that three trees in a beis se'ah which together produce enough for a cake of pressed figs - whether the measure is reckoned for each tree separately or for all three together, according to the various opinions that differ on this - permit plowing the entire field until Shavuos; and without them, the restriction of Pesach returns, which is the time plowing stops in a grain field.
The novel point of Mishnah 3:
Although the calculation is set according to a cake of pressed figs, which is a large round of figs, the matter is not limited to fig trees alone but applies to other kinds of trees as well. The mishnah discusses a barren tree that produces no fruit, and also a fruit tree of another species, and rules: "Ro'in osan" - we look at the tree and assess it as though it were a fruit tree producing figs.
Two situations following the assessment:
They meet the measure: If by this assessment they contain - again, whether each tree on its own or all three together - enough to make a cake of pressed figs, which is sixty maneh Italian, one may plow the entire beis se'ah on their account, including the area outside their immediate space.
They do not meet the measure: If they contain less than the measure, one plows until Shavuos only what the trees themselves require - the area surrounding the tree, which is the space needed for the one picking the figs and for his basket, as we mentioned earlier. But the rest of the field has the status of a grain field, and its plowing stops already at Pesach.
In summary: In this mishnah we learned that the standard of a cake of pressed figs is not unique to fig trees; rather, every tree - barren or a fruit tree of another species - is assessed by that standard as though it were producing figs. If they meet the measure, the entire beis se'ah is plowed on their account; if they do not meet the measure, only what the trees themselves require is plowed, and the rest of the field follows the law of a grain field from Pesach.