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1 Principal leaves either all simple (though sometimes palmately or pinnately lobed) or those that are basally disposed simple (those on the upper stem sometimes compound)
..2 Leaves 2-5× compound, with 5-200+ leaf divisions, at least some attached to secondary or higher-order inflorescence axes.
......4 Leaves 2-4× pinnately or pinnately-ternately compound, the ultimate segments consisting of relatively few (usually < 25), discreet, typically broad (elliptic, ovate, or lanceolate) leaflets.
......4 Leaves 2-5× pinnately or pinnately-ternately decompound, the ultimate segments either linear and < 1 mm wide (and then either flat or angled in ×-section) or broader than 1 mm wide, but if broader then many (> 25) and often imperfectly separated from one another.
........5 Leaves 2-5× pinnately or pinnately-ternately decompound, the ultimate segments linear and < 1 mm wide (and then either flat or angled in ×-section)
........5 Leaves 2-5× pinnately or pinnately-ternately decompound, the ultimate segments broader than 1 mm wide, but if broader then many (> 25) and often imperfectly separated from one another
..........6 Fruits (or ovaries when in flower) ornamented with hairs, bristles, barbs, or tubercles (clone)